Bio


Our research focuses on the study of materials with unconventional magnetic & electronic ground states & phase transitions. Emphasis on design and discovery of new materials. Interests include superconductivity, instabilities of quasi low-dimensional materials and quantum magnetism.

Academic Appointments


Administrative Appointments


  • Director, Geballe Laboratory for Advanced Materials (2013 - Present)
  • Deputy Director, Geballe Laboratory for Advanced Materials (2008 - 2013)

2015-16 Courses


Stanford Advisees


All Publications


  • NMR Evidence for Inhomogeneous Nematic Fluctuations in BaFe2 (As1-xPx)(2) PHYSICAL REVIEW LETTERS Dioguardi, A. P., Kissikov, T., Lin, C. H., Shirer, K. R., Lawson, M. M., Grafe, H., Chu, J., Fisher, I. R., Fernandes, R. M., Curro, N. J. 2016; 116 (10)

    Abstract

    We present evidence for nuclear spin-lattice relaxation driven by glassy nematic fluctuations in isovalent P-doped BaFe_{2}As_{2} single crystals. Both the ^{75}As and ^{31}P sites exhibit a stretched-exponential relaxation similar to the electron-doped systems. By comparing the hyperfine fields and the relaxation rates at these sites we find that the As relaxation cannot be explained solely in terms of magnetic spin fluctuations. We demonstrate that nematic fluctuations couple to the As nuclear quadrupolar moment and can explain the excess relaxation. These results suggest that glassy nematic dynamics are a common phenomenon in the iron-based superconductors.

    View details for DOI 10.1103/PhysRevLett.116.107202

    View details for Web of Science ID 000371722500009

    View details for PubMedID 27015507

  • Dichroism in the Parent Ferropnictide BaFe2As2 Across the Nematic Phase Transition JOURNAL OF SUPERCONDUCTIVITY AND NOVEL MAGNETISM Chinotti, M., Mirri, C., Dusza, A., Bastelberger, S., Degiorgi, L., Chu, J., Kuo, H., Fisher, I. R. 2016; 29 (3): 667-672
  • Persistent order due to transiently enhanced nesting in an electronically excited charge density wave NATURE COMMUNICATIONS Rettig, L., Cortes, R., Chu, J., Fisher, I. R., Schmitt, F., Moore, R. G., Shen, Z., Kirchmann, P. S., Wolf, M., Bovensiepen, U. 2016; 7

    Abstract

    Non-equilibrium conditions may lead to novel properties of materials with broken symmetry ground states not accessible in equilibrium as vividly demonstrated by non-linearly driven mid-infrared active phonon excitation. Potential energy surfaces of electronically excited states also allow to direct nuclear motion, but relaxation of the excess energy typically excites fluctuations leading to a reduced or even vanishing order parameter as characterized by an electronic energy gap. Here, using femtosecond time- and angle-resolved photoemission spectroscopy, we demonstrate a tendency towards transient stabilization of a charge density wave after near-infrared excitation, counteracting the suppression of order in the non-equilibrium state. Analysis of the dynamic electronic structure reveals a remaining energy gap in a highly excited transient state. Our observation can be explained by a competition between fluctuations in the electronically excited state, which tend to reduce order, and transiently enhanced Fermi surface nesting stabilizing the order.

    View details for DOI 10.1038/ncomms10459

    View details for Web of Science ID 000369023400005

    View details for PubMedID 26804717

  • Origin of the Resistive Anisotropy in the Electronic Nematic Phase of BaFe(2)As(2) Revealed by Optical Spectroscopy. Physical review letters Mirri, C., Dusza, A., Bastelberger, S., Chinotti, M., Degiorgi, L., Chu, J., Kuo, H., Fisher, I. R. 2015; 115 (10): 107001-?

    Abstract

    We perform, as a function of uniaxial stress, an optical-reflectivity investigation of the representative "parent" ferropnictide BaFe_{2}As_{2} in a broad spectral range, across the tetragonal-to-orthorhombic phase transition and the onset of the long-range antiferromagnetic (AFM) order. The infrared response reveals that the dc transport anisotropy in the orthorhombic AFM state is determined by the interplay between the Drude spectral weight and the scattering rate, but that the dominant effect is clearly associated with the metallic spectral weight. In the paramagnetic tetragonal phase, though, the dc resistivity anisotropy of strained samples is almost exclusively due to stress-induced changes in the Drude weight rather than in the scattering rate, definitively establishing the anisotropy of the Fermi surface parameters as the primary effect driving the dc transport properties in the electronic nematic state.

