Aaron Lindenberg

All Publications

• Electrochemical Control of the Ultrafast Lattice Response of a Layered Semimetal. Advanced science (Weinheim, Baden-Wurttemberg, Germany) de Quesada, F. A., Muscher, P. K., Krakovsky, E. S., Sood, A., Poletayev, A. D., Sie, E. J., Nyby, C. M., Irvine, S. J., Zajac, M. E., Luo, D., Shen, X., Hoffmann, M. C., Kramer, P. L., England, R. J., Reid, A. H., Weathersby, S. P., Dresselhaus-Marais, L. E., Rehn, D. A., Chueh, W. C., Lindenberg, A. M. 2024: e2411344

  Abstract

  The unique layer-stacking in two-dimensional (2D) van der Waals materials facilitates the formation of nearly degenerate phases of matter and opens novel routes for the design of low-power, reconfigurable functional materials. Electrochemical ion intercalation between stacked layers offers a promising approach to stabilize bulk metastable phases and to explore the effects of extreme carrier doping and strain. However, in situ characterization methods to study the structural evolution and dynamical functional properties of these intercalated materials remains limited. Here a novel experimental platform is presented capable of simultaneously performing electrochemical lithium-ion intercalation and multimodal ultrafast characterization of the lattice using both electron diffraction and nonlinear optical techniques. Using the layered semimetal WTe2 as a model system, the interlayer shear phonon mode that modulates stacking between 2Dlayers is probed, showing that small amounts of lithiation enhance the amplitude and lifetime of the phonon, contrary to expectations. This results from the dynamically fluctuating and anharmonic structure between nearly degenerate phases at room temperature, which can be stabilized by electronic carriers accompanying the inserted lithium ions. At high lithiation, the Td' structure emerges and quenches the phonon response. This work defines new approaches for using electrochemistry to engineer the dynamic structure of 2D materials.

  View details for DOI 10.1002/advs.202411344

  View details for PubMedID 39686650

• 3D Heisenberg universality in the van der Waals antiferromagnet NiPS₃ NPJ QUANTUM MATERIALS Plumley, R., Mardanya, S., Peng, C., Nokelainen, J., Assefa, T., Shen, L., Burdet, N., Porter, Z., Petsch, A., Israelski, A., Chen, H., Lee, J., Morley, S., Roy, S., Fabbris, G., Blackburn, E., Feiguin, A., Bansil, A., Lee, W., Lindenberg, A. M., Chowdhury, S., Dunne, M., Turner, J. J. 2024; 9 (1)

  View details for DOI 10.1038/s41535-024-00696-6

  View details for Web of Science ID 001366178200001

• Ultrafast Symmetry Control in Photoexcited Quantum Dots. Advanced materials (Deerfield Beach, Fla.) Guzelturk, B., Portner, J., Ondry, J., Ghanbarzadeh, S., Tarantola, M., Jeong, A., Field, T., Chandler, A. M., Wieman, E., Hopper, T. R., Watkins, N. E., Yu, J., Cheng, X., Lin, M. F., Luo, D., Kramer, P. L., Shen, X., Reid, A. H., Borkiewicz, O., Ruett, U., Zhang, X., Lindenberg, A. M., Ma, J., Schaller, R. D., Talapin, D. V., Cotts, B. L. 2024: e2414196

  Abstract

  Symmetry control is essential for realizing unconventional properties, such as ferroelectricity, nonlinear optical responses, and complex topological order, thus it holds promise for the design of emerging quantum and photonic systems. Nevertheless, fast and reversible control of symmetry in materials remains a challenge, especially for nanoscale systems. Here, reversible symmetry changes are unveiled in colloidal lead chalcogenide quantum dots on picosecond timescales. Using a combination of ultrafast electron diffraction and total X-ray scattering, in conjunction with atomic-scale structural modeling and first-principles calculations, it is revealed that symmetry-broken lead sulfide quantum dots restore to a centrosymmetric phase upon photoexcitation. The symmetry restoration is driven by photoexcited electronic carriers, which suppress lead off-centering for about 100 ps. Furthermore, the change in symmetry is closely correlated with the electronic properties, and the bandgap transiently red-shifts in the symmetry-restored quantum dots. Overall, this study elucidates reversible symmetry changes in colloidal quantum dots, and more broadly defines a new methodology to optically control symmetry in nanoscale systems on ultrafast timescales.

  View details for DOI 10.1002/adma.202414196

  View details for PubMedID 39584653

• Colossal Strain Tuning of Ferroelectric Transitions in KNbO3 Thin Films. Advanced materials (Deerfield Beach, Fla.) Hazra, S., Schwaigert, T., Ross, A., Lu, H., Saha, U., Trinquet, V., Akkopru-Akgun, B., Gregory, B. Z., Mangu, A., Sarker, S., Kuznetsova, T., Sarker, S., Li, X., Barone, M. R., Xu, X., Freeland, J. W., Engel-Herbert, R., Lindenberg, A. M., Singer, A., Trolier-McKinstry, S., Muller, D. A., Rignanese, G. M., Salmani-Rezaie, S., Stoica, V. A., Gruverman, A., Chen, L. Q., Schlom, D. G., Gopalan, V. 2024: e2408664

  Abstract

  Strong coupling between polarization (P) and strain (ɛ) in ferroelectric complex oxides offers unique opportunities to dramatically tune their properties. Here colossal strain tuning of ferroelectricity in epitaxial KNbO3 thin films grown by sub-oxide molecular beam epitaxy is demonstrated. While bulk KNbO3 exhibits three ferroelectric transitions and a Curie temperature (Tc) of ≈676 K, phase-field modeling predicts that a biaxial strain of as little as -0.6% pushes its Tc > 975 K, its decomposition temperature in air, and for -1.4% strain, to Tc > 1325 K, its melting point. Furthermore, a strain of -1.5% can stabilize a single phase throughout the entire temperature range of its stability. A combination of temperature-dependent second harmonic generation measurements, synchrotron-based X-ray reciprocal space mapping, ferroelectric measurements, and transmission electron microscopy reveal a single tetragonal phase from 10 K to 975 K, an enhancement of ≈46% in the tetragonal phase remanent polarization (Pr), and a ≈200% enhancement in its optical second harmonic generation coefficients over bulk values. These properties in a lead-free system, but with properties comparable or superior to lead-based systems, make it an attractive candidate for applications ranging from high-temperature ferroelectric memory to cryogenic temperature quantum computing.

  View details for DOI 10.1002/adma.202408664

  View details for PubMedID 39533481

• Coupling to octahedral tilts in halide perovskite nanocrystals induces phonon-mediated attractive interactions between excitons. Nature physics Yazdani, N., Bodnarchuk, M. I., Bertolotti, F., Masciocchi, N., Fureraj, I., Guzelturk, B., Cotts, B. L., Zajac, M., Rainò, G., Jansen, M., Boehme, S. C., Yarema, M., Lin, M. F., Kozina, M., Reid, A., Shen, X., Weathersby, S., Wang, X., Vauthey, E., Guagliardi, A., Kovalenko, M. V., Wood, V., Lindenberg, A. M. 2024; 20 (1): 47-53

  Abstract

  Understanding the origin of electron-phonon coupling in lead halide perovskites is key to interpreting and leveraging their optical and electronic properties. Here we show that photoexcitation drives a reduction of the lead-halide-lead bond angles, a result of deformation potential coupling to low-energy optical phonons. We accomplish this by performing femtosecond-resolved, optical-pump-electron-diffraction-probe measurements to quantify the lattice reorganization occurring as a result of photoexcitation in nanocrystals of FAPbBr3. Our results indicate a stronger coupling in FAPbBr3 than CsPbBr3. We attribute the enhanced coupling in FAPbBr3 to its disordered crystal structure, which persists down to cryogenic temperatures. We find the reorganizations induced by each exciton in a multi-excitonic state constructively interfere, giving rise to a coupling strength that scales quadratically with the exciton number. This superlinear scaling induces phonon-mediated attractive interactions between excitations in lead halide perovskites.

  View details for DOI 10.1038/s41567-023-02253-7

  View details for PubMedID 38261834

  View details for PubMedCentralID PMC10791581

• Non-equilibrium pathways to emergent polar supertextures. Nature materials Stoica, V. A., Yang, T., Das, S., Cao, Y., Wang, H. H., Kubota, Y., Dai, C., Padma, H., Sato, Y., Mangu, A., Nguyen, Q. L., Zhang, Z., Talreja, D., Zajac, M. E., Walko, D. A., DiChiara, A. D., Owada, S., Miyanishi, K., Tamasaku, K., Sato, T., Glownia, J. M., Esposito, V., Nelson, S., Hoffmann, M. C., Schaller, R. D., Lindenberg, A. M., Martin, L. W., Ramesh, R., Matsuda, I., Zhu, D., Chen, L. Q., Wen, H., Gopalan, V., Freeland, J. W. 2024

  Abstract

  Ultrafast stimuli can stabilize metastable states of matter inaccessible by equilibrium means. Establishing the spatiotemporal link between ultrafast excitation and metastability is crucial to understand these phenomena. Here we utilize single-shot optical pump-X-ray probe measurements to capture snapshots of the emergence of a persistent polar vortex supercrystal in a heterostructure that hosts a fine balance between built-in electrostatic and elastic frustrations by design. By perturbing this balance with photoinduced charges, an initially heterogeneous mixture of polar phase disorders within a few picoseconds, leading to a state composed of disordered ferroelectric and suppressed vortex orders. On the picosecond-nanosecond timescales, transient labyrinthine fluctuations develop, accompanied by the recovery of the vortex order. On longer timescales, these fluctuations are progressively quenched by dynamical strain modulations, which drive the collective emergence of a single vortex supercrystal phase. Our results, corroborated by dynamical phase-field modelling, reveal non-equilibrium pathways following the ultrafast excitation of designer systems to persistent metastability.

  View details for DOI 10.1038/s41563-024-01981-2

  View details for PubMedID 39317816

  View details for PubMedCentralID 8024274

• Roadmap on low-power electronics APL MATERIALS Ramesh, R., Salahuddin, S., Datta, S., Diaz, C. H., Nikonov, D. E., Young, I. A., Ham, D., Chang, M., Khwa, W., Lele, A., Binek, C., Huang, Y., Sun, Y., Chu, Y., Prasad, B., Hoffmann, M., Hu, J., Yao, Z., Bellaiche, L., Wu, P., Cai, J., Appenzeller, J., Datta, S., Camsari, K. Y., Kwon, J., Incorvia, J. C., Asselberghs, I., Ciubotaru, F., Couet, S., Adelmann, C., Zheng, Y., Lindenberg, A. M., Evans, P. G., Ercius, P., Radu, I. P. 2024; 12 (9)

  View details for DOI 10.1063/5.0184774

  View details for Web of Science ID 001314610400001

• Giant Terahertz Birefringence in an Ultrathin Anisotropic Semimetal. Nano letters Sie, E. J., Othman, M. A., Nyby, C. M., Pemmaraju, D., Garcia, C. A., Wang, Y., Guzelturk, B., Xia, C., Xiao, J., Poletayev, A., Ofori-Okai, B. K., Hoffmann, M. C., Park, S., Shen, X., Yang, J., Li, R., Reid, A. H., Weathersby, S., Muscher, P., Finney, N., Rhodes, D., Balicas, L., Nanni, E., Hone, J., Chueh, W., Devereaux, T. P., Narang, P., Heinz, T. F., Wang, X., Lindenberg, A. M. 2024

  Abstract

  Manipulating the polarization of light at the nanoscale is key to the development of next-generation optoelectronic devices. This is typically done via waveplates using optically anisotropic crystals, with thicknesses on the order of the wavelength. Here, using a novel ultrafast electron-beam-based technique sensitive to transient near fields at THz frequencies, we observe a giant anisotropy in the linear optical response in the semimetal WTe2 and demonstrate that one can tune the THz polarization using a 50 nm thick film, acting as a broadband wave plate with thickness 3 orders of magnitude smaller than the wavelength. The observed circular deflections of the electron beam are consistent with simulations tracking the trajectory of the electron beam in the near field of the THz pulse. This finding offers a promising approach to enable atomically thin THz polarization control using anisotropic semimetals and defines new approaches for characterizing THz near-field optical response at far-subwavelength length scales.

  View details for DOI 10.1021/acs.nanolett.4c00758

  View details for PubMedID 38717626

• Solution-phase sample-averaged single-particle spectroscopy of quantum emitters with femtosecond resolution. Nature materials Shi, J., Shen, Y., Pan, F., Sun, W., Mangu, A., Shi, C., McKeown-Green, A., Moradifar, P., Bawendi, M. G., Moerner, W. E., Dionne, J. A., Liu, F., Lindenberg, A. M. 2024

  Abstract

  The development of many quantum optical technologies depends on the availability of single quantum emitters with near-perfect coherence. Systematic improvement is limited by a lack of understanding of the microscopic energy flow at the single-emitter level and ultrafast timescales. Here we utilize a combination of fluorescence correlation spectroscopy and ultrafast spectroscopy to capture the sample-averaged dynamics of defects with single-particle sensitivity. We employ this approach to study heterogeneous emitters in two-dimensional hexagonal boron nitride. From milliseconds to nanoseconds, the translational, shelving, rotational and antibunching features are disentangled in time, which quantifies the normalized two-photon emission quantum yield. Leveraging the femtosecond resolution of this technique, we visualize electron-phonon coupling and discover the acceleration of polaronic formation on multi-electron excitation. Corroborated with theory, this translates to the photon fidelity characterization of cascaded emission efficiency and decoherence time. Our work provides a framework for ultrafast spectroscopy in heterogeneous emitters, opening new avenues of extreme-scale characterization for quantum applications.

  View details for DOI 10.1038/s41563-024-01855-7

  View details for PubMedID 38589542

  View details for PubMedCentralID 5615041

• Publisher Correction: The persistence of memory in ionic conduction probed by nonlinear optics. Nature Poletayev, A. D., Hoffmann, M. C., Dawson, J. A., Teitelbaum, S. W., Trigo, M., Islam, M. S., Lindenberg, A. M. 2024

  View details for DOI 10.1038/s41586-024-07124-6

  View details for PubMedID 38291189

• Hidden phonon highways promote photoinduced interlayer energy transfer in twisted transition metal dichalcogenide heterostructures. Science advances Johnson, A. C., Georgaras, J. D., Shen, X., Yao, H., Saunders, A. P., Zeng, H. J., Kim, H., Sood, A., Heinz, T. F., Lindenberg, A. M., Luo, D., da Jornada, F. H., Liu, F. 2024; 10 (4): eadj8819

  Abstract

  Vertically stacked van der Waals (vdW) heterostructures exhibit unique electronic, optical, and thermal properties that can be manipulated by twist-angle engineering. However, the weak phononic coupling at a bilayer interface imposes a fundamental thermal bottleneck for future two-dimensional devices. Using ultrafast electron diffraction, we directly investigated photoinduced nonequilibrium phonon dynamics in MoS2/WS2 at 4° twist angle and WSe2/MoSe2 heterobilayers with twist angles of 7°, 16°, and 25°. We identified an interlayer heat transfer channel with a characteristic timescale of ~20 picoseconds, about one order of magnitude faster than molecular dynamics simulations assuming initial intralayer thermalization. Atomistic calculations involving phonon-phonon scattering suggest that this process originates from the nonthermal phonon population following the initial interlayer charge transfer and scattering. Our findings present an avenue for thermal management in vdW heterostructures by tailoring nonequilibrium phonon populations.

  View details for DOI 10.1126/sciadv.adj8819

  View details for PubMedID 38266081

• The persistence of memory in ionic conduction probed by nonlinear optics. Nature Poletayev, A. D., Hoffmann, M. C., Dawson, J. A., Teitelbaum, S. W., Trigo, M., Islam, M. S., Lindenberg, A. M. 2024; 625 (7996): 691-696

  Abstract

  Predicting practical rates of transport in condensed phases enables the rational design of materials, devices and processes. This is especially critical to developing low-carbon energy technologies such as rechargeable batteries1-3. For ionic conduction, the collective mechanisms4,5, variation of conductivity with timescales6-8 and confinement9,10, and ambiguity in the phononic origin of translation11,12, call for a direct probe of the fundamental steps of ionic diffusion: ion hops. However, such hops are rare-event large-amplitude translations, and are challenging to excite and detect. Here we use single-cycle terahertz pumps to impulsively trigger ionic hopping in battery solid electrolytes. This is visualized by an induced transient birefringence, enabling direct probing of anisotropy in ionic hopping on the picosecond timescale. The relaxation of the transient signal measures the decay of orientational memory, and the production of entropy in diffusion. We extend experimental results using in silico transient birefringence to identify vibrational attempt frequencies for ion hopping. Using nonlinear optical methods, we probe ion transport at its fastest limit, distinguish correlated conduction mechanisms from a true random walk at the atomic scale, and demonstrate the connection between activated transport and the thermodynamics of information.

  View details for DOI 10.1038/s41586-023-06827-6

  View details for PubMedID 38267678

  View details for PubMedCentralID 5482052

• Terahertz Radiation of Plasmonic Hot Carriers Taghinejad, M., Xia, C., Hrton, M., Lee, K., Kim, A. S., Li, Q., Guzelturk, B., Kalousek, R., Xu, F., Cai, W., Lindenberg, A. M., Brongersma, M. L., Lin, S. Y., Adibi, A., Scherer, A. SPIE-INT SOC OPTICAL ENGINEERING. 2024

  View details for DOI 10.1117/12.3010182

  View details for Web of Science ID 001209319500001

• Accelerating Quantum Materials Development with Advances in Transmission Electron Microscopy. Chemical reviews Moradifar, P., Liu, Y., Shi, J., Siukola Thurston, M. L., Utzat, H., van Driel, T. B., Lindenberg, A. M., Dionne, J. A. 2023

  Abstract

  Quantum materials are driving a technology revolution in sensing, communication, and computing, while simultaneously testing many core theories of the past century. Materials such as topological insulators, complex oxides, superconductors, quantum dots, color center-hosting semiconductors, and other types of strongly correlated materials can exhibit exotic properties such as edge conductivity, multiferroicity, magnetoresistance, superconductivity, single photon emission, and optical-spin locking. These emergent properties arise and depend strongly on the material's detailed atomic-scale structure, including atomic defects, dopants, and lattice stacking. In this review, we describe how progress in the field of electron microscopy (EM), including in situ and in operando EM, can accelerate advances in quantum materials and quantum excitations. We begin by describing fundamental EM principles and operation modes. We then discuss various EM methods such as (i) EM spectroscopies, including electron energy loss spectroscopy (EELS), cathodoluminescence (CL), and electron energy gain spectroscopy (EEGS); (ii) four-dimensional scanning transmission electron microscopy (4D-STEM); (iii) dynamic and ultrafast EM (UEM); (iv) complementary ultrafast spectroscopies (UED, XFEL); and (v) atomic electron tomography (AET). We describe how these methods could inform structure-function relations in quantum materials down to the picometer scale and femtosecond time resolution, and how they enable precision positioning of atomic defects and high-resolution manipulation of quantum materials. For each method, we also describe existing limitations to solve open quantum mechanical questions, and how they might be addressed to accelerate progress. Among numerous notable results, our review highlights how EM is enabling identification of the 3D structure of quantum defects; measuring reversible and metastable dynamics of quantum excitations; mapping exciton states and single photon emission; measuring nanoscale thermal transport and coupled excitation dynamics; and measuring the internal electric field and charge density distribution of quantum heterointerfaces- all at the quantum materials' intrinsic atomic and near atomic-length scale. We conclude by describing open challenges for the future, including achieving stable sample holders for ultralow temperature (below 10K) atomic-scale spatial resolution, stable spectrometers that enable meV energy resolution, and high-resolution, dynamic mapping of magnetic and spin fields. With atomic manipulation and ultrafast characterization enabled by EM, quantum materials will be poised to integrate into many of the sustainable and energy-efficient technologies needed for the 21st century.