    View details for PubMedID 26382696

  • Origin of the Resistive Anisotropy in the Electronic Nematic Phase of BaFe2As2 Revealed by Optical Spectroscopy PHYSICAL REVIEW LETTERS Mirri, C., Dusza, A., Bastelberger, S., Chinotti, M., Degiorgi, L., Chu, J., Kuo, H., Fisher, I. R. 2015; 115 (10)
  • Transfer of spectral weight across the gap of Sr2IrO4 induced by La doping PHYSICAL REVIEW B Brouet, V., Mansart, J., Perfetti, L., Piovera, C., Vobornik, I., Le Fevre, P., Bertran, F., Riggs, S. C., SHAPIRO, M. C., Giraldo-Gallo, P., Fisher, I. R. 2015; 92 (8)
  • Field-induced spin density wave and spiral phases in a layered antiferromagnet PHYSICAL REVIEW B Stone, M. B., Lumsden, M. D., Garlea, V. O., Grenier, B., Ressouche, E., Samulon, E. C., Fisher, I. R. 2015; 92 (2)
  • Elastoconductivity as a probe of broken mirror symmetries PHYSICAL REVIEW B Hlobil, P., Maharaj, A. V., Hosur, P., SHAPIRO, M. C., Fisher, I. R., Raghu, S. 2015; 92 (3)
  • Observation of universal strong orbital-dependent correlation effects in iron chalcogenides NATURE COMMUNICATIONS Yi, M., Liu, Z., Zhang, Y., Yu, R., Zhu, J., Lee, J. J., Moore, R. G., Schmitt, F. T., Li, W., Riggs, S. C., Chu, J., Lv, B., Hu, J., Hashimoto, M., Mo, S., Hussain, Z., Mao, Z. Q., Chu, C. W., Fisher, I. R., Si, Q., Shen, Z., Lu, D. H. 2015; 6

    View details for DOI 10.1038/ncomms8777

    View details for Web of Science ID 000358859800003

  • Wave-vector-dependent electron-phonon coupling and the charge-density-wave transition in TbTe3 PHYSICAL REVIEW B Maschek, M., Rosenkranz, S., Heid, R., Said, A. H., Giraldo-Gallo, P., Fisher, I. R., Weber, F. 2015; 91 (23)
  • Bulk electronic structure of Zn-Mg-Y and Zn-Mg-Dy icosahedral quasicrystals PHYSICAL REVIEW B Nayak, J., Maniraj, M., Gloskovskii, A., Krajci, M., Sebastian, S., Fisher, I. R., Horn, K., Barman, S. R. 2015; 91 (23)
  • Classification of collective modes in a charge density wave by momentum-dependent modulation of the electronic band structure PHYSICAL REVIEW B Leuenberger, D., Sobota, J. A., Yang, S., Kemper, A. F., Giraldo-Gallo, P., Moore, R. G., Fisher, I. R., Kirchmann, P. S., Devereaux, T. P., Shen, Z. 2015; 91 (20)
  • Pressure dependence of the charge-density-wave and superconducting states in GdTe3, TbTe3, and DyTe3 PHYSICAL REVIEW B Zocco, D. A., Hamlin, J. J., Grube, K., Chu, J., Kuo, H., Fisher, I. R., Maple, M. B. 2015; 91 (20)
  • Monotonic Doping-Dependence in the Anisotropy of the Drude Weight and Scattering Rate of Detwinned Ba(Fe1-x Co (x) )(2)As-2 Established from the Optical Conductivity JOURNAL OF SUPERCONDUCTIVITY AND NOVEL MAGNETISM Dusza, A., Lucarelli, A., Chu, J., Fisher, I. R., Degiorgi, L. 2015; 28 (4): 1261-1266
  • Evidence for a nematic component to the hidden-order parameter in URu2Si2 from differential elastoresistance measurements NATURE COMMUNICATIONS Riggs, S. C., SHAPIRO, M. C., Maharaj, A. V., Raghu, S., Bauer, E. D., Baumbach, R. E., Giraldo-Gallo, P., Wartenbe, M., Fisher, I. R. 2015; 6

    View details for DOI 10.1038/ncomms7425

    View details for Web of Science ID 000352633900009

  • Evidence for a nematic component to the hidden-order parameter in URu2Si2 from differential elastoresistance measurements. Nature communications Riggs, S. C., SHAPIRO, M. C., Maharaj, A. V., Raghu, S., Bauer, E. D., Baumbach, R. E., Giraldo-Gallo, P., Wartenbe, M., Fisher, I. R. 2015; 6: 6425-?