  View details for DOI 10.1021/acs.chemrev.2c00917

  View details for PubMedID 37979189

• Coupling to octahedral tilts in halide perovskite nanocrystals induces phonon-mediated attractive interactions between excitons NATURE PHYSICS Yazdani, N., Bodnarchuk, M. I., Bertolotti, F., Masciocchi, N., Fureraj, I., Guzelturk, B., Cotts, B. L., Zajac, M., Raino, G., Jansen, M., Boehme, S. C., Yarema, M., Lin, M., Kozina, M., Reid, A., Shen, X., Weathersby, S., Wang, X., Vauthey, E., Guagliardi, A., Kovalenko, M. V., Wood, V., Lindenberg, A. M. 2023

  View details for DOI 10.1038/s41567-023-02253-7

  View details for Web of Science ID 001103093700003

• Determining hot-carrier transport dynamics from terahertz emission. Science (New York, N.Y.) Taghinejad, M., Xia, C., Hrton, M., Lee, K. T., Kim, A. S., Li, Q., Guzelturk, B., Kalousek, R., Xu, F., Cai, W., Lindenberg, A. M., Brongersma, M. L. 2023; 382 (6668): 299-305

  Abstract

  Understanding the ultrafast excitation and transport dynamics of plasmon-driven hot carriers is critical to the development of optoelectronics, photochemistry, and solar-energy harvesting. However, the ultrashort time and length scales associated with the behavior of these highly out-of-equilibrium carriers have impaired experimental verification of ab initio quantum theories. Here, we present an approach to studying plasmonic hot-carrier dynamics that analyzes the temporal waveform of coherent terahertz bursts radiated by photo-ejected hot carriers from designer nano-antennas with a broken symmetry. For ballistic carriers ejected from gold antennas, we find an ~11-femtosecond timescale composed of the plasmon lifetime and ballistic transport time. Polarization- and phase-sensitive detection of terahertz fields further grant direct access to their ballistic transport trajectory. Our approach opens explorations of ultrafast carrier dynamics in optically excited nanostructures.

  View details for DOI 10.1126/science.adj5612

  View details for PubMedID 37856614

• Nonthermal Bonding Origin of a Novel Photoexcited Lattice Instability in SnSe. Physical review letters Huang, Y., Teitelbaum, S., Yang, S., De la Peña, G., Sato, T., Chollet, M., Zhu, D., Niedziela, J. L., Bansal, D., May, A. F., Lindenberg, A. M., Delaire, O., Trigo, M., Reis, D. A. 2023; 131 (15): 156902

  Abstract

  Lattice dynamics measurements are often crucial tools for understanding how materials transform between different structures. We report time-resolved x-ray scattering-based measurements of the nonequilibrium lattice dynamics in SnSe, a monochalcogenide reported to host a novel photoinduced lattice instability. By fitting interatomic force models to the fluence dependent excited-state dispersion, we determine the nonthermal origin of the lattice instability to be dominated by changes of interatomic interactions along a bilayer-connecting bond, rather than of an intralayer bonding network that is of primary importance to the lattice instability in thermal equilibrium.

  View details for DOI 10.1103/PhysRevLett.131.156902

  View details for PubMedID 37897786

• Subnanosecond Reconfiguration of Ferroelectric Domains in Bismuth Ferrite. Advanced materials (Deerfield Beach, Fla.) Guzelturk, B., Yang, T., Liu, Y. C., Wei, C. C., Orenstein, G., Trigo, M., Zhou, T., Diroll, B. T., Holt, M. V., Wen, H., Chen, L. Q., Yang, J. C., Lindenberg, A. M. 2023: e2306029

  Abstract

  Domain switching is crucial for achieving desired functions in ferroic materials that are used in various applications. Fast control of domains at subnanosecond timescales remains a challenge despite its potential for high-speed operation in random-access memories, photonic, and nanoelectronic devices. In this work, ultrafast laser excitation is shown to transiently melt and reconfigure ferroelectric stripe domains in multiferroic bismuth ferrite on a timescale faster than 100 ps. This dynamic behavior is visualized by picosecond- and nanometer-resolved X-ray diffraction measurements as well as time-resolved X-ray diffuse scattering. The disordering of stripe domains is attributed to the screening of depolarization fields by photogenerated carriers resulting in the formation of charged domain walls, as supported by phase field simulations. Furthermore, the recovery of disordered domains exhibits subdiffusive growth on nanosecond timescales, with a nonequilibrium domain velocity reaching up to 10 m/s. These findings present a new approach to image and manipulate ferroelectric domains on subnanosecond timescales, which can be further extended into other photoferroic systems to modulate their electronic, optical, and magnetic properties beyond GHz frequencies. This approach could pave the way for high-speed ferroelectric data storage, computing and photonic applications in a range of photoferroics, and, more broadly, defines new approaches for visualizing the non-equilibrium dynamics of heterogeneous and disordered materials. This article is protected by copyright. All rights reserved.

  View details for DOI 10.1002/adma.202306029

  View details for PubMedID 37611614

• Giant room-temperature nonlinearities in a monolayer Janus topological semiconductor. Nature communications Shi, J., Xu, H., Heide, C., HuangFu, C., Xia, C., de Quesada, F., Shen, H., Zhang, T., Yu, L., Johnson, A., Liu, F., Shi, E., Jiao, L., Heinz, T., Ghimire, S., Li, J., Kong, J., Guo, Y., Lindenberg, A. M. 2023; 14 (1): 4953

  Abstract

  Nonlinear optical materials possess wide applications, ranging from terahertz and mid-infrared detection to energy harvesting. Recently, the correlations between nonlinear optical responses and certain topological properties, such as the Berry curvature and the quantum metric tensor, have attracted considerable interest. Here, we report giant room-temperature nonlinearities in non-centrosymmetric two-dimensional topological materials-the Janus transition metal dichalcogenides in the 1 T' phase, synthesized by an advanced atomic-layer substitution method. High harmonic generation, terahertz emission spectroscopy, and second harmonic generation measurements consistently show orders-of-the-magnitude enhancement in terahertz-frequency nonlinearities in 1 T' MoSSe (e.g., > 50 times higher than 2H MoS2 for 18th order harmonic generation; > 20 times higher than 2H MoS2 for terahertz emission). We link this giant nonlinear optical response to topological band mixing and strong inversion symmetry breaking due to the Janus structure. Our work defines general protocols for designing materials with large nonlinearities and heralds the applications of topological materials in optoelectronics down to the monolayer limit.

  View details for DOI 10.1038/s41467-023-40373-z

  View details for PubMedID 37587120

  View details for PubMedCentralID 8282873

• Ultrafast Wavefront Shaping via Space-Time Refraction ACS PHOTONICS Fan, Q., Shaltout, A. M., van de Groep, J., Brongersma, M. L., Lindenberg, A. M. 2023

  View details for DOI 10.1021/acsphotonics.3c00498

  View details for Web of Science ID 001021440200001

• Pulsed laser ejection of single-crystalline III-V solar cells from GaAs substrates CELL REPORTS PHYSICAL SCIENCE Reeves, B. A., Steiner, M. A., Carver, T. E., Zhang, Z., Lindenberg, A. M., Clemens, B. M. 2023; 4 (6)

  View details for DOI 10.1016/j.xcrp.2023.101449

  View details for Web of Science ID 001043591400001

• Understanding and Controlling Photothermal Responses in MXenes. Nano letters Guzelturk, B., Kamysbayev, V., Wang, D., Hu, H., Li, R., King, S. B., Reid, A. H., Lin, M., Wang, X., Walko, D. A., Zhang, X., Lindenberg, A., Talapin, D. V. 2023

  Abstract

  MXenes have the potential for efficient light-to-heat conversion in photothermal applications. To effectively utilize MXenes in such applications, it is important to understand the underlying nonequilibrium processes, including electron-phonon and phonon-phonon couplings. Here, we use transient electron and X-ray diffraction to investigate the heating and cooling of photoexcited MXenes at femtosecond to nanosecond time scales. Our results show extremely strong electron-phonon coupling in Ti3C2-based MXenes, resulting in lattice heating within a few hundred femtoseconds. We also systematically study heat dissipation in MXenes with varying film thicknesses, chemical surface terminations, flake sizes, and annealing conditions. We find that the thermal boundary conductance (TBC) governs the thermal relaxation in films thinner than the optical penetration depth. We achieve a 2-fold enhancement of the TBC, reaching 20 MW m-2 K-1, by controlling the flake size or chemical surface termination, which is promising for engineering heat dissipation in photothermal and thermoelectric applications of the MXenes.

  View details for DOI 10.1021/acs.nanolett.2c05001

  View details for PubMedID 36917456

• Ultrafast Optomechanical Strain in Layered GeS. Nano letters Luo, D., Zhang, B., Sie, E. J., Nyby, C. M., Fan, Q., Shen, X., Reid, A. H., Hoffmann, M. C., Weathersby, S., Wen, J., Qian, X., Wang, X., Lindenberg, A. M. 2023

  Abstract

  Strong coupling between light and mechanical strain forms the foundation for next-generation optical micro- and nano-electromechanical systems. Such optomechanical responses in two-dimensional materials present novel types of functionalities arising from the weak van der Waals bond between atomic layers. Here, by using structure-sensitive megaelectronvolt ultrafast electron diffraction, we report the experimental observation of optically driven ultrafast in-plane strain in the layered group IV monochalcogenide germanium sulfide (GeS). Surprisingly, the photoinduced structural deformation exhibits strain amplitudes of order 0.1% with a 10 ps fast response time and a significant in-plane anisotropy between zigzag and armchair crystallographic directions. Rather than arising due to heating, experimental and theoretical investigations suggest deformation potentials caused by electronic density redistribution and converse piezoelectric effects generated by photoinduced electric fields are the dominant contributors to the observed dynamic anisotropic strains. Our observations define new avenues for ultrafast optomechanical control and strain engineering within functional devices.

  View details for DOI 10.1021/acs.nanolett.2c05048

  View details for PubMedID 36898060

• Bidirectional phonon emission in two-dimensional heterostructures triggered by ultrafast charge transfer. Nature nanotechnology Sood, A., Haber, J. B., Carlström, J., Peterson, E. A., Barre, E., Georgaras, J. D., Reid, A. H., Shen, X., Zajac, M. E., Regan, E. C., Yang, J., Taniguchi, T., Watanabe, K., Wang, F., Wang, X., Neaton, J. B., Heinz, T. F., Lindenberg, A. M., da Jornada, F. H., Raja, A. 2022

  Abstract

  Photoinduced charge transfer in van der Waals heterostructures occurs on the 100 fs timescale despite weak interlayer coupling and momentum mismatch. However, little is understood about the microscopic mechanism behind this ultrafast process and the role of the lattice in mediating it. Here, using femtosecond electron diffraction, we directly visualize lattice dynamics in photoexcited heterostructures of WSe2/WS2 monolayers. Following the selective excitation of WSe2, we measure the concurrent heating of both WSe2 and WS2 on a picosecond timescale-an observation that is not explained by phonon transport across the interface. Using first-principles calculations, we identify a fast channel involving an electronic state hybridized across the heterostructure, enabling phonon-assisted interlayer transfer of photoexcited electrons. Phonons are emitted in both layers on the femtosecond timescale via this channel, consistent with the simultaneous lattice heating observed experimentally. Taken together, our work indicates strong electron-phonon coupling via layer-hybridized electronic states-a novel route to control energy transport across atomic junctions.

  View details for DOI 10.1038/s41565-022-01253-7

  View details for PubMedID 36543882

• Light-Driven Ultrafast Polarization Manipulation in a Relaxor Ferroelectric. Nano letters Park, S., Wang, B., Yang, T., Kim, J., Saremi, S., Zhao, W., Guzelturk, B., Sood, A., Nyby, C., Zajac, M., Shen, X., Kozina, M., Reid, A. H., Weathersby, S., Wang, X., Martin, L. W., Chen, L. Q., Lindenberg, A. M. 2022

  Abstract

  Relaxor ferroelectrics have been intensely studied for decades based on their unique electromechanical responses which arise from local structural heterogeneity involving polar nanoregions or domains. Here, we report first studies of the ultrafast dynamics and reconfigurability of the polarization in freestanding films of the prototypical relaxor 0.68PbMg1/3Nb2/3O3-0.32PbTiO3 (PMN-0.32PT) by probing its atomic-scale response via femtosecond-resolution, electron-scattering approaches. By combining these structural measurements with dynamic phase-field simulations, we show that femtosecond light pulses drive a change in both the magnitude and direction of the polarization vector within polar nanodomains on few-picosecond time scales. This study defines new opportunities for dynamic reconfigurable control of the polarization in nanoscale relaxor ferroelectrics.

  View details for DOI 10.1021/acs.nanolett.2c02706

  View details for PubMedID 36450036

• A room-temperature polarization-sensitive CMOS terahertz camera based on quantum-dot-enhanced terahertz-to-visible photon upconversion. Nature nanotechnology Shi, J., Yoo, D., Vidal-Codina, F., Baik, C. W., Cho, K. S., Nguyen, N. C., Utzat, H., Han, J., Lindenberg, A. M., Bulović, V., Bawendi, M. G., Peraire, J., Oh, S. H., Nelson, K. A. 2022

  Abstract

  Detection of terahertz (THz) radiation has many potential applications, but presently available detectors are limited in many aspects of their performance, including sensitivity, speed, bandwidth and operating temperature. Most do not allow the characterization of THz polarization states. Recent observation of THz-driven luminescence in quantum dots offers a possible detection mechanism via field-driven interdot charge transfer. We demonstrate a room-temperature complementary metal-oxide-semiconductor THz camera and polarimeter based on quantum-dot-enhanced THz-to-visible upconversion mechanism with optimized luminophore geometries and fabrication designs. Besides broadband and fast responses, the nanoslit-based sensor can detect THz pulses with peak fields as low as 10 kV cm-1. A related coaxial nanoaperture-type device shows a to-date-unexplored capability to simultaneously record the THz polarization state and field strength with similar sensitivity.

  View details for DOI 10.1038/s41565-022-01243-9

  View details for PubMedID 36329270

• Thickness- and Twist-Angle-Dependent Interlayer Excitons in Metal Monochalcogenide Heterostructures. ACS nano Zheng, W., Xiang, L., de Quesada, F. A., Augustin, M., Lu, Z., Wilson, M., Sood, A., Wu, F., Shcherbakov, D., Memaran, S., Baumbach, R. E., McCandless, G. T., Chan, J. Y., Liu, S., Edgar, J. H., Lau, C. N., Lui, C. H., Santos, E. J., Lindenberg, A., Smirnov, D., Balicas, L. 2022

  Abstract

  Interlayer excitons, or bound electron-hole pairs whose constituent quasiparticles are located in distinct stacked semiconducting layers, are being intensively studied in heterobilayers of two-dimensional semiconductors. They owe their existence to an intrinsic type-II band alignment between both layers that convert these into p-n junctions. Here, we unveil a pronounced interlayer exciton (IX) in heterobilayers of metal monochalcogenides, namely, gamma-InSe on epsilon-GaSe, whose pronounced emission is adjustable just by varying their thicknesses given their number of layers dependent direct band gaps. Time-dependent photoluminescense spectroscopy unveils considerably longer interlayer exciton lifetimes with respect to intralayer ones, thus confirming their nature. The linear Stark effect yields a bound electron-hole pair whose separation d is just (3.6 ± 0.1) A with d being very close to dSe = 3.4 A which is the calculated interfacial Se separation. The envelope of IX is twist-angle-dependent and describable by superimposed emissions that are nearly equally spaced in energy, as if quantized due to localization induced by the small moire periodicity. These heterostacks are characterized by extremely flat interfacial valence bands making them prime candidates for the observation of magnetism or other correlated electronic phases upon carrier doping.

  View details for DOI 10.1021/acsnano.2c07394

  View details for PubMedID 36257051

• Large Exchange Coupling Between Localized Spins and Topological Bands in Magnetic Topological Insulator MnBi2 Te4. Advanced materials (Deerfield Beach, Fla.) Padmanabhan, H., Stoica, V. A., Kim, P. K., Poore, M., Yang, T., Shen, X., Reid, A. H., Lin, M., Park, S., Yang, J., Hugo Wang, H., Koocher, N. Z., Puggioni, D., Georgescu, A. B., Min, L., Lee, S. H., Mao, Z., Rondinelli, J. M., Lindenberg, A. M., Chen, L., Wang, X., Averitt, R. D., Freeland, J. W., Gopalan, V. 2022: e2202841

  Abstract

  Magnetism in topological materials creates phases exhibiting quantized transport phenomena with potential technological applications. The emergence of such phases relies on strong interaction between localized spins and the topological bands, and the consequent formation of an exchange gap. However, this remains experimentally unquantified in intrinsic magnetic topological materials. Here, this interaction is quantified in MnBi2 Te4 , an intrinsic antiferromagnetic topological insulator. To achieve this, a multimodal ultrafast approach is employed to interrogate optically induced nonequilibrium spin dynamics. Momentum-resolved ultrafast electron scattering and magneto-optic measurements show that Bi-Te p-like states comprising the bulk topological bands demagnetize via electron-phonon scattering at picosecond timescales. Localized Mn 3d spins, probed by ultrafast resonant X-ray scattering, are found to disorder concurrently with the p-like spins, despite being energetically decoupled from the optical excitation. These results, together with atomistic simulations, reveal that the exchange coupling between localized spins and the bulk topological bands is at least 100 times larger than the primary superexchange interaction, implying an optimal exchange gap of at least 25 meV in the topological surface states. By directly quantifying this exchange coupling, the study validates the materials-by-design strategy of utilizing localized magnetic order to create and manipulate magnetic topological phases, spanning static to ultrafast timescales. This article is protected by copyright. All rights reserved.

  View details for DOI 10.1002/adma.202202841

  View details for PubMedID 36189841

• Non-Equilibrium Lattice Dynamics in Photo-Excited Two-Dimensional Perovskites. Advanced materials (Deerfield Beach, Fla.) Cuthriell, S. A., Panuganti, S., Laing, C. C., Quintero, M. A., Guzelturk, B., Yazdani, N., Traore, B., Brumberg, A., Malliakas, C. D., Lindenberg, A. M., Wood, V., Katan, C., Even, J., Zhang, X., Kanatzidis, M. G., Schaller, R. D. 2022: e2202709

  Abstract

  Interplay between structural and photophysical properties of metal halide perovskites is critical to their utility in optoelectronics, but limited understanding of lattice response upon excitation exists. Here, we investigate two-dimensional (2D) perovskites butylammonium lead iodide, (BA)2 PbI4 , and phenethylammonium lead iodide, (PEA)2 PbI4 , using ultrafast transient X-ray diffraction (TrXRD) as a function of optical excitation fluence to discern structural dynamics. Both powder X-ray diffraction (PXRD) and time-resolved photoluminescence (TrPL) linewidths exhibit narrowing over 1 ns following optical excitation for the fluence range studied, concurrent with slight red-shifting of the optical bandgaps. We attribute these observations to transient relaxation of distorted lead iodide octahedra stimulated mainly by electron-hole pair creation. The c axis expands up to 0.37% over hundreds of picoseconds; reflections sampling the a and b axes undergo one tenth of this expansion with the same timescale. Post-photo-excitation appearance of the (110) reflection in (BA)2 PbI4 would suggest a transient phase transition; however, through new single crystal XRD we find reflections that violate glide plane conditions in the reported Pbca structure and reassign the static structure space group as P21 21 21 ; with this we rule out non-equilibrium phase transition. These findings offer increased understanding of remarkable lattice response in 2D perovskites upon excitation. This article is protected by copyright. All rights reserved.