    Abstract

    For materials that harbour a continuous phase transition, the susceptibility of the material to various fields can be used to understand the nature of the fluctuating order and hence the nature of the ordered state. Here we use anisotropic biaxial strain to probe the nematic susceptibility of URu2Si2, a heavy fermion material for which the nature of the low temperature 'hidden order' state has defied comprehensive understanding for over 30 years. Our measurements reveal that the fluctuating order has a nematic component, confirming reports of twofold anisotropy in the broken symmetry state and strongly constraining theoretical models of the hidden-order phase.

    View details for DOI 10.1038/ncomms7425

    View details for PubMedID 25742938

  • Stripe-like nanoscale structural phase separation in superconducting BaPb(1-x)Bi(x)O3. Nature communications Giraldo-Gallo, P., Zhang, Y., Parra, C., Manoharan, H. C., Beasley, M. R., Geballe, T. H., Kramer, M. J., Fisher, I. R. 2015; 6: 8231-?

    Abstract

    The phase diagram of BaPb1-xBixO3 exhibits a superconducting dome in the proximity of a charge density wave phase. For the superconducting compositions, the material coexists as two structural polymorphs. Here we show, via high-resolution transmission electron microscopy, that the structural dimorphism is accommodated in the form of partially disordered nanoscale stripes. Identification of the morphology of the nanoscale structural phase separation enables determination of the associated length scales, which we compare with the Ginzburg-Landau coherence length. We find that the maximum Tc occurs when the superconducting coherence length matches the width of the partially disordered stripes, implying a connection between the structural phase separation and the shape of the superconducting dome.

    View details for DOI 10.1038/ncomms9231

    View details for PubMedID 26373890

  • Observation of universal strong orbital-dependent correlation effects in iron chalcogenides. Nature communications Yi, M., Liu, Z., Zhang, Y., Yu, R., Zhu, J., Lee, J. J., Moore, R. G., Schmitt, F. T., Li, W., Riggs, S. C., Chu, J., Lv, B., Hu, J., Hashimoto, M., Mo, S., Hussain, Z., Mao, Z. Q., Chu, C. W., Fisher, I. R., Si, Q., Shen, Z., Lu, D. H. 2015; 6: 7777-?

    Abstract

    Establishing the appropriate theoretical framework for unconventional superconductivity in the iron-based materials requires correct understanding of both the electron correlation strength and the role of Fermi surfaces. This fundamental issue becomes especially relevant with the discovery of the iron chalcogenide superconductors. Here, we use angle-resolved photoemission spectroscopy to measure three representative iron chalcogenides, FeTe0.56Se0.44, monolayer FeSe grown on SrTiO3 and K0.76Fe1.72Se2. We show that these superconductors are all strongly correlated, with an orbital-selective strong renormalization in the dxy bands despite having drastically different Fermi surface topologies. Furthermore, raising temperature brings all three compounds from a metallic state to a phase where the dxy orbital loses all spectral weight while other orbitals remain itinerant. These observations establish that iron chalcogenides display universal orbital-selective strong correlations that are insensitive to the Fermi surface topology, and are close to an orbital-selective Mott phase, hence placing strong constraints for theoretical understanding of iron-based superconductors.

    View details for DOI 10.1038/ncomms8777

    View details for PubMedID 26204461

  • Disorder driven metal-insulator transition in BaPb(1-x)Bi(x)O3 and inference of disorder-free critical temperature. Physical review letters Luna, K., Giraldo-Gallo, P., Geballe, T., Fisher, I., Beasley, M. 2014; 113 (17): 177004-?

    Abstract

    We performed point-contact spectroscopy tunneling measurements on single crystal BaPb(1-x)Bi(x)O(3) for 0≤x≤0.28 at temperatures T=2-40  K and find a suppression in the density of states at low bias voltages that is characteristic of disordered metals. Both the correlation gap and the zero-temperature conductivity are zero at a critical concentration x(c)=0.30. Not only does this suggests that a disorder driven metal-insulator transition occurs before the onset of the charge disproportionated charge density wave insulator, but we also explore whether a scaling theory is applicable. In addition, we estimate the disorder-free critical temperature and compare these results to Ba(1-x)K(x)BiO(3).

    View details for PubMedID 25379933

  • Disorder Driven Metal-Insulator Transition in BaPb1-xBixO3 and Inference of Disorder-Free Critical Temperature PHYSICAL REVIEW LETTERS Luna, K., Giraldo-Gallo, P., Geballe, T., Fisher, I., Beasley, M. 2014; 113 (17)
  • Nematic-driven anisotropic electronic properties of underdoped detwinned Ba(Fe1-xCox)(2)As-2 revealed by optical spectroscopy PHYSICAL REVIEW B Mirri, C., Dusza, A., Bastelberger, S., Chu, J., Kuo, H., Fisher, I. R., Degiorgi, L. 2014; 90 (15)
  • Distinguishing Bulk and Surface Electron-Phonon Coupling in the Topological Insulator Bi2Se3 Using Time-Resolved Photoemission Spectroscopy PHYSICAL REVIEW LETTERS Sobota, J. A., Yang, S., Leuenberger, D., Kemper, A. F., Analytis, J. G., Fisher, I. R., Kirchmann, P. S., Devereaux, T. P., Shen, Z. 2014; 113 (15)
  • Distinguishing bulk and surface electron-phonon coupling in the topological insulator Bi(2)Se(3) using time-resolved photoemission spectroscopy. Physical review letters Sobota, J. A., Yang, S., Leuenberger, D., Kemper, A. F., Analytis, J. G., Fisher, I. R., Kirchmann, P. S., Devereaux, T. P., Shen, Z. 2014; 113 (15): 157401-?

    Abstract

    We report time- and angle-resolved photoemission spectroscopy measurements on the topological insulator Bi(2)Se(3). We observe oscillatory modulations of the electronic structure of both the bulk and surface states at a frequency of 2.23 THz due to coherent excitation of an A(1g) phonon mode. A distinct, additional frequency of 2.05 THz is observed in the surface state only. The lower phonon frequency at the surface is attributed to the termination of the crystal and thus reduction of interlayer van der Waals forces, which serve as restorative forces for out-of-plane lattice distortions. Density functional theory calculations quantitatively reproduce the magnitude of the surface phonon softening. These results represent the first band-resolved evidence of the A(1g) phonon mode coupling to the surface state in a topological insulator.

    View details for PubMedID 25375740

  • Ultrafast electron dynamics in the topological insulator Bi2Se3 studied by time-resolved photoemission spectroscopy JOURNAL OF ELECTRON SPECTROSCOPY AND RELATED PHENOMENA Sobota, J. A., Yang, S., Leuenberger, D., Kemper, A. F., Analytis, J. G., Fisher, I. R., Kirchmann, P. S., Devereaux, T. P., Shen, Z. 2014; 195: 249-257
  • Bandgap closure and reopening in CsAuI3 at high pressure PHYSICAL REVIEW B Wang, S., Kemper, A. F., Baldini, M., SHAPIRO, M. C., Riggs, S. C., Zhao, Z., Liu, Z., Devereaux, T. P., Geballe, T. H., Fisher, I. R., Mao, W. L. 2014; 89 (24)
  • Effect of disorder on the resistivity anisotropy near the electronic nematic phase transition in pure and electron-doped BaFe(2)As(2). Physical review letters Kuo, H., Fisher, I. R. 2014; 112 (22): 227001-?

    Abstract

    We show that the strain-induced resistivity anisotropy in the tetragonal state of the representative underdoped Fe arsenides BaFe_{2}As_{2}, Ba(Fe_{1-x}Co_{x})_{2}As_{2} and Ba(Fe_{1-x}Ni_{x})_{2}As_{2} is independent of disorder over a wide range of defect and impurity concentrations. This result demonstrates that the anisotropy in the in-plane resistivity in the paramagnetic orthorhombic state of this material is not due to elastic scattering from anisotropic defects. Conversely, our result can be most easily understood if the resistivity anisotropy arises primarily from an intrinsic anisotropy in the electronic structure.