  View details for DOI 10.1002/adma.202202709

  View details for PubMedID 36062547

• Defect-driven anomalous transport in fast-ion conducting solid electrolytes. Nature materials Poletayev, A. D., Dawson, J. A., Islam, M. S., Lindenberg, A. M. 2022

  Abstract

  Solid-state ionic conduction is a key enabler of electrochemical energy storage and conversion. The mechanistic connections between material processing, defect chemistry, transport dynamics and practical performance are of considerable importance but remain incomplete. Here, inspired by studies of fluids and biophysical systems, we re-examine anomalous diffusion in the iconic two-dimensional fast-ion conductors, the beta- and beta-aluminas. Using large-scale simulations, we reproduce the frequency dependence of alternating-current ionic conductivity data. We show how the distribution of charge-compensating defects, modulated by processing, drives static and dynamic disorder and leads to persistent subdiffusive ion transport at macroscopic timescales. We deconvolute the effects of repulsions between mobile ions, the attraction between the mobile ions and charge-compensating defects, and geometric crowding on ionic conductivity. Finally, our characterization of memory effects in transport connects atomistic defect chemistry to macroscopic performance with minimal assumptions and enables mechanism-driven 'atoms-to-device' optimization of fast-ion conductors.

  View details for DOI 10.1038/s41563-022-01316-z

  View details for PubMedID 35902748

• Interlayer magnetophononic coupling in MnBi2Te4. Nature communications Padmanabhan, H., Poore, M., Kim, P. K., Koocher, N. Z., Stoica, V. A., Puggioni, D., Hugo Wang, H., Shen, X., Reid, A. H., Gu, M., Wetherington, M., Lee, S. H., Schaller, R. D., Mao, Z., Lindenberg, A. M., Wang, X., Rondinelli, J. M., Averitt, R. D., Gopalan, V. 2022; 13 (1): 1929

  Abstract

  The emergence of magnetism in quantum materials creates a platform to realize spin-based applications in spintronics, magnetic memory, and quantum information science. A key to unlocking new functionalities in these materials is the discovery of tunable coupling between spins and other microscopic degrees of freedom. We present evidence for interlayer magnetophononic coupling in the layered magnetic topological insulator MnBi2Te4. Employing magneto-Raman spectroscopy, we observe anomalies in phonon scattering intensities across magnetic field-driven phase transitions, despite the absence of discernible static structural changes. This behavior is a consequence of a magnetophononic wave-mixing process that allows for the excitation of zone-boundary phonons that are otherwise 'forbidden' by momentum conservation. Our microscopic model based on density functional theory calculations reveals that this phenomenon can be attributed to phonons modulating the interlayer exchange coupling. Moreover, signatures of magnetophononic coupling are also observed in the time domain through the ultrafast excitation and detection of coherent phonons across magnetic transitions. In light of the intimate connection between magnetism and topology in MnBi2Te4, the magnetophononic coupling represents an important step towards coherent on-demand manipulation of magnetic topological phases.

  View details for DOI 10.1038/s41467-022-29545-5

  View details for PubMedID 35396393

• Laser-induced patterning for a diffraction grating using the phase change material of Ge2Sb2Te5 (GST) as a spatial light modulator in X-ray optics: a proof of concept OPTICAL MATERIALS EXPRESS Park, J., Zalden, P., Ng, E., Johnston, S., Fong, S. W., Chang, C., Tassone, C. J., Van Campen, D., Mok, W., Mabuchi, H., Wong, H., Shen, Z., Lindenberg, A. M., Sakdinawat, A. 2022; 12 (4): 1408-1416

  View details for DOI 10.1364/OME.451534

  View details for Web of Science ID 000790447300002

• Observation of a Novel Lattice Instability in Ultrafast Photoexcited SnSe PHYSICAL REVIEW X Huang, Y., Yang, S., Teitelbaum, S., De la Pena, G., Sato, T., Chollet, M., Zhu, D., Niedziela, J. L., Bansal, D., May, A. F., Lindenberg, A. M., Delaire, O., Reis, D. A., Trigo, M. 2022; 12 (1)

  View details for DOI 10.1103/PhysRevX.12.011029

  View details for Web of Science ID 000761380600001

• Testing the data framework for an AI algorithm in preparation for high data rate X-ray facilities Chen, H., Chitturi, S. R., Plumley, R., Shen, L., Drucker, N. C., Burdet, N., Peng, C., Mardanya, S., Ratner, D., Mishra, A., Yoon, C., Song, S., Chollet, M., Fabbris, G., Dunne, M., Nelson, S., Li, M., Lindenberg, A., Jia, C., Nashed, Y., Bansil, A., Chowdhury, S., Feiguin, A. E., Turner, J. J., Thayer, J. B., IEEE IEEE. 2022: 1-9

  View details for DOI 10.1109/XLOOP56614.2022.00006

  View details for Web of Science ID 000968746500001

• Dynamically Tunable Terahertz Emission Enabled by Anomalous Optical Phonon Responses in Lead Telluride ACS PHOTONICS Guzelturk, B., Trigo, M., Delaire, O., Reis, D. A., Lindenberg, A. M. 2021; 8 (12): 3633-3640

  View details for DOI 10.1021/acsphotonics.1c01291

  View details for Web of Science ID 000753681400025

• Inq, a Modern GPU-Accelerated Computational Framework for (Time-Dependent) Density Functional Theory. Journal of chemical theory and computation Andrade, X., Pemmaraju, C. D., Kartsev, A., Xiao, J., Lindenberg, A., Rajpurohit, S., Tan, L. Z., Ogitsu, T., Correa, A. A. 2021

  Abstract

  We present inq, a new implementation of density functional theory (DFT) and time-dependent DFT (TDDFT) written from scratch to work on graphic processing units (GPUs). Besides GPU support, inq makes use of modern code design features and takes advantage of newly available hardware. By designing the code around algorithms, rather than against specific implementations and numerical libraries, we aim to provide a concise and modular code. The result is a fairly complete DFT/TDDFT implementation in roughly 12 000 lines of open-source C++ code representing a modular platform for community-driven application development on emerging high-performance computing architectures.

  View details for DOI 10.1021/acs.jctc.1c00562

  View details for PubMedID 34726888

• Twist-Angle-Dependent Ultrafast Charge Transfer in MoS2-Graphene van der Waals Heterostructures. Nano letters Luo, D., Tang, J., Shen, X., Ji, F., Yang, J., Weathersby, S., Kozina, M. E., Chen, Z., Xiao, J., Ye, Y., Cao, T., Zhang, G., Wang, X., Lindenberg, A. M. 2021

  Abstract

  Vertically stacked transition metal dichalcogenide-graphene heterostructures provide a platform for novel optoelectronic applications with high photoresponse speeds. Photoinduced nonequilibrium carrier and lattice dynamics in such heterostructures underlie these applications but have not been understood. In particular, the dependence of these photoresponses on the twist angle, a key tuning parameter, remains elusive. Here, using ultrafast electron diffraction, we report the simultaneous visualization of charge transfer and electron-phonon coupling in MoS2-graphene heterostructures with different stacking configurations. We find that the charge transfer timescale from MoS2 to graphene varies strongly with twist angle, becoming faster for smaller twist angles, and show that the relaxation timescale is significantly shorter in a heterostructure as compared to a monolayer. These findings illustrate that twist angle constitutes an additional tuning knob for interlayer charge transfer in heterobilayers and deepen our understanding of fundamental photophysical processes in heterostructures, of importance for future applications in optoelectronics and light harvesting.

  View details for DOI 10.1021/acs.nanolett.1c02356

  View details for PubMedID 34529439

• Dynamic structural views in solar energy materials by femtosecond electron diffraction MRS BULLETIN Guzelturk, B., Lindenberg, A. 2021

  View details for DOI 10.1557/s43577-021-00151-y

  View details for Web of Science ID 000684464200003

• Direct observation of ultrafast hydrogen bond strengthening in liquid water. Nature Yang, J., Dettori, R., Nunes, J. P., List, N. H., Biasin, E., Centurion, M., Chen, Z., Cordones, A. A., Deponte, D. P., Heinz, T. F., Kozina, M. E., Ledbetter, K., Lin, M., Lindenberg, A. M., Mo, M., Nilsson, A., Shen, X., Wolf, T. J., Donadio, D., Gaffney, K. J., Martinez, T. J., Wang, X. 2021; 596 (7873): 531-535

  Abstract

  Water is one of the most important, yet least understood, liquids in nature. Many anomalous properties of liquid water originate from its well-connected hydrogen bond network1, including unusually efficient vibrational energy redistribution and relaxation2. An accurate description of the ultrafast vibrational motion of water molecules is essential for understanding the nature of hydrogen bonds and many solution-phase chemical reactions. Most existing knowledge of vibrational relaxation in water is built upon ultrafast spectroscopy experiments2-7. However, these experiments cannot directly resolve the motion of the atomic positions and require difficult translation of spectral dynamics into hydrogen bond dynamics. Here, we measure the ultrafast structural response to the excitation of the OH stretching vibration in liquid water with femtosecond temporal and atomic spatial resolution using liquid ultrafast electron scattering. We observed a transient hydrogen bond contraction of roughly 0.04A on a timescale of 80 femtoseconds, followed by a thermalization on a timescale of approximately 1 picosecond. Molecular dynamics simulations reveal the need to treat the distribution of the shared proton in the hydrogen bond quantum mechanically to capture the structural dynamics on femtosecond timescales. Our experiment and simulations unveil the intermolecular character of the water vibration preceding the relaxation of the OH stretch.

  View details for DOI 10.1038/s41586-021-03793-9

  View details for PubMedID 34433948

• Highly Efficient Uniaxial In-Plane Stretching of a 2D Material via Ion Insertion. Advanced materials (Deerfield Beach, Fla.) Muscher, P. K., Rehn, D. A., Sood, A., Lim, K., Luo, D., Shen, X., Zajac, M., Lu, F., Mehta, A., Li, Y., Wang, X., Reed, E. J., Chueh, W. C., Lindenberg, A. M. 2021: e2101875

  Abstract

  On-chip dynamic strain engineering requires efficient micro-actuators that can generate large in-plane strains. Inorganic electrochemical actuators are unique in that they are driven by low voltages (1V) and produce considerable strains (1%). However, actuation speed and efficiency are limited by mass transport of ions. Minimizing the number of ions required to actuate is thus key to enabling useful "straintronic" devices. Here, it is shown that the electrochemical intercalation of exceptionally few lithium ions into WTe2 causes large anisotropic in-plane strain: 5% in one in-plane direction and 0.1% in the other. This efficient stretching of the 2D WTe2 layers contrasts to intercalation-induced strains in related materials which are predominantly in the out-of-plane direction. The unusual actuation of Lix WTe2 is linked to the formation of a newly discovered crystallographic phase, referred to as Td', with an exotic atomic arrangement. On-chip low-voltage (<0.2V) control is demonstrated over the transition to the novel phase and its composition. Within the Td'-Li0.5- delta WTe2 phase, a uniaxial in-plane strain of 1.4% is achieved with a change of delta of only 0.075. This makes the in-plane chemical expansion coefficient of Td'-Li0.5-delta WTe2 far greater than of any other single-phase material, enabling fast and efficient planar electrochemical actuation.

  View details for DOI 10.1002/adma.202101875

  View details for PubMedID 34331368

• Universal phase dynamics in VO2 switches revealed by ultrafast operando diffraction SCIENCE Sood, A., Shen, X., Shi, Y., Kumar, S., Park, S., Zajac, M., Sun, Y., Chen, L., Ramanathan, S., Wang, X., Chueh, W. C., Lindenberg, A. M. 2021; 373 (6552): 352-+

  View details for DOI 10.1126/science.abc0652

  View details for Web of Science ID 000679214500039

• Universal phase dynamics in VO2 switches revealed by ultrafast operando diffraction. Science (New York, N.Y.) Sood, A., Shen, X., Shi, Y., Kumar, S., Park, S. J., Zajac, M., Sun, Y., Chen, L. Q., Ramanathan, S., Wang, X., Chueh, W. C., Lindenberg, A. M. 2021; 373 (6552): 352-355

  Abstract

  Understanding the pathways and time scales underlying electrically driven insulator-metal transitions is crucial for uncovering the fundamental limits of device operation. Using stroboscopic electron diffraction, we perform synchronized time-resolved measurements of atomic motions and electronic transport in operating vanadium dioxide (VO2) switches. We discover an electrically triggered, isostructural state that forms transiently on microsecond time scales, which is shown by phase-field simulations to be stabilized by local heterogeneities and interfacial interactions between the equilibrium phases. This metastable phase is similar to that formed under photoexcitation within picoseconds, suggesting a universal transformation pathway. Our results establish electrical excitation as a route for uncovering nonequilibrium and metastable phases in correlated materials, opening avenues for engineering dynamical behavior in nanoelectronics.

  View details for DOI 10.1126/science.abc0652

  View details for PubMedID 34437156

• Electrochemical ion insertion from the atomic to the device scale NATURE REVIEWS MATERIALS Sood, A., Poletayev, A. D., Cogswell, D. A., Csernica, P. M., Mefford, J., Fraggedakis, D., Toney, M. F., Lindenberg, A. M., Bazant, M. Z., Chueh, W. C. 2021

  View details for DOI 10.1038/s41578-021-00314-y

  View details for Web of Science ID 000653598000004

• Nanoscale Disorder Generates Subdiffusive Heat Transport in Self-Assembled Nanocrystal Films. Nano letters Utterback, J. K., Sood, A., Coropceanu, I., Guzelturk, B., Talapin, D. V., Lindenberg, A. M., Ginsberg, N. S. 2021

  Abstract

  Investigating the impact of nanoscale heterogeneity on heat transport requires a spatiotemporal probe of temperature on the length and time scales intrinsic to heat navigating nanoscale defects. Here, we use stroboscopic optical scattering microscopy to visualize nanoscale heat transport in disordered films of gold nanocrystals. We find that heat transport appears subdiffusive at the nanoscale. Finite element simulations show that tortuosity of the heat flow underlies the subdiffusive transport, owing to a distribution of nonconductive voids. Thus, while heat travels diffusively through contiguous regions of the film, the tortuosity causes heat to navigate circuitous pathways that make the observed mean-squared expansion of an initially localized temperature distribution appear subdiffusive on length scales comparable to the voids. Our approach should be broadly applicable to uncover the impact of both designed and unintended heterogeneities in a wide range of materials and devices that can affect more commonly used spatially averaged thermal transport measurements.

  View details for DOI 10.1021/acs.nanolett.1c00413

  View details for PubMedID 33872014

• Subterahertz collective dynamics of polar vortices. Nature Li, Q., Stoica, V. A., Pasciak, M., Zhu, Y., Yuan, Y., Yang, T., McCarter, M. R., Das, S., Yadav, A. K., Park, S., Dai, C., Lee, H. J., Ahn, Y., Marks, S. D., Yu, S., Kadlec, C., Sato, T., Hoffmann, M. C., Chollet, M., Kozina, M. E., Nelson, S., Zhu, D., Walko, D. A., Lindenberg, A. M., Evans, P. G., Chen, L., Ramesh, R., Martin, L. W., Gopalan, V., Freeland, J. W., Hlinka, J., Wen, H. 2021; 592 (7854): 376–80

  Abstract

  The collective dynamics of topological structures1-6 are of interest from both fundamental and applied perspectives. For example, studies of dynamical properties of magnetic vortices and skyrmions3,4 have not only deepened our understanding of many-body physics but also offered potential applications in data processing and storage7. Topological structures constructed from electrical polarization, rather than electron spin, have recently been realized in ferroelectric superlattices5,6, and these are promising for ultrafast electric-field control of topological orders. However, little is known about the dynamics underlying the functionality of such complex extended nanostructures. Here, using terahertz-field excitation and femtosecond X-ray diffraction measurements, we observe ultrafast collective polarization dynamics that are unique to polar vortices, with orders-of-magnitude higher frequencies and smaller lateral size than those of experimentally realized magnetic vortices3. A previously unseen tunable mode, hereafter referred to as a vortexon, emerges in the form of transient arrays of nanoscale circular patterns of atomic displacements, which reverse their vorticity on picosecond timescales. Its frequency is considerably reduced (softened) at a critical strain, indicating a condensation (freezing) of structural dynamics. We use first-principles-based atomistic calculations and phase-field modelling to reveal the microscopic atomic arrangements and corroborate the frequencies of the vortex modes. The discovery of subterahertz collective dynamics in polar vortices opens opportunities for electric-field-driven data processing in topological structures with ultrahigh speed and density.

  View details for DOI 10.1038/s41586-021-03342-4

  View details for PubMedID 33854251

• Dynamic lattice distortions driven by surface trapping in semiconductor nanocrystals. Nature communications Guzelturk, B., Cotts, B. L., Jasrasaria, D., Philbin, J. P., Hanifi, D. A., Koscher, B. A., Balan, A. D., Curling, E., Zajac, M., Park, S., Yazdani, N., Nyby, C., Kamysbayev, V., Fischer, S., Nett, Z., Shen, X., Kozina, M. E., Lin, M., Reid, A. H., Weathersby, S. P., Schaller, R. D., Wood, V., Wang, X., Dionne, J. A., Talapin, D. V., Alivisatos, A. P., Salleo, A., Rabani, E., Lindenberg, A. M. 2021; 12 (1): 1860

  Abstract

  Nonradiative processes limit optoelectronic functionality of nanocrystals and curb their device performance. Nevertheless, the dynamic structural origins of nonradiative relaxations in such materials are not understood. Here, femtosecond electron diffraction measurements corroborated by atomistic simulations uncover transient lattice deformations accompanying radiationless electronic processes in colloidal semiconductor nanocrystals. Investigation of the excitation energy dependence in a core/shell system shows that hot carriers created by a photon energy considerably larger than the bandgap induce structural distortions at nanocrystal surfaces on few picosecond timescales associated with the localization of trapped holes. On the other hand, carriers created by a photon energy close to the bandgap of the core in the same system result in transient lattice heating that occurs on a much longer 200 picosecond timescale, dominated by an Auger heating mechanism. Elucidation of the structural deformations associated with the surface trapping of hot holes provides atomic-scale insights into the mechanisms deteriorating optoelectronic performance and a pathway towards minimizing these losses in nanocrystal devices.

  View details for DOI 10.1038/s41467-021-22116-0

  View details for PubMedID 33767138

• Visualization of dynamic polaronic strain fields in hybrid lead halide perovskites. Nature materials Guzelturk, B., Winkler, T., Van de Goor, T. W., Smith, M. D., Bourelle, S. A., Feldmann, S., Trigo, M., Teitelbaum, S. W., Steinruck, H., de la Pena, G. A., Alonso-Mori, R., Zhu, D., Sato, T., Karunadasa, H. I., Toney, M. F., Deschler, F., Lindenberg, A. M. 2021

  Abstract

  Excitation localization involving dynamic nanoscale distortions is a central aspect of photocatalysis1, quantum materials2 and molecular optoelectronics3. Experimental characterization of such distortions requires techniques sensitive to the formation of point-defect-like local structural rearrangements in real time. Here, we visualize excitation-induced strain fields in a prototypical member of the lead halide perovskites4 via femtosecond resolution diffuse X-ray scattering measurements. This enables momentum-resolved phonon spectroscopy of the locally distorted structure and reveals radially expanding nanometre-scale strain fields associated with the formation and relaxation of polarons in photoexcited perovskites. Quantitative estimates of the magnitude and shape of this polaronic distortion are obtained, providing direct insights into the dynamic structural distortions that occur in these materials5-9. Optical pump-probe reflection spectroscopy corroborates these results and shows how these large polaronic distortions transiently modify the carrier effective mass, providing a unified picture of the coupled structural and electronic dynamics that underlie the optoelectronic functionality of the hybrid perovskites.

  View details for DOI 10.1038/s41563-020-00865-5

  View details for PubMedID 33398119

• Carrier-specific dynamics in 2H-MoTe2 observed by femtosecond soft x-ray absorption spectroscopy using an x-ray free-electron laser. Structural dynamics (Melville, N.Y.) Britz, A., Attar, A. R., Zhang, X., Chang, H., Nyby, C., Krishnamoorthy, A., Park, S. H., Kwon, S., Kim, M., Nordlund, D., Sainio, S., Heinz, T. F., Leone, S. R., Lindenberg, A. M., Nakano, A., Ajayan, P., Vashishta, P., Fritz, D., Lin, M., Bergmann, U. 2021; 8 (1): 014501

  Abstract

  Femtosecond carrier dynamics in layered 2H-MoTe2 semiconductor crystals have been investigated using soft x-ray transient absorption spectroscopy at the x-ray free-electron laser (XFEL) of the Pohang Accelerator Laboratory. Following above-bandgap optical excitation of 2H-MoTe2, the photoexcited hole distribution is directly probed via short-lived transitions from the Te 3d 5/2 core level (M5-edge, 572-577eV) to transiently unoccupied states in the valence band. The optically excited electrons are separately probed via the reduced absorption probability at the Te M5-edge involving partially occupied states of the conduction band. A 400±110 fs delay is observed between this transient electron signal near the conduction band minimum compared to higher-lying states within the conduction band, which we assign to hot electron relaxation. Additionally, the transient absorption signals below and above the Te M5 edge, assigned to photoexcited holes and electrons, respectively, are observed to decay concomitantly on a 1-2 ps timescale, which is interpreted as electron-hole recombination. The present work provides a benchmark for applications of XFELs for soft x-ray absorption studies of carrier-specific dynamics in semiconductors, and future opportunities enabled by this method are discussed.

  View details for DOI 10.1063/4.0000048

  View details for PubMedID 33511247

• Steam-created grain boundaries for methane C-H activation in palladium catalysts. Science (New York, N.Y.) Huang, W., Johnston-Peck, A. C., Wolter, T., Yang, W. D., Xu, L., Oh, J., Reeves, B. A., Zhou, C., Holtz, M. E., Herzing, A. A., Lindenberg, A. M., Mavrikakis, M., Cargnello, M. 2021; 373 (6562): 1518-1523

  Abstract

  [Figure: see text].

  View details for DOI 10.1126/science.abj5291

  View details for PubMedID 34554810

• Synthesis of Macroscopic Single Crystals of Ge2Sb2Te5 via Single-Shot Femtosecond Optical Excitation CRYSTAL GROWTH & DESIGN Zajac, M., Sood, A., Kim, T. R., Mo, M., Kozina, M., Park, S., Shen, X., Guzelturk, B., Lin, M., Yang, J., Weathersby, S., Wang, X., Lindenberg, A. M. 2020; 20 (10): 6660–67

  View details for DOI 10.1021/acs.cgd.0c00816

  View details for Web of Science ID 000580511100042

• Acceleration of Crystallization Kinetics in Ge-Sb-Te-Based Phase-Change Materials by Substitution of Ge by Sn ADVANCED FUNCTIONAL MATERIALS Zalden, P., Koch, C., Paulsen, M., Esters, M., Johnson, D. C., Wuttig, M., Lindenberg, A. M., Bensch, W. 2020

  View details for DOI 10.1002/adfm.202004803

  View details for Web of Science ID 000573010600001

• Bulk and Nanocrystalline Cesium Lead-Halide Perovskites as Seen by Halide Magnetic Resonance. ACS central science Piveteau, L., Aebli, M., Yazdani, N., Millen, M., Korosec, L., Krieg, F., Benin, B. M., Morad, V., Piveteau, C., Shiroka, T., Comas-Vives, A., Coperet, C., Lindenberg, A. M., Wood, V., Verel, R., Kovalenko, M. V. 2020; 6 (7): 1138–49

  Abstract

  Lead-halide perovskites increasingly mesmerize researchers because they exhibit a high degree of structural defects and dynamics yet nonetheless offer an outstanding (opto)electronic performance on par with the best examples of structurally stable and defect-free semiconductors. This highly unusual feature necessitates the adoption of an experimental and theoretical mindset and the reexamination of techniques that may be uniquely suited to understand these materials. Surprisingly, the suite of methods for the structural characterization of these materials does not commonly include nuclear magnetic resonance (NMR) spectroscopy. The present study showcases both the utility and versatility of halide NMR and NQR (nuclear quadrupole resonance) for probing the structure and structural dynamics of CsPbX3 (X = Cl, Br, I), in both bulk and nanocrystalline forms. The strong quadrupole couplings, which originate from the interaction between the large quadrupole moments of, e.g., the 35Cl, 79Br, and 127I nuclei, and the local electric-field gradients, are highly sensitive to subtle structural variations, both static and dynamic. The quadrupole interaction can resolve structural changes with accuracies commensurate with synchrotron X-ray diffraction and scattering. It is shown that space-averaged site-disorder is greatly enhanced in the nanocrystals compared to the bulk, while the dynamics of nuclear spin relaxation indicates enhanced structural dynamics in the nanocrystals. The findings from NMR and NQR were corroborated by ab initio molecular dynamics, which point to the role of the surface in causing the radial strain distribution and disorder. These findings showcase a great synergy between solid-state NMR or NQR and molecular dynamics simulations in shedding light on the structure of soft lead-halide semiconductors.

  View details for DOI 10.1021/acscentsci.0c00587

  View details for PubMedID 32724848

• Visualizing Energy Transfer at Buried Interfaces in Layered Materials Using Picosecond X-Rays ADVANCED FUNCTIONAL MATERIALS Nyby, C., Sood, A., Zalden, P., Gabourie, A. J., Muscher, P., Rhodes, D., Mannebach, E., Corbett, J., Mehta, A., Pop, E., Heinz, T. F., Lindenberg, A. M. 2020

  View details for DOI 10.1002/adfm.202002282

  View details for Web of Science ID 000544093300001

• Berry curvature memory through electrically driven stacking transitions NATURE PHYSICS Xiao, J., Wang, Y., Wang, H., Pemmaraju, C. D., Wang, S., Muscher, P., Sie, E. J., Nyby, C. M., Devereaux, T. P., Qian, X., Zhang, X., Lindenberg, A. M. 2020

  View details for DOI 10.1038/s41567-020-0947-0

  View details for Web of Science ID 000544166500001

• Nonequilibrium Thermodynamics of Colloidal Gold Nanocrystals Monitored by Ultrafast Electron Diffraction and Optical Scattering Microscopy. ACS nano Guzelturk, B. n., Utterback, J. K., Coropceanu, I. n., Kamysbayev, V. n., Janke, E. M., Zajac, M. n., Yazdani, N. n., Cotts, B. L., Park, S. n., Sood, A. n., Lin, M. F., Reid, A. H., Kozina, M. E., Shen, X. n., Weathersby, S. P., Wood, V. n., Salleo, A. n., Wang, X. n., Talapin, D. V., Ginsberg, N. S., Lindenberg, A. M. 2020

  Abstract

  Metal nanocrystals exhibit important optoelectronic and photocatalytic functionalities in response to light. These dynamic energy conversion processes have been commonly studied by transient optical probes to date, but an understanding of the atomistic response following photoexcitation has remained elusive. Here, we use femtosecond resolution electron diffraction to investigate transient lattice responses in optically excited colloidal gold nanocrystals, revealing the effects of nanocrystal size and surface ligands on the electron-phonon coupling and thermal relaxation dynamics. First, we uncover a strong size effect on the electron-phonon coupling, which arises from reduced dielectric screening at the nanocrystal surfaces and prevails independent of the optical excitation mechanism (i.e., inter- and intraband). Second, we find that surface ligands act as a tuning parameter for hot carrier cooling. Particularly, gold nanocrystals with thiol-based ligands show significantly slower carrier cooling as compared to amine-based ligands under intraband optical excitation due to electronic coupling at the nanocrystal/ligand interfaces. Finally, we spatiotemporally resolve thermal transport and heat dissipation in photoexcited nanocrystal films by combining electron diffraction with stroboscopic elastic scattering microscopy. Taken together, we resolve the distinct thermal relaxation time scales ranging from 1 ps to 100 ns associated with the multiple interfaces through which heat flows at the nanoscale. Our findings provide insights into optimization of gold nanocrystals and their thin films for photocatalysis and thermoelectric applications.

  View details for DOI 10.1021/acsnano.0c00673

  View details for PubMedID 32208676

• Anisotropic structural dynamics of monolayer crystals revealed by femtosecond surface X-ray scattering NATURE PHOTONICS Tung, I., Krishnamoorthy, A., Sadasivam, S., Zhou, H., Zhang, Q., Seyler, K. L., Clark, G., Mannebach, E. M., Nyby, C., Ernst, F., Zhu, D., Glownia, J. M., Kozina, M. E., Song, S., Nelson, S., Kumazoe, H., Shimojo, F., Kalia, R. K., Vashishta, P., Darancet, P., Heinz, T. F., Nakano, A., Xu, X., Lindenberg, A. M., Wen, H. 2019; 13 (6): 425-+

  View details for DOI 10.1038/s41566-019-0387-5

  View details for Web of Science ID 000468752300020

• Molecule-like trap states in halide perovskites: From solar-cell absorbers to white-light emitters Smith, M., Jaffe, A., Lindenberg, A., Karunadasa, H. AMER CHEMICAL SOC. 2019

  View details for Web of Science ID 000478861201710

• Recording interfacial currents on the subnanometer length and femtosecond time scale by terahertz emission. Science advances Ma, E. Y., Guzelturk, B., Li, G., Cao, L., Shen, Z., Lindenberg, A. M., Heinz, T. F. 2019; 5 (2): eaau0073

  Abstract

  Electron dynamics at interfaces is a subject of great scientific interest and technological importance. Detailed understanding of such dynamics requires access to the angstrom length scale defining interfaces and the femtosecond time scale characterizing interfacial motion of electrons. In this context, the most precise and general way to remotely measure charge dynamics is through the transient current flow and the associated electromagnetic radiation. Here, we present quantitative measurements of interfacial currents on the subnanometer length and femtosecond time scale by recording the emitted terahertz radiation following ultrafast laser excitation. We apply this method to interlayer charge transfer in heterostructures of two transition metal dichalcogenide monolayers less than 0.7 nm apart. We find that charge relaxation and separation occur in less than 100 fs. This approach allows us to unambiguously determine the direction of current flow, to demonstrate a charge transfer efficiency of order unity, and to characterize saturation effects.

  View details for PubMedID 30783622

• Recording interfacial currents on the subnanometer length and femtosecond time scale by terahertz emission SCIENCE ADVANCES Ma, E., Guzelturk, B., Li, G., Cao, L., Shen, Z., Lindenberg, A. M., Heinz, T. F. 2019; 5 (2)

  View details for DOI 10.1126/sciadv.aau0073

  View details for Web of Science ID 000460145700014

• Femtosecond x-ray diffraction reveals a liquid-liquid phase transition in phase-change materials. Science (New York, N.Y.) Zalden, P. n., Quirin, F. n., Schumacher, M. n., Siegel, J. n., Wei, S. n., Koc, A. n., Nicoul, M. n., Trigo, M. n., Andreasson, P. n., Enquist, H. n., Shu, M. J., Pardini, T. n., Chollet, M. n., Zhu, D. n., Lemke, H. n., Ronneberger, I. n., Larsson, J. n., Lindenberg, A. M., Fischer, H. E., Hau-Riege, S. n., Reis, D. A., Mazzarello, R. n., Wuttig, M. n., Sokolowski-Tinten, K. n. 2019; 364 (6445): 1062–67

  Abstract

  In phase-change memory devices, a material is cycled between glassy and crystalline states. The highly temperature-dependent kinetics of its crystallization process enables application in memory technology, but the transition has not been resolved on an atomic scale. Using femtosecond x-ray diffraction and ab initio computer simulations, we determined the time-dependent pair-correlation function of phase-change materials throughout the melt-quenching and crystallization process. We found a liquid-liquid phase transition in the phase-change materials Ag4In3Sb67Te26 and Ge15Sb85 at 660 and 610 kelvin, respectively. The transition is predominantly caused by the onset of Peierls distortions, the amplitude of which correlates with an increase of the apparent activation energy of diffusivity. This reveals a relationship between atomic structure and kinetics, enabling a systematic optimization of the memory-switching kinetics.

  View details for DOI 10.1126/science.aaw1773

  View details for PubMedID 31197008

• An Ultrafast Symmetry Switch in a Weyl Semimetal Nature Sie, E. J., et al 2019; 565, 61

  View details for DOI 10.1038/s41586-018-0809-4

• Terahertz Kerr Effect in beta-Alumina Ion Conductors Poletayev, A. D., Hoffmann, M. C., Teitelbaum, S. W., Trigo, M., Chueh, W. C., Lindenberg, A. M., IEEE IEEE. 2019

  View details for Web of Science ID 000482226301054

• THz-Pump UED-Probe on a Topological Weyl Semimetal Sie, E. J., Nyby, C. M., Pemmaraju, C. D., Park, S., Shen, X., Yang, J., Hoffmann, M. C., Ofori-Okai, B. K., Li, R., Reid, A. H., Weathersby, S., Mannebach, E., Finney, N., Rhodes, D., Chenet, D., Antony, A., Balicas, L., Hone, J., Devereaux, T. P., Heinz, T. F., Wang, X., Lindenberg, A. M., IEEE IEEE. 2019

  View details for Web of Science ID 000482226301297

• Monitoring Charge Separation Dynamics Using THz Emission Spectroscopy Guzelturk, B., Ma, E., Li, G., Cao, L., Shen, Z., Heinz, T., Lindenberg, A., IEEE IEEE. 2019

  View details for Web of Science ID 000482226301162

• Light-Induced Currents at Domain Walls in Multiferroic BiFeO3. Nano letters Guzelturk, B. n., Mei, A. B., Zhang, L. n., Tan, L. Z., Donahue, P. n., Singh, A. G., Schlom, D. G., Martin, L. W., Lindenberg, A. M. 2019

  Abstract

  Multiferroic BiFeO3 (BFO) films with spontaneously formed periodic stripe domains can generate above-gap open circuit voltages under visible light illumination; nevertheless the underlying mechanism behind this intriguing optoelectronic response has not been understood to date. Here, we make contact-free measurements of light-induced currents in epitaxial BFO films via detecting terahertz radiation emanated by these currents, enabling a direct probe of the intrinsic charge separation mechanisms along with quantitative measurements of the current amplitudes and their directions. In the periodic stripe samples, we find that the net photocurrent is dominated by the charge separation across the domain walls, whereas in the monodomain samples the photovoltaic response arises from a bulk shift current associated with the non-centrosymmetry of the crystal. The peak current amplitude driven by the charge separation at the domain walls is found to be 2 orders of magnitude higher than the bulk shift current response, indicating the prominent role of domain walls acting as nanoscale junctions to efficiently separate photogenerated charges in the stripe domain BFO films. These findings show that domain-wall-engineered BFO thin films offer exciting prospects for ferroelectric-based optoelectronics, as well as bias-free strong terahertz emitters.

  View details for DOI 10.1021/acs.nanolett.9b03484

  View details for PubMedID 31746607

• An ultrafast symmetry switch in a Weyl semimetal. Nature Sie, E. J., Nyby, C. M., Pemmaraju, C. D., Park, S. J., Shen, X. n., Yang, J. n., Hoffmann, M. C., Ofori-Okai, B. K., Li, R. n., Reid, A. H., Weathersby, S. n., Mannebach, E. n., Finney, N. n., Rhodes, D. n., Chenet, D. n., Antony, A. n., Balicas, L. n., Hone, J. n., Devereaux, T. P., Heinz, T. F., Wang, X. n., Lindenberg, A. M. 2019; 565 (7737): 61–66

  Abstract

  Topological quantum materials exhibit fascinating properties1-3, with important applications for dissipationless electronics and fault-tolerant quantum computers4,5. Manipulating the topological invariants in these materials would allow the development of topological switching applications analogous to switching of transistors6. Lattice strain provides the most natural means of tuning these topological invariants because it directly modifies the electron-ion interactions and potentially alters the underlying crystalline symmetry on which the topological properties depend7-9. However, conventional means of applying strain through heteroepitaxial lattice mismatch10 and dislocations11 are not extendable to controllable time-varying protocols, which are required in transistors. Integration into a functional device requires the ability to go beyond the robust, topologically protected properties of materials and to manipulate the topology at high speeds. Here we use crystallographic measurements by relativistic electron diffraction to demonstrate that terahertz light pulses can be used to induce terahertz-frequency interlayer shear strain with large strain amplitude in the Weyl semimetal WTe2, leading to a topologically distinct metastable phase. Separate nonlinear optical measurements indicate that this transition is associated with a symmetry change to a centrosymmetric, topologically trivial phase. We further show that such shear strain provides an ultrafast, energy-efficient way of inducing robust, well separated Weyl points or of annihilating all Weyl points of opposite chirality. This work demonstrates possibilities for ultrafast manipulation of the topological properties of solids and for the development of a topological switch operating at terahertz frequencies.

  View details for PubMedID 30602749

• Atomic-scale imaging of ultrafast materials dynamics MRS BULLETIN Flannigan, D. J., Lindenberg, A. M. 2018; 43 (7): 485–90

  View details for DOI 10.1557/mrs.2018.146

  View details for Web of Science ID 000445175700009

• Obtaining white light from layered perovskites Smith, M., Jaffe, A., Dohner, E., Lindenberg, A., Karunadasa, H. AMER CHEMICAL SOC. 2018

  View details for Web of Science ID 000435539902152

• Terahertz Emission from Hybrid Perovskites Driven by Ultrafast Charge Separation and Strong Electron-Phonon Coupling ADVANCED MATERIALS Guzelturk, B., Belisle, R. A., Smith, M. D., Bruening, K., Prasanna, R., Yuan, Y., Gopalan, V., Tassone, C. J., Karunadasa, H. I., McGehee, M. D., Lindenberg, A. M. 2018; 30 (11)

  Abstract

  Unusual photophysical properties of organic-inorganic hybrid perovskites have not only enabled exceptional performance in optoelectronic devices, but also led to debates on the nature of charge carriers in these materials. This study makes the first observation of intense terahertz (THz) emission from the hybrid perovskite methylammonium lead iodide (CH3 NH3 PbI3 ) following photoexcitation, enabling an ultrafast probe of charge separation, hot-carrier transport, and carrier-lattice coupling under 1-sun-equivalent illumination conditions. Using this approach, the initial charge separation/transport in the hybrid perovskites is shown to be driven by diffusion and not by surface fields or intrinsic ferroelectricity. Diffusivities of the hot and band-edge carriers along the surface normal direction are calculated by analyzing the emitted THz transients, with direct implications for hot-carrier device applications. Furthermore, photogenerated carriers are found to drive coherent terahertz-frequency lattice distortions, associated with reorganizations of the lead-iodide octahedra as well as coupled vibrations of the organic and inorganic sublattices. This strong and coherent carrier-lattice coupling is resolved on femtosecond timescales and found to be important both for resonant and far-above-gap photoexcitation. This study indicates that ultrafast lattice distortions play a key role in the initial processes associated with charge transport.

  View details for PubMedID 29359820

• Anharmonicity of the vibrational modes of phase-change materials: A far-infrared, terahertz, and Raman study VIBRATIONAL SPECTROSCOPY Shportko, K., Zalden, P., Lindenberg, A. M., Rueckamp, R., Grueninger, M. 2018; 95: 51–56

  View details for DOI 10.1016/j.vibspec.2018.01.005

  View details for Web of Science ID 000428832000008

• Ultrafast Electric Field Pulse Control of Giant Temperature Change in Ferroelectrics PHYSICAL REVIEW LETTERS Qi, Y., Liu, S., Lindenberg, A. M., Rappe, A. M. 2018; 120 (5): 055901

  Abstract

  There is a surge of interest in developing environmentally friendly solid-state-based cooling technology. Here, we point out that a fast cooling rate (≈10^{11}  K/s) can be achieved by driving solid crystals to a high-temperature phase with a properly designed electric field pulse. Specifically, we predict that an ultrafast electric field pulse can cause a giant temperature decrease up to 32 K in PbTiO_{3} occurring on few picosecond time scales. We explain the underlying physics of this giant electric field pulse-induced temperature change with the concept of internal energy redistribution: the electric field does work on a ferroelectric crystal and redistributes its internal energy, and the way the kinetic energy is redistributed determines the temperature change and strongly depends on the electric field temporal profile. This concept is supported by our all-atom molecular dynamics simulations of PbTiO_{3} and BaTiO_{3}. Moreover, this internal energy redistribution concept can also be applied to understand electrocaloric effect. We further propose new strategies for inducing giant cooling effect with ultrafast electric field pulse. This Letter offers a general framework to understand electric-field-induced temperature change and highlights the opportunities of electric field engineering for controlled design of fast and efficient cooling technology.