    View details for PubMedID 24949785

  • Effect of Disorder on the Resistivity Anisotropy Near the Electronic Nematic Phase Transition in Pure and Electron-Doped BaFe2As2 PHYSICAL REVIEW LETTERS Kuo, H., Fisher, I. R. 2014; 112 (22)
  • Spectrally resolved femtosecond reflectivity relaxation dynamics in undoped spin-density wave 122-structure iron-based pnictides PHYSICAL REVIEW B Pogrebna, A., Vujicic, N., Mertelj, T., Borzda, T., Cao, G., Xu, Z. A., Chu, J., Fisher, I. R., Mihailovic, D. 2014; 89 (16)
  • Dynamic competition between spin-density wave order and superconductivity in underdoped Ba1-xKxFe2As2 NATURE COMMUNICATIONS Yi, M., Zhang, Y., Liu, Z., Ding, X., Chu, J., Kemper, A. F., Plonka, N., Moritz, B., Hashimoto, M., Mo, S., Hussain, Z., Devereaux, T. P., Fisher, I. R., Wen, H. H., Shen, Z., Lu, D. H. 2014; 5

    View details for DOI 10.1038/ncomms4711

    View details for Web of Science ID 000335223100002

  • Transport near a quantum critical point in BaFe2(As1-xPx)(2) NATURE PHYSICS Analytis, J. G., Kuo, H., McDonald, R. D., Wartenbe, M., Rourke, P. M., Hussey, N. E., Fisher, I. R. 2014; 10 (3): 194-197

    View details for DOI 10.1038/NPHYS2869

    View details for Web of Science ID 000332185900014

  • Hysteretic behavior in the optical response of the underdoped Fe-arsenide Ba(Fe1-xCox)(2)As-2 in the electronic nematic phase PHYSICAL REVIEW B Mirri, C., Dusza, A., Bastelberger, S., Chu, J., Kuo, H., Fisher, I. R., Degiorgi, L. 2014; 89 (6)
  • Coherent dynamics of the charge density wave gap in tritellurides FARADAY DISCUSSIONS Rettig, L., Chu, J., Fisher, I. R., Bovensiepen, U., Wolf, M. 2014; 171: 299-310

    Abstract

    The dynamics of the transient electronic structure in the charge density wave (CDW) system RTe3 (R = rare-earth element) is studied using time- and angle-resolved photoemission spectroscopy (trARPES). Employing a three-pulse pump-probe scheme we investigate the effect of the amplitude mode oscillations on the electronic band structure and, in particular, on the CDW energy gap. We observe coherent oscillations in both lower and upper CDW band with opposite phases, whereby two dominating frequencies are modulating the CDW order parameter. This demonstrates the existence of more than one collective amplitude mode, in contrast to a simple Peierls model. Coherent control experiments of the two amplitude modes, which are strongly coupled in equilibrium, demonstrate independent control of the modes suggesting a decoupling of both modes in the transient photoexcited state.

    View details for DOI 10.1039/c4fd00045e

    View details for Web of Science ID 000345529900016

    View details for PubMedID 25415056

  • Dynamic competition between spin-density wave order and superconductivity in underdoped Ba(1-x)K(x)Fe2As2. Nature communications Yi, M., Zhang, Y., Liu, Z., Ding, X., Chu, J., Kemper, A. F., Plonka, N., Moritz, B., Hashimoto, M., Mo, S., Hussain, Z., Devereaux, T. P., Fisher, I. R., Wen, H. H., Shen, Z., Lu, D. H. 2014; 5: 3711-?

    Abstract

    An intriguing aspect of unconventional superconductivity is that it always appears in the vicinity of other competing phases, whose suppression brings the full emergence of superconductivity. In the iron pnictides, these competing phases are marked by a tetragonal-to-orthorhombic structural transition and a collinear spin-density wave (SDW) transition. There has been macroscopic evidence for competition between these phases and superconductivity as the magnitude of both the orthorhombicity and magnetic moment are suppressed in the superconducting state. Here, using angle-resolved photoemission spectroscopy on detwinned underdoped Ba(1-x)K(x)Fe2As2, we observe a coexistence of both the SDW gap and superconducting gap in the same electronic structure. Furthermore, our data reveal that following the onset of superconductivity, the SDW gap decreases in magnitude and shifts in a direction consistent with a reduction of the orbital anisotropy. This observation provides direct spectroscopic evidence for the dynamic competition between superconductivity and both SDW and electronic nematic orders in these materials.