  View details for DOI 10.1103/PhysRevLett.120.055901

  View details for Web of Science ID 000423522800010

  View details for PubMedID 29481168

• Dynamic Optical Tuning of Interlayer Interactions in the Transition Metal Dichalcogenides NANO LETTERS Mannebach, E. M., Nyby, C., Ernst, F., Zhou, Y., Tolsma, J., Li, Y., Sher, M., Tung, I., Zhou, H., Zhang, Q., Seyler, K. L., Clark, G., Lin, Y., Zhu, D., Glownia, J. M., Kozina, M. E., Song, S., Nelson, S., Mehta, A., Yu, Y., Pant, A., Aslan, O., Raja, A., Guo, Y., DiChiara, A., Mao, W., Cao, L., Tongay, S., Sun, J., Singh, D. J., Heinz, T. F., Xu, X., MacDonald, A. H., Reed, E., Wen, H., Lindenberg, A. M. 2017; 17 (12): 7761-7766

  View details for DOI 10.1021/acs.nanolett.7b03955

  View details for Web of Science ID 000418393300081

• Structural imaging of nanoscale phonon transport in ferroelectrics excited by metamaterial-enhanced terahertz fields PHYSICAL REVIEW MATERIALS Zhu, Y., Chen, F., Park, J., Sasikumar, K., Hu, B., Damodaran, A. R., Jung, I., Highland, M. J., Cai, Z., Tung, I., Walko, D. A., Freeland, J. W., Martin, L. W., Sankaranarayanan, S. S., Evans, P. G., Lindenberg, A. M., Wen, H. 2017; 1 (6)

  View details for DOI 10.1103/PhysRevMaterials.1.060601

  View details for Web of Science ID 000416596500001

• Structural origins of broadband emission from layered Pb-Br hybrid perovskites. Chemical science Smith, M. D., Jaffe, A., Dohner, E. R., Lindenberg, A. M., Karunadasa, H. I. 2017; 8 (6): 4497-4504

  Abstract

  Through structural and optical studies of a series of two-dimensional hybrid perovskites, we show that broadband emission upon near-ultraviolet excitation is common to (001) lead-bromide perovskites. Importantly, we find that the relative intensity of the broad emission correlates with increasing out-of-plane distortion of the Pb-(μ-Br)-Pb angle in the inorganic sheets. Temperature- and power-dependent photoluminescence data obtained on a representative (001) perovskite support an intrinsic origin to the broad emission from the bulk material, where photogenerated carriers cause excited-state lattice distortions mediated through electron-lattice coupling. In contrast, most inorganic phosphors contain extrinsic emissive dopants or emissive surface sites. The design rules established here could allow us to systematically optimize white-light emission from layered hybrid perovskites by fine-tuning the bulk crystal structure.

  View details for DOI 10.1039/c7sc01590a

  View details for PubMedID 28970879

  View details for PubMedCentralID PMC5618335

• Bismuth-based double perovskites for non-toxic photovoltaics Slavney, A., Hu, T., Lindenberg, A., Karunadasa, H. AMER CHEMICAL SOC. 2017

  View details for Web of Science ID 000430569102442

• Picosecond light-induced rotational disordering in the hybrid perovskites Lindenberg, A. AMER CHEMICAL SOC. 2017

  View details for Web of Science ID 000430569100140

• Broadband white-light emission in two-dimensional layered lead-bromide perovskites Hu, T., Smith, M., Dohner, E., Sher, M., Wu, X., Trinh, M., Fisher, A., Corbett, J., Zhu, X., Karunadasa, H., Lindenberg, A. AMER CHEMICAL SOC. 2017

  View details for Web of Science ID 000430569103208

• Engineering the Structural and Electronic Phases of MoTe2 through W Substitution NANO LETTERS Rhodes, D., Chenet, D. A., Janicek, B. E., Nyby, C., Lin, Y., Jin, W., Edelberg, D., Mannebach, E., Finney, N., Antony, A., Schiros, T., Klarr, T., Mazzoni, A., Chin, M., Chiu, Y., Zheng, W., Zhang, Q. R., Ernst, F., Dadayp, J. I., Tong, X., Ma, J., Lou, R., Wan, S., Qian, T., Ding, H., Osgood, R. M., Paley, D. W., Lindenberg, A. M., Huang, P. Y., Pasupathy, A. N., Dubey, M., Hone, J., Balicas, L. 2017; 17 (3): 1616-1622

  View details for DOI 10.1021/acs.nanolett.6b04814

  View details for Web of Science ID 000396185800043

• Ultrafast light-induced symmetry changes in single BaTiO3 nanowires JOURNAL OF MATERIALS CHEMISTRY C Kuo, Y., Nah, S., He, K., Hu, T., Lindenberg, A. M. 2017; 5 (6): 1522-1528

  View details for DOI 10.1039/c6tc04448d

  View details for Web of Science ID 000395888900029

• Structural origins of broadband emission from layered Pb–Br hybrid perovskites Chemical Science Smith, M. D., Jaffe, A., Dohner, E. R., Lindenberg, A. M., Karunadasa, H. I. 2017: 4497-4504

  Abstract

  Through structural and optical studies of a series of two-dimensional hybrid perovskites, we show that broadband emission upon near-ultraviolet excitation is common to (001) lead-bromide perovskites. Importantly, we find that the relative intensity of the broad emission correlates with increasing out-of-plane distortion of the Pb-(μ-Br)-Pb angle in the inorganic sheets. Temperature- and power-dependent photoluminescence data obtained on a representative (001) perovskite support an intrinsic origin to the broad emission from the bulk material, where photogenerated carriers cause excited-state lattice distortions mediated through electron-lattice coupling. In contrast, most inorganic phosphors contain extrinsic emissive dopants or emissive surface sites. The design rules established here could allow us to systematically optimize white-light emission from layered hybrid perovskites by fine-tuning the bulk crystal structure.

  View details for DOI 10.1039/C7SC01590A

  View details for PubMedCentralID PMC5618335

• Light-induced picosecond rotational disordering of the inorganic sublattice in hybrid perovskites. Science advances Wu, X. n., Tan, L. Z., Shen, X. n., Hu, T. n., Miyata, K. n., Trinh, M. T., Li, R. n., Coffee, R. n., Liu, S. n., Egger, D. A., Makasyuk, I. n., Zheng, Q. n., Fry, A. n., Robinson, J. S., Smith, M. D., Guzelturk, B. n., Karunadasa, H. I., Wang, X. n., Zhu, X. n., Kronik, L. n., Rappe, A. M., Lindenberg, A. M. 2017; 3 (7): e1602388

  Abstract

  Femtosecond resolution electron scattering techniques are applied to resolve the first atomic-scale steps following absorption of a photon in the prototypical hybrid perovskite methylammonium lead iodide. Following above-gap photoexcitation, we directly resolve the transfer of energy from hot carriers to the lattice by recording changes in the mean square atomic displacements on 10-ps time scales. Measurements of the time-dependent pair distribution function show an unexpected broadening of the iodine-iodine correlation function while preserving the Pb-I distance. This indicates the formation of a rotationally disordered halide octahedral structure developing on picosecond time scales. This work shows the important role of light-induced structural deformations within the inorganic sublattice in elucidating the unique optoelectronic functionality exhibited by hybrid perovskites and provides new understanding of hot carrier-lattice interactions, which fundamentally determine solar cell efficiencies.

  View details for PubMedID 28782016

• Visualization of Atomic-Scale Motions in Materials via Femtosecond X-Ray Scattering Techniques ANNUAL REVIEW OF MATERIALS RESEARCH, VOL 47 Lindenberg, A. M., Johnson, S. L., Reis, D. A., Clarke, D. R. 2017; 47: 425–49

  View details for DOI 10.1146/annurev-matsci-070616-124152

  View details for Web of Science ID 000407726600018

• Dynamic Optical Tuning of Interlayer Interactions in the Transition Metal Dichalcogenides. Nano letters Mannebach, E. M., Nyby, C. n., Ernst, F. n., Zhou, Y. n., Tolsma, J. n., Li, Y. n., Sher, M. J., Tung, I. C., Zhou, H. n., Zhang, Q. n., Seyler, K. L., Clark, G. n., Lin, Y. n., Zhu, D. n., Glownia, J. M., Kozina, M. E., Song, S. n., Nelson, S. n., Mehta, A. n., Yu, Y. n., Pant, A. n., Aslan, O. B., Raja, A. n., Guo, Y. n., DiChiara, A. n., Mao, W. n., Cao, L. n., Tongay, S. n., Sun, J. n., Singh, D. J., Heinz, T. F., Xu, X. n., MacDonald, A. H., Reed, E. n., Wen, H. n., Lindenberg, A. M. 2017; 17 (12): 7761–66

  Abstract

  Modulation of weak interlayer interactions between quasi-two-dimensional atomic planes in the transition metal dichalcogenides (TMDCs) provides avenues for tuning their functional properties. Here we show that above-gap optical excitation in the TMDCs leads to an unexpected large-amplitude, ultrafast compressive force between the two-dimensional layers, as probed by in situ measurements of the atomic layer spacing at femtosecond time resolution. We show that this compressive response arises from a dynamic modulation of the interlayer van der Waals interaction and that this represents the dominant light-induced stress at low excitation densities. A simple analytic model predicts the magnitude and carrier density dependence of the measured strains. This work establishes a new method for dynamic, nonequilibrium tuning of correlation-driven dispersive interactions and of the optomechanical functionality of TMDC quasi-two-dimensional materials.

  View details for PubMedID 29119791

• 2D materials advances: from large scale synthesis and controlled heterostructures to improved characterization techniques, defects and applications 2D MATERIALS Lin, Z., McCreary, A., Briggs, N., Subramanian, S., Zhang, K., Sun, Y., Li, X., Borys, N. J., Yuan, H., Fullerton-Shirey, S. K., Chernikov, A., Zhao, H., McDonnell, S., Lindenberg, A. M., Xiao, K., LeRoy, B. J., Drndic, M., Hwang, J. C., Park, J., Chhowalla, M., Schaak, R. E., Javey, A., Hersam, M. C., Robinson, J., Terrones, M. 2016; 3 (4)

  View details for DOI 10.1088/2053-1583/3/4/042001

  View details for Web of Science ID 000390767600001

• Ultrafast terahertz-field-driven ionic response in ferroelectric BaTiO3 PHYSICAL REVIEW B Chen, F., Zhu, Y., Liu, S., Qi, Y., Hwang, H. Y., Brandt, N. C., Lu, J., QUIRIN, F., Enquist, H., Zalden, P., Hu, T., Goodfellow, J., Sher, M., Hoffmann, M. C., Zhu, D., Lemke, H., Glownia, J., Chollet, M., Damodaran, A. R., Park, J., Cai, Z., Jung, I. W., Highland, M. J., Walko, D. A., Freeland, J. W., Evans, P. G., Vailionis, A., Larsson, J., Nelson, K. A., Rappe, A. M., Sokolowski-Tinten, K., Martin, L. W., Wen, H., Lindenberg, A. M. 2016; 94 (18)

  View details for DOI 10.1103/PhysRevB.94.180104

  View details for Web of Science ID 000388465200001

• Picosecond Electric-Field-Induced Threshold Switching in Phase-Change Materials. Physical review letters Zalden, P., Shu, M. J., Chen, F., Wu, X., Zhu, Y., Wen, H., Johnston, S., Shen, Z., Landreman, P., Brongersma, M., Fong, S. W., Wong, H. P., Sher, M., Jost, P., Kaes, M., Salinga, M., von Hoegen, A., Wuttig, M., Lindenberg, A. M. 2016; 117 (6): 067601-?

  Abstract

  Many chalcogenide glasses undergo a breakdown in electronic resistance above a critical field strength. Known as threshold switching, this mechanism enables field-induced crystallization in emerging phase-change memory. Purely electronic as well as crystal nucleation assisted models have been employed to explain the electronic breakdown. Here, picosecond electric pulses are used to excite amorphous Ag_{4}In_{3}Sb_{67}Te_{26}. Field-dependent reversible changes in conductivity and pulse-driven crystallization are observed. The present results show that threshold switching can take place within the electric pulse on subpicosecond time scales-faster than crystals can nucleate. This supports purely electronic models of threshold switching and reveals potential applications as an ultrafast electronic switch.

  View details for DOI 10.1103/PhysRevLett.117.067601

  View details for PubMedID 27541475

• Transient terahertz photoconductivity measurements of minority-carrier lifetime in tin sulfide thin films: Advanced metrology for an early stage photovoltaic material (vol 119, 035101, 2016) JOURNAL OF APPLIED PHYSICS Jaramillo, R., Sher, M., Ofori-Okai, B. K., Steinmann, V., Yang, C., Hartman, K., Nelson, K. A., Lindenberg, A. M., Gordon, R. G., Buonassisi, T. 2016; 119 (24)

  View details for DOI 10.1063/1.4954931

  View details for Web of Science ID 000379163800063

• Mechanism for Broadband White-Light Emission from Two-Dimensional (110) Hybrid Perovskites JOURNAL OF PHYSICAL CHEMISTRY LETTERS Hu, T., Smith, M. D., Dohner, E. R., Sher, M., Wu, X., Tuan Trinh, M., Fisher, A., Corbett, J., Zhu, X., Karunadasa, H. I., Lindenberg, A. M. 2016; 7 (12): 2258-2263

  Abstract

  The recently discovered phenomenon of broadband white-light emission at room temperature in the (110) two-dimensional organic-inorganic perovskite (N-MEDA)[PbBr4] (N-MEDA = N(1)-methylethane-1,2-diammonium) is promising for applications in solid-state lighting. However, the spectral broadening mechanism and, in particular, the processes and dynamics associated with the emissive species are still unclear. Herein, we apply a suite of ultrafast spectroscopic probes to measure the primary events directly following photoexcitation, which allows us to resolve the evolution of light-induced emissive states associated with white-light emission at femtosecond resolution. Terahertz spectra show fast free carrier trapping and transient absorption spectra show the formation of self-trapped excitons on femtosecond time-scales. Emission-wavelength-dependent dynamics of the self-trapped exciton luminescence are observed, indicative of an energy distribution of photogenerated emissive states in the perovskite. Our results are consistent with photogenerated carriers self-trapped in a deformable lattice due to strong electron-phonon coupling, where permanent lattice defects and correlated self-trapped states lend further inhomogeneity to the excited-state potential energy surface.

  View details for DOI 10.1021/acs.jpclett.6b00793

  View details for Web of Science ID 000378196000017

  View details for PubMedID 27246299

• Time- and Temperature-Independent Local Carrier Mobility and Effects of Regioregularity in Polymer-Fullerene Organic Semiconductors ADVANCED ELECTRONIC MATERIALS Sher, M., Bartelt, J. A., Burke, T. M., Salleo, A., McGehee, M. D., Lindenberg, A. M. 2016; 2 (3)

  View details for DOI 10.1002/aelm.201500351

  View details for Web of Science ID 000372922800013

• A Bismuth-Halide Double Perovskite with Long Carrier Recombination Lifetime for Photovoltaic Applications. Journal of the American Chemical Society Slavney, A. H., Hu, T., Lindenberg, A. M., Karunadasa, H. I. 2016; 138 (7): 2138-2141

  Abstract

  Despite the remarkable rise in efficiencies of solar cells containing the lead-halide perovskite absorbers RPbX3 (R = organic cation; X = Br(-) or I(-)), the toxicity of lead remains a concern for the large-scale implementation of this technology. This has spurred the search for lead-free materials with similar optoelectronic properties. Here, we use the double-perovskite structure to incorporate nontoxic Bi(3+) into the perovskite lattice in Cs2AgBiBr6 (1). The solid shows a long room-temperature fundamental photoluminescence (PL) lifetime of ca. 660 ns, which is very encouraging for photovoltaic applications. Comparison between single-crystal and powder PL decay curves of 1 suggests inherently high defect tolerance. The material has an indirect bandgap of 1.95 eV, suited for a tandem solar cell. Furthermore, 1 is significantly more heat and moisture stable compared to (MA)PbI3. The extremely promising optical and physical properties of 1 shown here motivate further exploration of both inorganic and hybrid halide double perovskites for photovoltaics and other optoelectronics.

  View details for DOI 10.1021/jacs.5b13294

  View details for PubMedID 26853379

• Transient terahertz photoconductivity measurements of minority-carrier lifetime in tin sulfide thin films: Advanced metrology for an early stage photovoltaic material JOURNAL OF APPLIED PHYSICS Jaramillo, R., Sher, M., Ofori-Okai, B. K., Steinmann, V., Yang, C., Hartman, K., Nelson, K. A., Lindenberg, A. M., Gordon, R. G., Buonassisi, T. 2016; 119 (3)

  View details for DOI 10.1063/1.4940157

  View details for Web of Science ID 000369287900019

• The origin of incipient ferroelectricity in lead telluride. Nature communications Jiang, M. P., Trigo, M., Savic, I., Fahy, S., Murray, É. D., Bray, C., Clark, J., Henighan, T., Kozina, M., Chollet, M., Glownia, J. M., Hoffmann, M. C., Zhu, D., Delaire, O., May, A. F., Sales, B. C., Lindenberg, A. M., Zalden, P., Sato, T., Merlin, R., Reis, D. A. 2016; 7: 12291-?

  Abstract

  The interactions between electrons and lattice vibrations are fundamental to materials behaviour. In the case of group IV-VI, V and related materials, these interactions are strong, and the materials exist near electronic and structural phase transitions. The prototypical example is PbTe whose incipient ferroelectric behaviour has been recently associated with large phonon anharmonicity and thermoelectricity. Here we show that it is primarily electron-phonon coupling involving electron states near the band edges that leads to the ferroelectric instability in PbTe. Using a combination of nonequilibrium lattice dynamics measurements and first principles calculations, we find that photoexcitation reduces the Peierls-like electronic instability and reinforces the paraelectric state. This weakens the long-range forces along the cubic direction tied to resonant bonding and low lattice thermal conductivity. Our results demonstrate how free-electron-laser-based ultrafast X-ray scattering can be utilized to shed light on the microscopic mechanisms that determine materials properties.

  View details for DOI 10.1038/ncomms12291

  View details for PubMedID 27447688

  View details for PubMedCentralID PMC4961866

• Ultrafast Terahertz Gating of the Polarization and Giant Nonlinear Optical Response in BiFeO3 Thin Films ADVANCED MATERIALS Chen, F., Goodfellow, J., Liu, S., Grinberg, I., Hoffmann, M. C., Damodaran, A. R., Zhu, Y., Zalden, P., Zhang, X., Takeuchi, I., Rappe, A. M., Martin, L. W., Wen, H., Lindenberg, A. M. 2015; 27 (41): 6371-?

  Abstract

  Terahertz pulses are applied as an all-optical bias to ferroelectric thin-film BiFeO3 while monitoring the time-dependent ferroelectric polarization through its nonlinear optical response. Modulations in the intensity of the second harmonic light generated by the film correspond to on-off ratios of 220× gateable on femtosecond timescales. Polarization modulations comparable to the built-in static polarization are observed.

  View details for DOI 10.1002/adma.201502975

  View details for Web of Science ID 000364343700009

• Ultrafast Terahertz Gating of the Polarization and Giant Nonlinear Optical Response in BiFeO3 Thin Films. Advanced materials (Deerfield Beach, Fla.) Chen, F., Goodfellow, J., Liu, S., Grinberg, I., Hoffmann, M. C., Damodaran, A. R., Zhu, Y., Zalden, P., Zhang, X., Takeuchi, I., Rappe, A. M., Martin, L. W., Wen, H., Lindenberg, A. M. 2015; 27 (41): 6371-5

  Abstract

  Terahertz pulses are applied as an all-optical bias to ferroelectric thin-film BiFeO3 while monitoring the time-dependent ferroelectric polarization through its nonlinear optical response. Modulations in the intensity of the second harmonic light generated by the film correspond to on-off ratios of 220× gateable on femtosecond timescales. Polarization modulations comparable to the built-in static polarization are observed.

  View details for DOI 10.1002/adma.201502975

  View details for PubMedID 26389651

• Dynamic Structural Response and Deformations of Monolayer MoS2 Visualized by Femtosecond Electron Diffraction NANO LETTERS Mannebach, E. M., Li, R., Duerloo, K., Nyby, C., Zalden, P., Vecchione, T., Ernst, F., Reid, A. H., Chase, T., Shen, X., Weathersby, S., Hast, C., Hettel, R., Coffee, R., Hartmann, N., Fry, A. R., Yu, Y., Cao, L., Heinz, T. F., Reed, E. J., Duerr, H. A., Wang, X., Lindenberg, A. M. 2015; 15 (10): 6889-6895

  Abstract

  Two-dimensional materials are subject to intrinsic and dynamic rippling that modulates their optoelectronic and electromechanical properties. Here, we directly visualize the dynamics of these processes within monolayer transition metal dichalcogenide MoS2 using femtosecond electron scattering techniques as a real-time probe with atomic-scale resolution. We show that optical excitation induces large-amplitude in-plane displacements and ultrafast wrinkling of the monolayer on nanometer length-scales, developing on picosecond time-scales. These deformations are associated with several percent peak strains that are fully reversible over tens of millions of cycles. Direct measurements of electron-phonon coupling times and the subsequent interfacial thermal heat flow between the monolayer and substrate are also obtained. These measurements, coupled with first-principles modeling, provide a new understanding of the dynamic structural processes that underlie the functionality of two-dimensional materials and open up new opportunities for ultrafast strain engineering using all-optical methods.

  View details for DOI 10.1021/acs.nanolett.5b02805

  View details for PubMedID 26322659

• How Supercooled Liquid Phase-Change Materials Crystallize: Snapshots after Femtosecond Optical Excitation CHEMISTRY OF MATERIALS Zalden, P., von Hoegen, A., Landreman, P., Wuttig, M., Lindenberg, A. M. 2015; 27 (16): 5641-5646

  View details for DOI 10.1021/acs.chemmater.5b02011

  View details for Web of Science ID 000360323700024

• THz-Pulse-Induced Selective Catalytic CO Oxidation on Ru. Physical review letters Larue, J. L., Katayama, T., Lindenberg, A., Fisher, A. S., Öström, H., Nilsson, A., Ogasawara, H. 2015; 115 (3): 036103-?

  Abstract

  We demonstrate the use of intense, quasi-half-cycle THz pulses, with an associated electric field component comparable to intramolecular electric fields, to direct the reaction coordinate of a chemical reaction by stimulating the nuclear motions of the reactants. Using a strong electric field from a THz pulse generated via coherent transition radiation from an ultrashort electron bunch, we present evidence that CO oxidation on Ru(0001) is selectively induced, while not promoting the thermally induced CO desorption process. The reaction is initiated by the motion of the O atoms on the surface driven by the electric field component of the THz pulse, rather than thermal heating of the surface.

  View details for PubMedID 26230806

• THz-Pulse-Induced Selective Catalytic CO Oxidation on Ru PHYSICAL REVIEW LETTERS Larue, J. L., Katayama, T., Lindenberg, A., Fisher, A. S., Ostrom, H., Nilsson, A., Ogasawara, H. 2015; 115 (3)

  Abstract

  We demonstrate the use of intense, quasi-half-cycle THz pulses, with an associated electric field component comparable to intramolecular electric fields, to direct the reaction coordinate of a chemical reaction by stimulating the nuclear motions of the reactants. Using a strong electric field from a THz pulse generated via coherent transition radiation from an ultrashort electron bunch, we present evidence that CO oxidation on Ru(0001) is selectively induced, while not promoting the thermally induced CO desorption process. The reaction is initiated by the motion of the O atoms on the surface driven by the electric field component of the THz pulse, rather than thermal heating of the surface.

  View details for DOI 10.1103/PhysRevLett.115.036103

  View details for Web of Science ID 000358024500005

• Mega-electron-volt ultrafast electron diffraction at SLAC National Accelerator Laboratory REVIEW OF SCIENTIFIC INSTRUMENTS WEATHERSBY, S. P., Brown, G., Centurion, M., CHASE, T. F., Coffee, R., Corbett, J., Eichner, J. P., Frisch, J. C., Fry, A. R., Guehr, M., Hartmann, N., Hast, C., HETTEL, R., Jobe, R. K., Jongewaard, E. N., LEWANDOWSKI, J. R., Li, R. K., Lindenberg, A. M., Makasyuk, I., May, J. E., McCormick, D., Nguyen, M. N., Reid, A. H., Shen, X., Sokolowski-Tinten, K., Vecchione, T., Vetter, S. L., Wu, J., Yang, J., Duerr, H. A., Wang, X. J. 2015; 86 (7)

  Abstract

  Ultrafast electron probes are powerful tools, complementary to x-ray free-electron lasers, used to study structural dynamics in material, chemical, and biological sciences. High brightness, relativistic electron beams with femtosecond pulse duration can resolve details of the dynamic processes on atomic time and length scales. SLAC National Accelerator Laboratory recently launched the Ultrafast Electron Diffraction (UED) and microscopy Initiative aiming at developing the next generation ultrafast electron scattering instruments. As the first stage of the Initiative, a mega-electron-volt (MeV) UED system has been constructed and commissioned to serve ultrafast science experiments and instrumentation development. The system operates at 120-Hz repetition rate with outstanding performance. In this paper, we report on the SLAC MeV UED system and its performance, including the reciprocal space resolution, temporal resolution, and machine stability.

  View details for DOI 10.1063/1.4926994

  View details for Web of Science ID 000358934400053

  View details for PubMedID 26233391

• Visualization of nanocrystal breathing modes at extreme strains NATURE COMMUNICATIONS Szilagyi, E., Wittenberg, J. S., Miller, T. A., Lutker, K., Quirin, F., Lemke, H., Zhu, D., Chollet, M., Robinson, J., Wen, H., Sokolowski-Tinten, K., Lindenberg, A. M. 2015; 6

  Abstract

  Nanoscale dimensions in materials lead to unique electronic and structural properties with applications ranging from site-specific drug delivery to anodes for lithium-ion batteries. These functional properties often involve large-amplitude strains and structural modifications, and thus require an understanding of the dynamics of these processes. Here we use femtosecond X-ray scattering techniques to visualize, in real time and with atomic-scale resolution, light-induced anisotropic strains in nanocrystal spheres and rods. Strains at the percent level are observed in CdS and CdSe samples, associated with a rapid expansion followed by contraction along the nanosphere or nanorod radial direction driven by a transient carrier-induced stress. These morphological changes occur simultaneously with the first steps in the melting transition on hundreds of femtosecond timescales. This work represents the first direct real-time probe of the dynamics of these large-amplitude strains and shape changes in few-nanometre-scale particles.

  View details for DOI 10.1038/ncomms7577

  View details for Web of Science ID 000352720700012

  View details for PubMedID 25762350

• Color Switching with Enhanced Optical Contrast in Ultrathin Phase-Change Materials and Semiconductors Induced by Femtosecond Laser Pulses ACS PHOTONICS Schlich, F. F., Zalden, P., Lindenberg, A. M., Spolenak, R. 2015; 2 (2): 178-182

  View details for DOI 10.1021/ph500402r

  View details for Web of Science ID 000349814400002

• Ultrafast electronic and structural response of monolayer MoS2 under intense photoexcitation conditions. ACS nano Mannebach, E. M., Duerloo, K. N., Pellouchoud, L. A., Sher, M., Nah, S., Kuo, Y., Yu, Y., Marshall, A. F., Cao, L., Reed, E. J., Lindenberg, A. M. 2014; 8 (10): 10734-10742

  Abstract

  We report on the dynamical response of single layer transition metal dichalcogenide MoS2 to intense above-bandgap photoexcitation using the nonlinear-optical second order susceptibility as a direct probe of the electronic and structural dynamics. Excitation conditions corresponding to the order of one electron-hole pair per unit cell generate unexpected increases in the second harmonic from monolayer films, occurring on few picosecond time-scales. These large amplitude changes recover on tens of picosecond time-scales and are reversible at megahertz repetition rates with no photoinduced change in lattice symmetry observed despite the extreme excitation conditions.

  View details for DOI 10.1021/nn5044542

  View details for PubMedID 25244589

• Room-temperature stabilization of nanoscale superionic Ag2Se NANOTECHNOLOGY Hu, T., Wittenberg, J. S., Lindenberg, A. M. 2014; 25 (41)

  View details for DOI 10.1088/0957-4484/25/41/415705

  View details for Web of Science ID 000342580300016

• Room-temperature stabilization of nanoscale superionic Ag2Se. Nanotechnology Hu, T., Wittenberg, J. S., Lindenberg, A. M. 2014; 25 (41): 415705-?

  Abstract

  Superionic materials are multi-component solids in which one sub-lattice exhibits high ionic conductivity within a fixed crystalline structure. This is typically associated with a structural phase transition occurring significantly above room temperature. Here, through combined temperature-resolved x-ray diffraction and differential scanning calorimetry, we map out the nanoscale size-dependence of the Ag₂Se tetragonal to superionic phase transition temperature and determine the threshold size for room-temperature stabilization of superionic Ag2Se. For the first time, clear experimental evidence for such stabilization of the highly ionic conducting phase at room temperature is obtained in ∼2 nm diameter spheres, which corresponds to a >100 °C suppression of the bulk phase transition temperature. This may enable technological applications of Ag₂Se in devices where high ionic conductivity at room temperature is required.

  View details for DOI 10.1088/0957-4484/25/41/415705

  View details for PubMedID 25249347

• Ultrafast Electronic and Structural Response of Monolayer MoS2 under Intense Photoexcitation Conditions ACS NANO Mannebach, E. M., Duerloo, K. N., Pellouchoud, L. A., Sher, M., Nah, S., Kuo, Y., Yu, Y., Marshall, A. F., Cao, L., Reed, E. J., Lindenberg, A. M. 2014; 8 (10): 10734-10742

  Abstract

  We report on the dynamical response of single layer transition metal dichalcogenide MoS2 to intense above-bandgap photoexcitation using the nonlinear-optical second order susceptibility as a direct probe of the electronic and structural dynamics. Excitation conditions corresponding to the order of one electron-hole pair per unit cell generate unexpected increases in the second harmonic from monolayer films, occurring on few picosecond time-scales. These large amplitude changes recover on tens of picosecond time-scales and are reversible at megahertz repetition rates with no photoinduced change in lattice symmetry observed despite the extreme excitation conditions.

  View details for DOI 10.1021/nn5044542

  View details for Web of Science ID 000343952600110

• Reversible Optical Switching of Infrared Antenna Resonances with Ultrathin Phase-Change Layers Using Femtosecond Laser Pulses ACS PHOTONICS Michel, A. U., Zalden, P., Chigrin, D. N., Wuttig, M., Lindenberg, A. M., Taubner, T. 2014; 1 (9): 833-839

  View details for DOI 10.1021/ph500121d

  View details for Web of Science ID 000342120300012

• Ultrafast polarization response of an optically trapped single ferroelectric nanowire. Nano letters Nah, S., Kuo, Y., Chen, F., Park, J., Sinclair, R., Lindenberg, A. M. 2014; 14 (8): 4322-4327

  Abstract

  One-dimensional potassium niobate nanowires are of interest as building blocks in integrated piezoelectric devices, exhibiting large nonlinear optical and piezoelectric responses. Here we present femtosecond measurements of light-induced polarization dynamics within an optically trapped ferroelectric nanowire, using the second-order nonlinear susceptibility as a real-time structural probe. Large amplitude, reversible modulations of the nonlinear susceptibility are observed within single nanowires at megahertz repetition rates, developing on few-picosecond time-scales, associated with anomalous coupling of light into the nanowire.

  View details for DOI 10.1021/nl5011228

  View details for PubMedID 25051318

• Picosecond carrier recombination dynamics in chalcogen-hyperdoped silicon APPLIED PHYSICS LETTERS Sher, M., Simmons, C. B., Krich, J. J., Akey, A. J., Winkler, M. T., Recht, D., Buonassisi, T., Aziz, M. J., Lindenberg, A. M. 2014; 105 (5)

  View details for DOI 10.1063/1.4892357

  View details for Web of Science ID 000341153000105

• Below gap optical absorption in GaAs driven by intense, single-cycle coherent transition radiation OPTICS EXPRESS Goodfellow, J., Fuchs, M., Daranciang, D., Ghimire, S., Chen, F., Loos, H., Reis, D. A., Fisher, A. S., Lindenberg, A. M. 2014; 22 (14): 17423-17429

  Abstract

  Single-cycle terahertz fields generated by coherent transition radiation from a relativistic electron beam are used to study the high field optical response of single crystal GaAs. Large amplitude changes in the sub-band-gap optical absorption are induced and probed dynamically by measuring the absorption of a broad-band optical beam generated by transition radiation from the same electron bunch, providing an absolutely synchronized pump and probe geometry. This modification of the optical properties is consistent with strong-field-induced electroabsorption. These processes are pertinent to a wide range of nonlinear terahertz-driven light-matter interactions anticipated at accelerator-based sources.

  View details for DOI 10.1364/OE.22.017423

  View details for Web of Science ID 000340674700072

  View details for PubMedID 25090555

• Ultrafast terahertz-induced response of GeSbTe phase-change materials APPLIED PHYSICS LETTERS Shu, M. J., Zalden, P., Chen, F., Weems, B., Chatzakis, I., Xiong, F., Jeyasingh, R., Hoffmann, M. C., Pop, E., Wong, H. P., Wuttig, M., Lindenberg, A. M. 2014; 104 (25)

  View details for DOI 10.1063/1.4884816

  View details for Web of Science ID 000338515900032

• Measurement of transient atomic displacements in thin films with picosecond and femtometer resolution STRUCTURAL DYNAMICS-US Kozina, M., Hu, T., Wittenberg, J. S., Szilagyi, E., Trigo, M., Miller, T. A., Uher, C., Damodaran, A., Martin, L., Mehta, A., Corbett, J., Safranek, J., Reis, D. A., Lindenberg, A. M. 2014; 1 (3)

  View details for DOI 10.1063/1.4875347

  View details for Web of Science ID 000354989200001

• Real-time visualization of nanocrystal solid-solid transformation pathways. Nano letters Wittenberg, J. S., Miller, T. A., Szilagyi, E., Lutker, K., Quirin, F., Lu, W., Lemke, H., Zhu, D., Chollet, M., Robinson, J., Wen, H., Sokolowski-Tinten, K., Alivisatos, A. P., Lindenberg, A. M. 2014; 14 (4): 1995-1999

  Abstract

  Measurement and understanding of the microscopic pathways materials follow as they transform is crucial for the design and synthesis of new metastable phases of matter. Here we employ femtosecond single-shot X-ray diffraction techniques to measure the pathways underlying solid-solid phase transitions in cadmium sulfide nanorods, a model system for a general class of martensitic transformations. Using picosecond rise-time laser-generated shocks to trigger the transformation, we directly observe the transition state dynamics associated with the wurtzite-to-rocksalt structural phase transformation in cadmium sulfide with atomic-scale resolution. A stress-dependent transition path is observed. At high peak stresses, the majority of the sample is converted directly into the rocksalt phase with no evidence of an intermediate prior to rocksalt formation. At lower peak stresses, a transient five-coordinated intermediate structure is observed consistent with previous first principles modeling.

  View details for DOI 10.1021/nl500043c

  View details for PubMedID 24588125

• Fourier-transform inelastic X-ray scattering from time- and momentum-dependent phonon-phonon correlations NATURE PHYSICS Trigo, M., Fuchs, M., Chen, J., Jiang, M. P., Cammarata, M., Fahy, S., Fritz, D. M., Gaffney, K., Ghimire, S., Higginbotham, A., Johnson, S. L., Kozina, M. E., Larsson, J., Lemke, H., Lindenberg, A. M., Ndabashimiye, G., QUIRIN, F., Sokolowski-Tinten, K., Uher, C., Wang, G., Wark, J. S., Zhu, D., Reis, D. A. 2013; 9 (12): 790-794

  View details for DOI 10.1038/NPHYS2788

  View details for Web of Science ID 000327944600017

• High-pressure Raman spectroscopy of phase change materials APPLIED PHYSICS LETTERS Hsieh, W., Zalden, P., Wuttig, M., Lindenberg, A. M., Mao, W. L. 2013; 103 (19)

  View details for DOI 10.1063/1.4829358

  View details for Web of Science ID 000327817000029

• Ultrafast sub-threshold photo-induced response in crystalline and amorphous GeSbTe thin films APPLIED PHYSICS LETTERS Shu, M. J., Chatzakis, I., Kuo, Y., Zalden, P., Lindenberg, A. M. 2013; 102 (20)

  View details for DOI 10.1063/1.4807731

  View details for Web of Science ID 000320619300035

• Intense terahertz pulses from SLAC electron beams using coherent transition radiation. Review of scientific instruments Wu, Z., Fisher, A. S., Goodfellow, J., Fuchs, M., Daranciang, D., Hogan, M., Loos, H., Lindenberg, A. 2013; 84 (2): 022701-?

  Abstract

  SLAC has two electron accelerators, the Linac Coherent Light Source (LCLS) and the Facility for Advanced Accelerator Experimental Tests (FACET), providing high-charge, high-peak-current, femtosecond electron bunches. These characteristics are ideal for generating intense broadband terahertz (THz) pulses via coherent transition radiation. For LCLS and FACET respectively, the THz pulse duration is typically 20 and 80 fs RMS and can be tuned via the electron bunch duration; emission spectra span 3-30 THz and 0.5 THz-5 THz; and the energy in a quasi-half-cycle THz pulse is 0.2 and 0.6 mJ. The peak electric field at a THz focus has reached 4.4 GV/m (0.44 V/Å) at LCLS. This paper presents measurements of the terahertz pulses and preliminary observations of nonlinear materials response.

  View details for DOI 10.1063/1.4790427

  View details for PubMedID 23464183

• Intense terahertz pulses from SLAC electron beams using coherent transition radiation REVIEW OF SCIENTIFIC INSTRUMENTS Wu, Z., Fisher, A. S., Goodfellow, J., Fuchs, M., Daranciang, D., Hogan, M., Loos, H., Lindenberg, A. 2013; 84 (2)

  Abstract

  SLAC has two electron accelerators, the Linac Coherent Light Source (LCLS) and the Facility for Advanced Accelerator Experimental Tests (FACET), providing high-charge, high-peak-current, femtosecond electron bunches. These characteristics are ideal for generating intense broadband terahertz (THz) pulses via coherent transition radiation. For LCLS and FACET respectively, the THz pulse duration is typically 20 and 80 fs RMS and can be tuned via the electron bunch duration; emission spectra span 3-30 THz and 0.5 THz-5 THz; and the energy in a quasi-half-cycle THz pulse is 0.2 and 0.6 mJ. The peak electric field at a THz focus has reached 4.4 GV/m (0.44 V/Å) at LCLS. This paper presents measurements of the terahertz pulses and preliminary observations of nonlinear materials response.