    View details for DOI 10.1038/ncomms4711

    View details for PubMedID 24762657

  • Direct Optical Coupling to an Unoccupied Dirac Surface State in the Topological Insulator Bi2Se3 PHYSICAL REVIEW LETTERS Sobota, J. A., Yang, S., Kemper, A. F., Lee, J. J., Schmitt, F. T., Li, W., Moore, R. G., Analytis, J. G., Fisher, I. R., Kirchmann, P. S., Devereaux, T. P., Shen, Z. 2013; 111 (13)

    Abstract

    We characterize the occupied and unoccupied electronic structure of the topological insulator Bi2Se3 by one-photon and two-photon angle-resolved photoemission spectroscopy and slab band structure calculations. We reveal a second, unoccupied Dirac surface state with similar electronic structure and physical origin to the well-known topological surface state. This state is energetically located 1.5 eV above the conduction band, which permits it to be directly excited by the output of a Ti:sapphire laser. This discovery demonstrates the feasibility of direct ultrafast optical coupling to a topologically protected, spin-textured surface state.

    View details for DOI 10.1103/PhysRevLett.111.136802

    View details for Web of Science ID 000324762300016

    View details for PubMedID 24116801

  • Measurement of the elastoresistivity coefficients of the underdoped iron arsenide Ba(Fe0.975Co0.025)(2)As-2 PHYSICAL REVIEW B Kuo, H., Shapiro, M. C., Riggs, S. C., Fisher, I. R. 2013; 88 (8)
  • Dynamics of Photoexcited Carriers in Ba(Fe1-xCox)(2)As-2 Single Crystals with Spin-Density-Wave Ordering JOURNAL OF SUPERCONDUCTIVITY AND NOVEL MAGNETISM Stojchevska, L., Mertelj, T., Chu, J., Fisher, I. R., Mihailovic, D. 2013; 26 (8): 2593-2596
  • Inhomogeneous Superconductivity in BaPb1-xBixO3 JOURNAL OF SUPERCONDUCTIVITY AND NOVEL MAGNETISM Giraldo-Gallo, P., Lee, H., Beasley, M. R., Geballe, T. H., Fisher, I. R. 2013; 26 (8): 2675-2678
  • Distribution of Optical Spectral Weight in Detwinned Ba(Fe1-xCox)(2)As-2 JOURNAL OF SUPERCONDUCTIVITY AND NOVEL MAGNETISM Dusza, A., Lucarelli, A., Chu, J., Fisher, I. R., Degiorgi, L. 2013; 26 (8): 2603-2606
  • Direct measurement of current-phase relations in superconductor/topological insulator/superconductor junctions. Nano letters Sochnikov, I., Bestwick, A. J., Williams, J. R., Lippman, T. M., Fisher, I. R., Goldhaber-Gordon, D., Kirtley, J. R., Moler, K. A. 2013; 13 (7): 3086-3092

    Abstract

    Proximity to a superconductor is predicted to induce exotic quantum phases in topological insulators. Here, scanning superconducting quantum interference device (SQUID) microscopy reveals that aluminum superconducting rings with topologically insulating Bi2Se3 junctions exhibit a conventional, nearly sinusoidal 2π-periodic current-phase relations. Pearl vortices occur in longer junctions, indicating suppressed superconductivity in aluminum, probably due to a proximity effect. Our observations establish scanning SQUID as a general tool for characterizing proximity effects and for measuring current-phase relations in new materials systems.