  View details for DOI 10.1063/1.4790427

  View details for Web of Science ID 000316954600003

  View details for PubMedID 23464183

• The mechanism of ultrafast structural switching in superionic copper (I) sulphide nanocrystals NATURE COMMUNICATIONS Miller, T. A., Wittenberg, J. S., Wen, H., Connor, S., Cui, Y., Lindenberg, A. M. 2013; 4

  Abstract

  Superionic materials are multi-component solids with simultaneous characteristics of both a solid and a liquid. Above a critical temperature associated with a structural phase transition, they exhibit liquid-like ionic conductivities and dynamic disorder within a rigid crystalline structure. Broad applications as electrochemical storage materials and resistive switching devices follow from this abrupt change in ionic mobility, but the microscopic pathways and speed limits associated with this switching process are largely unknown. Here we use ultrafast X-ray spectroscopy and scattering techniques to obtain an atomic-level, real-time view of the transition state in copper sulphide nanocrystals. We observe the transformation to occur on a twenty picosecond timescale and show that this is determined by the ionic hopping time.

  View details for DOI 10.1038/ncomms2385

  View details for Web of Science ID 000316614600039

  View details for PubMedID 23340409

• Ultrafast laser-induced melting and ablation studied by time-resolved diffuse X-ray scattering 18th International Conference on Ultrafast Phenomena Nicoul, M., QUIRIN, F., Lindenberg, A. M., Barty, A., Fritz, D. M., Zhu, D., Lemke, H., Chollet, M., Reis, D. A., Chen, J., Ghimire, S., Trigo, M., Fuchs, M., Gaffney, K. J., Larsson, J., Becker, T., Meyer, S., Payer, T., Heringdorf, F. M., von Hoegen, M. H., Jerman, M., Sokolowski-Tinten, K. E D P SCIENCES. 2013

  View details for DOI 10.1051/epjconf/20134104013

  View details for Web of Science ID 000320558600096

• Photon-Counting Detectors for Pump-Probe Science 60th IEEE Nuclear Science Symposium (NSS) / Medical Imaging Conference (MIC) / 20th International Workshop on Room-Temperature Semiconductor X-ray and Gamma-ray Detectors Kenney, C. J., Dragone, A. B., Segal, J. D., Hasi, J., Mehta, A., Reis, D. A., Markovic, B., Caraguilo, P., Carini, G., Herrmann, S. C., Lindenberg, A. M., Haller, G. IEEE. 2013

  View details for Web of Science ID 000347163503065

• Fourier-transform inelastic X-ray scattering from time and momentum dependent phonon-phonon correlations Nat. Phys. Trigo, M., Fuchs, M., Chen, J., Jiang, M., P., Cammarata, M., Fahy, S., Lindenberg, A. M. 2013

  View details for DOI 10.1038/NPHYS2788

• High-pressure Raman spectroscopy of phase change materials Appl. Phys. Lett. Hsieh, W., Zalden, P., Wuttig, M., Lindenberg, A, M., Mao, W., L. 2013; 103: 191108
• Ultrafast Photovoltaic Response in Ferroelectric Nanolayers PHYSICAL REVIEW LETTERS Daranciang, D., Highland, M. J., Wen, H., Young, S. M., Brandt, N. C., Hwang, H. Y., Vattilana, M., Nicoul, M., Quirin, F., Goodfellow, J., Qi, T., Grinberg, I., Fritz, D. M., Cammarata, M., Zhu, D., Lemke, H. T., Walko, D. A., Dufresne, E. M., Li, Y., Larsson, J., Reis, D. A., Sokolowski-Tinten, K., Nelson, K. A., Rappe, A. M., Fuoss, P. H., Stephenson, G. B., Lindenberg, A. M. 2012; 108 (8)

  Abstract

  We show that light drives large-amplitude structural changes in thin films of the prototypical ferroelectric PbTiO3 via direct coupling to its intrinsic photovoltaic response. Using time-resolved x-ray scattering to visualize atomic displacements on femtosecond time scales, photoinduced changes in the unit-cell tetragonality are observed. These are driven by the motion of photogenerated free charges within the ferroelectric and can be simply explained by a model including both shift and screening currents, associated with the displacement of electrons first antiparallel to and then parallel to the ferroelectric polarization direction.

  View details for DOI 10.1103/PhysRevLett.108.087601

  View details for Web of Science ID 000300669600033

  View details for PubMedID 22463572

• Optical Probes of Ultrafast Electron Dynamics in Photoexcited Ferroelectrics Conference on Lasers and Electro-Optics (CLEO) Goodfellow, J., Daranciang, D., Lindenberg, A. IEEE. 2012

  View details for Web of Science ID 000310362402099

• Ultrafast x-ray spectroscopic and scattering studies of nanoscale superionic phase transitions Conference on Lasers and Electro-Optics (CLEO) Miller, T. A., Wittenberg, J., Wen, H., Lindenberg, A. M. IEEE. 2012

  View details for Web of Science ID 000310362402210

• Ultrafast Optical and X-ray Probes of Nanoscale Solid-Liquid Phase Transformations Conference on Lasers and Electro-Optics (CLEO) Wittenberg, J., Miller, T. A., Wen, H., Lindenberg, A. M. IEEE. 2012

  View details for Web of Science ID 000310362403161

• Observations of laser induced magnetization dynamics in Co/Pd multilayers with coherent x-ray scattering APPLIED PHYSICS LETTERS Wu, B., Zhu, D., Acremann, Y., Miller, T. A., Lindenberg, A. M., Hellwig, O., Stoehr, J., Scherz, A. 2011; 99 (25)

  View details for DOI 10.1063/1.3670305

  View details for Web of Science ID 000299031600042

• Single-cycle terahertz pulses with > 0.2 V/angstrom field amplitudes via coherent transition radiation APPLIED PHYSICS LETTERS Daranciang, D., Goodfellow, J., Fuchs, M., Wen, H., Ghimire, S., Reis, D. A., Loos, H., Fisher, A. S., Lindenberg, A. M. 2011; 99 (14)

  View details for DOI 10.1063/1.3646399

  View details for Web of Science ID 000295625100017

• Observation of Transient Structural-Transformation Dynamics in a Cu2S Nanorod SCIENCE Zheng, H., Rivest, J. B., Miller, T. A., Sadtler, B., Lindenberg, A., Toney, M. F., Wang, L., Kisielowski, C., Alivisatos, A. P. 2011; 333 (6039): 206-209

  Abstract

  The study of first-order structural transformations has been of great interest to scientists in many disciplines. Expectations from phase-transition theory are that the system fluctuates between two equilibrium structures near the transition point and that the region of transition broadens in small crystals. We report the direct observation of structural fluctuations within a single nanocrystal using transmission electron microscopy. We observed trajectories of structural transformations in individual nanocrystals with atomic resolution, which reveal details of the fluctuation dynamics, including nucleation, phase propagation, and pinning of structural domains by defects. Such observations provide crucial insight for the understanding of microscopic pathways of phase transitions.

  View details for DOI 10.1126/science.1204713

  View details for Web of Science ID 000292502700045

  View details for PubMedID 21737738

• Generation of > 100 mu J, Broadband THz Transients with > 10 MV/cm Fields via Coherent Transition Radiation at the Linac Coherent Light Source Conference on Lasers and Electro-Optics (CLEO) Daranciang, D., Goodfellow, J., Ghimire, S., Loos, H., Reis, D., Fisher, A. S., Lindenberg, A. M. IEEE. 2011

  View details for Web of Science ID 000295612401212

• High-speed all-optical terahertz polarization switching by a transient plasma phase modulator APPLIED PHYSICS LETTERS Wen, H., Daranciang, D., Lindenberg, A. M. 2010; 96 (16)

  View details for DOI 10.1063/1.3407514

  View details for Web of Science ID 000277020600003

• Ultrafast Conversions of Hydrogen-Bonded Structures in Liquid Water Observed via Femtosecond Soft X-Ray Spectroscopy Huse, N., Wen, H., Cho, H., Kim, T., Schoenlein, R., W., Lindenberg, A., M. 2010
• Spatiotemporally resolved plasma effect on two-color laser pumped terahertz generation Wen, H., Daranciang, D., Lindenberg, A., IEEE IEEE. 2010

  View details for Web of Science ID 000290513600307

• High-intensity THz interactions with materials: New aspects and applications International Symposium on High Power Laser Ablation 2010 Daranciang, D., Wen, H., Lindenberg, A. M. AMER INST PHYSICS. 2010: 17–25

  View details for Web of Science ID 000287183900002

• Light-Induced Modulation of Ferroelectric Polarization Probed Using Time-Resolved X-Ray Scattering Daranciang, D., Wen, H., Highland, M., Perkins, B., Brandt, N., Nelson, K., Lindenberg, A. M. 2010
• Ultrafast conversions between hydrogen bonded structures in liquid water observed by femtosecond x-ray spectroscopy JOURNAL OF CHEMICAL PHYSICS Wen, H., Huse, N., Schoenlein, R. W., Lindenberg, A. M. 2009; 131 (23)

  Abstract

  We present the first femtosecond soft x-ray spectroscopy in liquids, enabling the observation of changes in hydrogen bond structures in water via core-hole excitation. The oxygen K-edge of vibrationally excited water is probed with femtosecond soft x-ray pulses, exploiting the relation between different water structures and distinct x-ray spectral features. After excitation of the intramolecular OH stretching vibration, characteristic x-ray absorption changes monitor the conversion of strongly hydrogen-bonded water structures to more disordered structures with weaker hydrogen-bonding described by a single subpicosecond time constant. The latter describes the thermalization time of vibrational excitations and defines the characteristic maximum rate with which nonequilibrium populations of more strongly hydrogen-bonded water structures convert to less-bonded ones. On short time scales, the relaxation of vibrational excitations leads to a transient high-pressure state and a transient absorption spectrum different from that of statically heated water.

  View details for DOI 10.1063/1.3273204

  View details for Web of Science ID 000273036300029

  View details for PubMedID 20025333

• Coherent Terahertz Polarization Control through Manipulation of Electron Trajectories PHYSICAL REVIEW LETTERS Wen, H., Lindenberg, A. M. 2009; 103 (2)

  Abstract

  The dynamics of ionized electrons in a plasma can be controlled by synthetic optical fields composed of the fundamental and the second harmonic of femtosecond optical pulses with an arbitrary phase and polarization. We show here that the plasma-emitted half-cycle THz radiation directly reflects the two-dimensional trajectories of the electrons through polarization sensitive THz emission spectroscopy. As a result, we find that the THz polarization smoothly rotates through 2pi radians as the relative phase between the two pulses is adjusted, providing a new means of coherently controlling the polarization of light at THz frequencies.

  View details for DOI 10.1103/PhysRevLett.103.023902

  View details for Web of Science ID 000267887800020

  View details for PubMedID 19659205

• Probing the hydrogen-bond network of water via time-resolved soft X-ray spectroscopy PHYSICAL CHEMISTRY CHEMICAL PHYSICS Huse, N., Wen, H., Nordlund, D., Szilagyi, E., Daranciang, D., Miller, T. A., Nilsson, A., Schoenlein, R. W., Lindenberg, A. M. 2009; 11 (20): 3951-3957

  Abstract

  We report time-resolved studies of hydrogen bonding in liquid H(2)O, in response to direct excitation of the O-H stretch mode at 3 mum, probed via soft X-ray absorption spectroscopy at the oxygen K-edge. This approach employs a newly developed nanofluidic cell for transient soft X-ray spectroscopy in the liquid phase. Distinct changes in the near-edge spectral region (XANES) are observed, and are indicative of a transient temperature rise of 10 K following transient laser excitation and rapid thermalization of vibrational energy. The rapid heating occurs at constant volume and the associated increase in internal pressure, estimated to be 8 MPa, is manifested by distinct spectral changes that differ from those induced by temperature alone. We conclude that the near-edge spectral shape of the oxygen K-edge is a sensitive probe of internal pressure, opening new possibilities for testing the validity of water models and providing new insight into the nature of hydrogen bonding in water.

  View details for DOI 10.1039/b822210j

  View details for Web of Science ID 000266065400018

  View details for PubMedID 19440624

• Ultrafast Electron Cascades Driven by Intense Femtosecond THz Pulses 16th International Conference on Ultrafast Phenomena Wen, H., Wiczer, M., Lindenberg, A. SPRINGER-VERLAG BERLIN. 2009: 654–656

  View details for Web of Science ID 000282108000212

• Coherent Control of the Polarization of Ultrafast Terahertz Pulses Conference on Lasers and Electro-Optics/Quantum Electronics and Laser Science Conference (CLEO/QELS 2009) Wen, H., Lindenberg, A. IEEE. 2009: 640–641

  View details for Web of Science ID 000274751300322

• Ultrafast electron cascades in semiconductors driven by intense femtosecond terahertz pulses PHYSICAL REVIEW B Wen, H., Wiczer, M., Lindenberg, A. M. 2008; 78 (12)

  View details for DOI 10.1103/PhysRevB.78.125203

  View details for Web of Science ID 000259691500036

• X-ray diffuse scattering measurements of nucleation dynamics at femtosecond resolution PHYSICAL REVIEW LETTERS Lindenberg, A. M., Engemann, S., Gaffney, K. J., Sokolowski-Tinten, K., Larsson, J., Hillyard, P. B., Reis, D. A., Fritz, D. M., ARTHUR, J., Akre, R. A., George, M. J., Deb, A., Bucksbaum, P. H., Hajdu, J., Meyer, D. A., Nicoul, M., Blome, C., Tschentscher, T., Cavalieri, A. L., Falcone, R. W., Lee, S. H., Pahl, R., Rudati, J., Fuoss, P. H., Nelson, A. J., Krejcik, P., Siddons, D. P., Lorazo, P., Hastings, J. B. 2008; 100 (13)

  Abstract

  Femtosecond time-resolved small and wide angle x-ray diffuse scattering techniques are applied to investigate the ultrafast nucleation processes that occur during the ablation process in semiconducting materials. Following intense optical excitation, a transient liquid state of high compressibility characterized by large-amplitude density fluctuations is observed and the buildup of these fluctuations is measured in real time. Small-angle scattering measurements reveal snapshots of the spontaneous nucleation of nanoscale voids within a metastable liquid and support theoretical predictions of the ablation process.

  View details for DOI 10.1103/PhysRevLett.100.135502

  View details for Web of Science ID 000254670300046

  View details for PubMedID 18517965

• Formation of secondary electron cascades in single-crystalline plasma-deposited diamond upon exposure to femtosecond x-ray pulses JOURNAL OF APPLIED PHYSICS Gabrysch, M., Marklund, E., Hajdu, J., Twitchen, D. J., Rudati, J., Lindenberg, A. M., Caleman, C., Falcone, R. W., Tschentscher, T., Moffat, K., Bucksbaum, P. H., Als-Nielsen, J., Nelson, A. J., Siddons, D. P., EMMA, P. J., Krejcik, P., Schlarb, H., ARTHUR, J., Brennan, S., Hastings, J., Isberg, J. 2008; 103 (6)

  View details for DOI 10.1063/1.2890158

  View details for Web of Science ID 000254536900143

• Femtosecond x-ray diffuse scattering measurements of semiconductor ablation dynamics Conference on High-Power Laser Ablation VII Lindenberg, A. M., Engemann, S., Gaffney, K. J., Sokolowski-Tinten, K., Larsson, J., Reis, D., Lorazo, P., Hastings, J. B. SPIE-INT SOC OPTICAL ENGINEERING. 2008

  View details for DOI 10.1117/12.784094

  View details for Web of Science ID 000258905800002

• Measurement of high-field THz-induced photocurrents in semiconductors Journal of Undergraduate Research Wiczer, M., Lindenberg, A., M. 2008; 8
• Nonlinear THz-pump/THz-probe measurements of semiconductor carrier dynamics Conference on Lasers and Electro-Optics/Quantum Electronics and Laser Science Conference (CLEO/QELS 2008) Lindenberg, A. M., Wen, H., Szilagyi, E. IEEE. 2008: 322–323

  View details for Web of Science ID 000260498400162

• Large acoustic transients induced by nonthermal melting of InSb PHYSICAL REVIEW LETTERS Enquist, H., Navirian, H., Hansen, T. N., Lindenberg, A. M., Sondhauss, P., Synnergren, O., Wark, J. S., Larsson, J. 2007; 98 (22)

  Abstract

  We have observed large-amplitude strain waves following a rapid change in density of InSb due to nonthermal melting. The strain has been measured in real time via time-resolved x-ray diffraction, with a temporal resolution better than 2 ps. The change from the solid to liquid density of the surface layer launches a high-amplitude strain wave into the crystalline material below. This induces an effective plane rotation in the asymmetrically cut crystal leading to deflection of the diffracted beam. The uniform strain in the layer below the molten layer is 2.0(+/-0.2)%. A strain of this magnitude develops within 5 ps of the incident pulse showing that the liquid has reached the equilibrium density within this time frame. Both the strain amplitude and the depth of the strained material in the solid can be explained by assuming a reduction in the speed of sound in the nonequilibrium liquid compared to measured equilibrium values.

  View details for DOI 10.1103/PhysRevLett.98.225502

  View details for Web of Science ID 000246910100037

  View details for PubMedID 17677856

• Carrier-density-dependent lattice stability in InSb PHYSICAL REVIEW LETTERS Hillyard, P. B., Gaffney, K. J., Lindenberg, A. M., Engemann, S., Akre, R. A., ARTHUR, J., Blome, C., Bucksbaum, P. H., Cavalieri, A. L., Deb, A., Falcone, R. W., Fritz, D. M., Fuoss, P. H., Hajdu, J., Krejcik, P., Larsson, J., Lee, S. H., Meyer, D. A., Nelson, A. J., Pahl, R., Reis, D. A., Rudati, J., Siddons, D. P., Sokolowski-Tinten, K., von der Linde, D., Hastings, J. B. 2007; 98 (12)

  Abstract

  The ultrafast decay of the x-ray diffraction intensity following laser excitation of an InSb crystal has been utilized to observe carrier dependent changes in the potential energy surface. For the first time, an abrupt carrier dependent onset for potential energy surface softening and the appearance of accelerated atomic disordering for a very high average carrier density have been observed. Inertial dynamics dominate the early stages of crystal disordering for a wide range of carrier densities between the onset of crystal softening and the appearance of accelerated atomic disordering.

  View details for DOI 10.1103/PhysRevLett.98.125501

  View details for PubMedID 17501133

• Ultrafast bond softening in bismuth: Mapping a solid's interatomic potential with X-rays SCIENCE Fritz, D. M., Reis, D. A., Adams, B., Akre, R. A., ARTHUR, J., Blome, C., Bucksbaum, P. H., Cavalieri, A. L., Engemann, S., Fahy, S., Falcone, R. W., Fuoss, P. H., Gaffney, K. J., George, M. J., Hajdu, J., Hertlein, M. P., Hillyard, P. B., Hoegen, M. H., Kammler, M., Kaspar, J., Kienberger, R., Krejcik, P., Lee, S. H., Lindenberg, A. M., McFarland, B., Meyer, D., Montagne, T., Murray, E. D., Nelson, A. J., Nicoul, M., Pahl, R., Rudati, J., Schlarb, H., Siddons, D. P., Sokolowski-Tinten, K., Tschentscher, T., von der Linde, D., Hastings, J. B. 2007; 315 (5812): 633-636

  Abstract

  Intense femtosecond laser excitation can produce transient states of matter that would otherwise be inaccessible to laboratory investigation. At high excitation densities, the interatomic forces that bind solids and determine many of their properties can be substantially altered. Here, we present the detailed mapping of the carrier density-dependent interatomic potential of bismuth approaching a solid-solid phase transition. Our experiments combine stroboscopic techniques that use a high-brightness linear electron accelerator-based x-ray source with pulse-by-pulse timing reconstruction for femtosecond resolution, allowing quantitative characterization of the interatomic potential energy surface of the highly excited solid.

  View details for DOI 10.1126/science.1135009

  View details for Web of Science ID 000243909400039

  View details for PubMedID 17272718

• Ultrafast X-ray scattering in solids LIGHT SCATTERING IN SOLIDS IX Reis, D. A., Lindenberg, A. M. 2007; 108: 371-422

  View details for Web of Science ID 000243862500006

• Carrier dependent stability of a semiconductor lattice measured with femtosecond X-ray diffraction 15th International Conference on Ultrafast Phenomena Gaffney, K. J., Hillyard, P. B., Lindenberg, A. M., Engemann, S., Deb, A., Meyer, D. A. SPRINGER-VERLAG BERLIN. 2007: 710–712

  View details for Web of Science ID 000250104700227

• Ultrafast optical and x-ray measurements of femtosecond lattice dynamics in photoexcited Bismuth Fritz, D, M., Adams, B., Blome, C., Bucksbaum, P., H., Cavalieri, A., L., Engamann et al., S. edited by Corkum, P., Weiner, A., M., Miller, R., J. 2006
• Observation of structural anisotropy and the onset of liquidlike motion during the nonthermal melting of InSb PHYSICAL REVIEW LETTERS Gaffney, K. J., Lindenberg, A. M., Larsson, J., Sokolowski-Tinten, K., Blome, C., Synnergren, O., Sheppard, J., Caleman, C., MacPhee, A. G., Weinstein, D., Lowney, D. P., Allison, T., Matthews, T., Falcone, R. W., Cavalieri, A. L., Fritz, D. M., Lee, S. H., Bucksbaum, P. H., Reis, D. A., Rudati, J., Macrander, A. T., Fuoss, P. H., Kao, C. C., Siddons, D. P., Pahl, R., Moffat, K., Als-Nielsen, J., Duesterer, S., Ischebeck, R., Schlarb, H., Schulte-Schrepping, H., Schneider, J., von der Linde, D., Hignette, O., Sette, F., Chapman, H. N., Lee, R. W., Hansen, T. N., Wark, J. S., Bergh, M., Huldt, G., van der Spoel, D., Timneanu, N., Hajdu, J., Akre, R. A., Bong, E., Krejcik, P., ARTHUR, J., Brennan, S., Luening, K., Hastings, J. B. 2005; 95 (12)

  Abstract

  The melting dynamics of laser excited InSb have been studied with femtosecond x-ray diffraction. These measurements observe the delayed onset of diffusive atomic motion, signaling the appearance of liquidlike dynamics. They also demonstrate that the root-mean-squared displacement in the [111] direction increases faster than in the [110] direction after the first 500 fs. This structural anisotropy indicates that the initially generated fluid differs significantly from the equilibrium liquid.

  View details for DOI 10.1103/PhysRevLett.95.125701

  View details for Web of Science ID 000231908200033

  View details for PubMedID 16197085

• Time-resolved measurements of the structure of water at constant density JOURNAL OF CHEMICAL PHYSICS Lindenberg, A. M., Acremann, Y., Lowney, D. P., Heimann, P. A., Allison, T. K., Matthews, T., Falcone, R. W. 2005; 122 (20)

  Abstract

  Dynamical changes in the structure factor of liquid water, S(Q,t), are measured using time-resolved x-ray diffraction techniques with 100 ps resolution. On short time scales following femtosecond optical excitation, we observe temperature-induced changes associated with rearrangements of the hydrogen-bonded structure at constant volume, before the system has had time to expand. We invert this data to extract transient changes in the pair correlation function associated with isochoric heating effects, and interpret these in terms of a decrease in the local tetrahedral ordering.

  View details for DOI 10.1063/1.1906212

  View details for Web of Science ID 000229544500046

  View details for PubMedID 15945752

• Atomic-scale visualization of inertial dynamics SCIENCE Lindenberg, A. M., Larsson, J., Sokolowski-Tinten, K., Gaffney, K. J., Blome, C., Synnergren, O., Sheppard, J., Caleman, C., MacPhee, A. G., Weinstein, D., Lowney, D. P., Allison, T. K., Matthews, T., Falcone, R. W., Cavalieri, A. L., Fritz, D. M., Lee, S. H., Bucksbaum, P. H., Reis, D. A., Rudati, J., Fuoss, P. H., Kao, C. C., Siddons, D. P., Pahl, R., Als-Nielsen, J., Duesterer, S., Ischebeck, R., Schlarb, H., Schulte-Schrepping, H., Tschentscher, T., Schneider, J., von der Linde, D., Hignette, O., Sette, F., Chapman, H. N., Lee, R. W., Hansen, T. N., Techert, S., Wark, J. S., Bergh, M., Huldt, G., van der Spoel, D., Timneanu, N., Hajdu, J., Akre, R. A., Bong, E., Krejcik, P., ARTHUR, J., Brennan, S., Luening, K., Hastings, J. B. 2005; 308 (5720): 392-395

  Abstract

  The motion of atoms on interatomic potential energy surfaces is fundamental to the dynamics of liquids and solids. An accelerator-based source of femtosecond x-ray pulses allowed us to follow directly atomic displacements on an optically modified energy landscape, leading eventually to the transition from crystalline solid to disordered liquid. We show that, to first order in time, the dynamics are inertial, and we place constraints on the shape and curvature of the transition-state potential energy surface. Our measurements point toward analogies between this nonequilibrium phase transition and the short-time dynamics intrinsic to equilibrium liquids.

  View details for DOI 10.1126/science.1107996

  View details for Web of Science ID 000228492000046

  View details for PubMedID 15831753

• Clocking femtosecond x rays PHYSICAL REVIEW LETTERS Cavalieri, A. L., Fritz, D. M., Lee, S. H., Bucksbaum, P. H., Reis, D. A., Rudati, J., Mills, D. M., Fuoss, P. H., Stephenson, G. B., Kao, C. C., Siddons, D. P., Lowney, D. P., MacPhee, A. G., Weinstein, D., Falcone, R. W., Pahl, R., Als-Nielsen, J., Blome, C., Dusterer, S., Ischebeck, R., Schlarb, H., Schulte-Schrepping, H., Tschentscher, T., Schneider, J., Hignette, O., Sette, F., Sokolowski-Tinten, K., Chapman, H. N., Lee, R. W., Hansen, T. N., Synnergren, O., Larsson, J., Techert, S., Sheppard, J., Wark, J. S., Bergh, M., Caleman, C., Huldt, G., van der Spoel, D., Timneanu, N., Hajdu, J., Akre, R. A., Bong, E., Emma, P., Krejcik, P., ARTHUR, J., Brennan, S., Gaffney, K. J., Lindenberg, A. M., Luening, K., Hastings, J. B. 2005; 94 (11)

  Abstract

  Linear-accelerator-based sources will revolutionize ultrafast x-ray science due to their unprecedented brightness and short pulse duration. However, time-resolved studies at the resolution of the x-ray pulse duration are hampered by the inability to precisely synchronize an external laser to the accelerator. At the Sub-Picosecond Pulse Source at the Stanford Linear-Accelerator Center we solved this problem by measuring the arrival time of each high energy electron bunch with electro-optic sampling. This measurement indirectly determined the arrival time of each x-ray pulse relative to an external pump laser pulse with a time resolution of better than 60 fs rms.

  View details for DOI 10.1103/PhysRevLett.94.114801

  View details for Web of Science ID 000227923200034

  View details for PubMedID 15903864

• Bonding in liquid carbon studied by time-resolved x-ray absorption spectroscopy PHYSICAL REVIEW LETTERS Johnson, S. L., Heimann, P. A., MacPhee, A. G., Lindenberg, A. M., Monteiro, O. R., Chang, Z., Lee, R. W., Falcone, R. W. 2005; 94 (5)

  Abstract

  Even the most basic properties of liquid carbon have long been debated due to the challenge of studying the material at the required high temperature and pressure. Liquid carbon is volatile and thus inherently transient in an unconstrained environment. In this paper we use a new technique of picosecond time-resolved x-ray absorption spectroscopy to study the bonding of liquid carbon at densities near that of the solid. As the density of the liquid increases, we see a change from predominantly sp-bonded atomic sites to a mixture of sp, sp2, and sp3 sites and compare these observations with molecular dynamics simulations.

  View details for DOI 10.1103/PhysRevLett.94.057407

  View details for Web of Science ID 000226941500085

  View details for PubMedID 15783698

• Opportunities and challenges using short-pulse X-ray sources. 2nd International Conference on Photo-Induced Phase Transitions Larsson, J., Synnergren, O., Hansen, T. N., Sokolowski-Tinten, K., Werin, S., Caleman, C., Hajdu, J., Shepherd, J., Wark, J. S., Lindenberg, A. M., Gaffney, K. J., Hastings, J. B. IOP PUBLISHING LTD. 2005: 87–94

  View details for DOI 10.1088/1742-6596/21/1/014

  View details for Web of Science ID 000233012100014

• Bonding in liquid Carbon studied by time-resolved x-ray absorption spectroscopy Phys. Rev. Lett. Johnson, S., L., Heimann, P., A., MacPhee, A., G., Lindenberg, A., M., Monteiro, O., R., Chang et al., Z. 2005; 94: 57407
• Time-resolved X-ray diffraction study of the ferroelectric phase-transition in DKDP CHEMICAL PHYSICS Larsson, J., Sondhauss, P., Synnergren, O., Harbst, M., Heimann, P. A., Lindenberg, A. M., Wark, J. S. 2004; 299 (2-3): 157-161

  View details for DOI 10.1016/j.chemphys.2003.11.019

  View details for Web of Science ID 000220525200002

• A setup for ultrafast time-resolved x-ray absorption spectroscopy Rev. Sci. Instr. Saes, M., Bressler, C., Mourik, F., van, Gawelda, W., Kaiser, M., Chergui et al., M. 2004; 75: 24
• A setup for ultrafast time-resolved x-ray absorption spectroscopy REVIEW OF SCIENTIFIC INSTRUMENTS Saes, M., Bressler, C., van Mourik, F., Gawelda, W., Kaiser, M., Chergui, M., Bressler, C., Grolimund, D., Abela, R., Glover, T. E., Heimann, P. A., Schoenlein, R. W., Johnson, S. L., Lindenberg, A. M., Falcone, R. W. 2004; 75 (1): 24-30

  View details for DOI 10.1063/1.1633003

  View details for Web of Science ID 000187536500003

• Time-resolved x-ray diffraction study of the ferroelectric phase transition in DKDP Chem. Phys. Larsson, J., Sondhauss, P., Synnergren, O., Harbst, M., Heimann, P., A., Lindenberg et al., A., M. 2004; 299: 157
• Transient strain driven by a dense electron-hole plasma PHYSICAL REVIEW LETTERS DeCamp, M. F., Reis, D. A., Cavalieri, A., Bucksbaum, P. H., Clarke, R., Merlin, R., Dufresne, E. M., Arms, D. A., Lindenberg, A. M., MacPhee, A. G., Chang, Z., Lings, B., Wark, J. S., Fahy, S. 2003; 91 (16)

  Abstract

  We measure transient strain in ultrafast laser-excited Ge by time-resolved x-ray anomalous transmission. The development of the coherent strain pulse is dominated by rapid ambipolar diffusion. This pulse extends considerably longer than the laser penetration depth because the plasma initially propagates faster than the acoustic modes. X-ray diffraction simulations are in agreement with the observed dynamics.

  View details for DOI 10.1103/PhysRevLett.91.165502

  View details for Web of Science ID 000186068300026

  View details for PubMedID 14611411

• Properties of liquid silicon observed by time-resolved x-ray absorption spectroscopy PHYSICAL REVIEW LETTERS Johnson, S. L., Heimann, P. A., Lindenberg, A. M., Jeschke, H. O., Garcia, M. E., Chang, Z., Lee, R. W., Rehr, J. J., Falcone, R. W. 2003; 91 (15)

  Abstract

  Time-resolved x-ray spectroscopy at the Si L edges is used to probe the electronic structure of an amorphous Si foil as it melts following absorption of an ultrafast laser pulse. Picosecond temporal resolution allows observation of the transient liquid phase before vaporization and before the liquid breaks up into droplets. The melting causes changes in the spectrum that match predictions of molecular dynamics and ab initio x-ray absorption codes.

  View details for DOI 10.1103/PhysRevLett.91.157403

  View details for Web of Science ID 000185862500045

  View details for PubMedID 14611494

• Properties of liquid Silicon observed by time-resolved x-ray absorption spectroscopy Phys. Rev. Lett. Johnson, S., L., Heimann, P., A., Lindenberg, A., M., Heschke, H., O., Garcia, M., E., Chang, Z. 2003; 91: 157403
• Properties of liquid silicon and carbon studied by ultrafast time-resolved x-ray absorption spectroscopy 13th International Conference on Ultrafast Phenomena Johnson, S. L., Heimann, P. A., Lindenberg, A. M., MacPhee, A. G., Falcone, R. W., Jeschke, H. O., Garcia, M., Rehr, J. J., Lee, R. W., Chang, Z. SPRINGER-VERLAG BERLIN. 2003: 39–41

  View details for Web of Science ID 000182432900011

• Transient strain driven by a dense, electron-hole plasma Phys. Rev. Lett. Lindenberg, A., M., DeCamp, M., F., Reis, D., A., Cavalieri, A., Bucksbaum, P., H., Clarke, R. 2003; 91: 165502
• Picosecond X-ray diffraction studies of laser-excited acoustic phonons in InSb APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING Larsson, J., Allen, A., Bucksbaum, P. H., Falcone, R. W., Lindenberg, A., Naylor, G., Missalla, T., Reis, D. A., Scheidt, K., Sjogren, A., Sondhauss, P., WULFF, M., Wark, J. S. 2002; 75 (4): 467-478

  View details for DOI 10.1007/s003390201421

  View details for Web of Science ID 000176768300002

• Coherent control of phonons probed by time-resolved x-ray diffraction OPTICS LETTERS Lindenberg, A. M., Kang, I., Johnson, S. L., Falcone, R. W., Heimann, P. A., Chang, Z., Lee, R. W., Wark, J. S. 2002; 27 (10): 869-871

  Abstract

  Time-resolved x-ray diffraction with picosecond temporal resolution is used to probe the product state of a coherent control experiment in which a single acoustic mode in a bulk semiconductor is driven to large amplitude or canceled out. It is demonstrated that by shaping ultrafast acoustic pulses one can coherently control the x-ray diffraction efficiency of a crystal on the time scale of a vibrational period, with application to coherent switching of x-ray beams.

  View details for Web of Science ID 000175786100025

  View details for PubMedID 18007955

• Coherent control of phonons probed by picosecond time-resolved x-ray diffraction Opt. Lett. Lindenberg, A., M., Kang, I., Johnson, S., L., Falcone, R., W., Heimann, P., A., Chang, Z. 2002; 27: 869
• Ultrafast X-ray diffraction of laser-irradiated crystals 7th International Conference on Synchrotron Radiation Instrumentation (SRI 2000) Heimann, P. A., Lindenberg, A. M., Kang, I., JOHNSON, S., Missalla, T., Chang, Z., Falcone, R. W., Schoenlein, R. W., Glover, T. E., Padmore, H. A. ELSEVIER SCIENCE BV. 2001: 986–989

  View details for Web of Science ID 000171012800037

• Ultrafast x-ray diffraction of laser-irradiated crystals Nucl. Inst. Meth. A Heimann, P., A., Lindenberg, A., M., Kang, I., Johnson, S., L., Missalla, T., Heimann, P., A. 2001: 467-468,986-989
• Femtosecond X-ray diffraction: Experiments and limits Conference on X-Ray FEL Optics and Instrumentation Wark, J. S., Allen, A. M., Ansbro, P. C., Bucksbaum, P. H., Chang, Z., DeCamp, M., Falcone, R. W., Heimann, P. A., Johnson, S. L., Kang, I., Kapteyn, H. C., Larsson, J., Lee, R. W., Lindenberg, A. M., Merlin, R., Missalla, T., Naylor, G., Padmore, H. A., Reis, D. A., Scheidt, K., Sjoegren, A., Sondhauss, P. C., WULFF, M. SPIE-INT SOCIETY OPTICAL ENGINEERING. 2001: 26–37

  View details for Web of Science ID 000168537600005

• Time-resolved x-ray measurements of polaron dynamics of charge-ordered Nd1/2Sr1/2MnO3 12th International Conference on Ultrafast Phenomena Kang, I., JOHNSON, S., Lindenberg, A., Falcone, R., Missalla, T., Heimann, P., Kim, K. H., Katsufuji, T., Cheong, S. W. SPRINGER-VERLAG BERLIN. 2001: 287–289

  View details for Web of Science ID 000167460300083

• Femtosecond x-ray diffraction: experiments and limits Wark, J., S., Allen, A., M., Ansbro et al., P., C. 2001
• Time-resolved X-ray diffraction from coherent phonons during a laser-induced phase transition PHYSICAL REVIEW LETTERS Lindenberg, A. M., Kang, I., Johnson, S. L., Missalla, T., Heimann, P. A., Chang, Z., Larsson, J., Bucksbaum, P. H., Kapteyn, H. C., Padmore, H. A., Lee, R. W., Wark, J. S., Falcone, R. W. 2000; 84 (1): 111-114

  View details for Web of Science ID 000084587900028

• Time-resolved x-ray diffraction from coherent phonons during a laser-induced phase transition Phys. Rev. Lett. Lindenberg, A., M., Kang, I., Johnson, S., L., Missalla, T., Heimann, P., A., Chang et al., Z. 2000; 84: 111
• Time-resolved x-ray photoabsorption and diffraction on timescales from ns to fs 11th US National Conference on Synchrotron Radiation Instrumentation Heimann, P. A., Missalla, T., Lindenberg, A., Kang, I., JOHNSON, S., Chang, Z., Kapteyn, H. C., Lee, R. W., Falcone, R. W., Schoenlein, R. W., Glover, T. E., Zholents, A. A., Zolotorev, M. S., Padmore, H. A. AMER INST PHYSICS. 2000: 156–160

  View details for Web of Science ID 000088762600029

• Time-resolved x-ray photoabsorption and diffraction on timescales from ns to fs 18th International Conference on X-ray and Inner-Shell Processes Heimann, P. A., Missalla, T., Lindenberg, A., Kang, I., JOHNSON, S., Chang, Z., Kapteyn, H. C., Lee, R. W., Falcone, R. W., Schoenlein, R. W., Glover, T. E., Zholents, A. A., Zolotorev, M. S., Padmore, H. A. AMER INST PHYSICS. 2000: 664–668

  View details for Web of Science ID 000086079900052

• Ultrafast Lattice Dynamics Nonlinear Optics, Quantum Optics, and Ultrafast Phenomena with X-rays Lindenberg, A., M. edited by Adams, B., W. Kluwer. 2000
• Ultrafast structural changes measured by time-resolved X-ray diffraction APPLIED PHYSICS A-MATERIALS SCIENCE & PROCESSING Larsson, J., Heimann, P. A., Lindenberg, A. M., Schuck, P. J., Bucksbaum, P. H., Lee, R. W., Padmore, H. A., Wark, J. S., Falcone, R. W. 1998; 66 (6): 587-591

  View details for Web of Science ID 000073953200001

• Ultrafast structural changes measured by time-resolved x-ray diffraction Appl. Phys. A Larsson, J., Heimann, P., A., Lindenberg, A., M., Schuck, P., J., Bucksbaum, P., H., Lee, R., W. 1998; 66: 587
• Ultra-fast time-resolved x-ray diffraction detected by an averaging mode streak camera 7th Optical-Society-of-America Conference on Applications of High Fields and Short Wavelength Sources Larsson, J., Chang, Z. H., Judd, E., Heimann, P. A., Lindenberg, A. M., Kapteyn, H. C., Murnane, M. M., Lee, R. W., Machachek, A., Wark, J. S., Padmore, H. A., Falcone, R. W. PLENUM PRESS DIV PLENUM PUBLISHING CORP. 1998: 267–270

  View details for Web of Science ID 000076265900042

• Melting of a semiconductor crystal (InSb) with a short laser pulse (100 fs) 4th High Heat Flux Engineering Conference, as part of the SPIE International Symposium on Optical Science, Engineering, and Instrumentation Heimann, P. A., Larsson, J., Lindenberg, A., Schuck, P. J., Judd, E., Bucksbaum, P. H., Lee, R. W., Padmore, H. A., Wark, J. S., Falcone, R. W. SPIE - INT SOC OPTICAL ENGINEERING. 1997: 102–106

  View details for Web of Science ID 000071550400009