    View details for DOI 10.1021/nl400997k

    View details for PubMedID 23795666

  • Infrared study of the electronic structure of the metallic pyrochlore iridate Bi2Ir2O7 PHYSICAL REVIEW B Lee, Y. S., Moon, S. J., Riggs, S. C., SHAPIRO, M. C., Fisher, I. R., Fulfer, B. W., Chan, J. Y., Kemper, A. F., Basov, D. N. 2013; 87 (19)
  • Charge transfer and multiple density waves in the rare earth tellurides PHYSICAL REVIEW B Banerjee, A., Feng, Y., Silevitch, D. M., Wang, J., Lang, J. C., Kuo, H., Fisher, I. R., Rosenbaum, T. F. 2013; 87 (15)
  • Incoherent Topological Defect Recombination Dynamics in TbTe3 PHYSICAL REVIEW LETTERS Mertelj, T., Kusar, P., Kabanov, V. V., Giraldo-Gallo, P., Fisher, I. R., Mihailovic, D. 2013; 110 (15)
  • Pressure-induced symmetry breaking in tetragonal CsAuI3 PHYSICAL REVIEW B Wang, S., Hirai, S., Shapiro, M. C., Riggs, S. C., Geballe, T. H., Mao, W. L., Fisher, I. R. 2013; 87 (5)
  • Observation of Temperature-Induced Crossover to an Orbital-Selective Mott Phase in A(x)Fe(2-y)Se(2) (A = K, Rb) Superconductors PHYSICAL REVIEW LETTERS Yi, M., Lu, D. H., Yu, R., Riggs, S. C., Chu, J., Lv, B., Liu, Z. K., Lu, M., Cui, Y., Hashimoto, M., Mo, S., Hussain, Z., Chu, C. W., Fisher, I. R., Si, Q., Shen, Z. 2013; 110 (6)

    Abstract

    Using angle-resolved photoemission spectroscopy, we observe the low-temperature state of the A(x)Fe(2-y)Se(2) (A=K, Rb) superconductors to exhibit an orbital-dependent renormalization of the bands near the Fermi level-the d(xy) bands heavily renormalized compared to the d(xz)/d(yz) bands. Upon raising the temperature to above 150 K, the system evolves into a state in which the d(xy) bands have depleted spectral weight while the d(xz)/d(yz) bands remain metallic. Combined with theoretical calculations, our observations can be consistently understood as a temperature-induced crossover from a metallic state at low temperatures to an orbital-selective Mott phase at high temperatures. Moreover, the fact that the superconducting state of A(x)Fe(2-y)Se(2) is near the boundary of such an orbital-selective Mott phase constrains the system to have sufficiently strong on-site Coulomb interactions and Hund's coupling, highlighting the nontrivial role of electron correlation in this family of iron-based superconductors.

    View details for DOI 10.1103/PhysRevLett.110.067003

    View details for Web of Science ID 000314687300031

    View details for PubMedID 23432294

  • Observing electronic structures on ex-situ grown topological insulator thin films PHYSICA STATUS SOLIDI-RAPID RESEARCH LETTERS Yao, S. H., Zhou, B., Lu, M. H., Liu, Z. K., Chen, Y. B., Analytis, J. G., Bruene, C., Dang, W. H., Mo, S., Shen, Z., Fisher, I. R., Molenkamp, L. W., Peng, H. L., Hussain, Z., Chen, Y. L. 2013; 7 (1-2): 130-132
  • Giant atomic displacement at a magnetic phase transition in metastable Mn3O4 PHYSICAL REVIEW B Hirai, S., dos Santos, A. M., SHAPIRO, M. C., Molaison, J. J., Pradhan, N., Guthrie, M., Tulk, C. A., Fisher, I. R., Mao, W. L. 2013; 87 (1)
  • Alternative route to charge density wave formation in multiband systems PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Eiter, H., Lavagnini, M., Hackl, R., Nowadnick, E. A., Kemper, A. F., Devereaux, T. P., Chu, J., Analytis, J. G., Fisher, I. R., Degiorgi, L. 2013; 110 (1): 64-69

    Abstract

    Charge and spin density waves, periodic modulations of the electron, and magnetization densities, respectively, are among the most abundant and nontrivial low-temperature ordered phases in condensed matter. The ordering direction is widely believed to result from the Fermi surface topology. However, several recent studies indicate that this common view needs to be supplemented. Here, we show how an enhanced electron-lattice interaction can contribute to or even determine the selection of the ordering vector in the model charge density wave system ErTe(3). Our joint experimental and theoretical study allows us to establish a relation between the selection rules of the electronic light scattering spectra and the enhanced electron-phonon coupling in the vicinity of band degeneracy points. This alternative proposal for charge density wave formation may be of general relevance for driving phase transitions into other broken-symmetry ground states, particularly in multiband systems, such as the iron-based superconductors.

    View details for DOI 10.1073/pnas.1214745110

    View details for Web of Science ID 000313630300027

  • Vortex structure in BaFe2(As1-x P (x) )(2) single crystals JETP LETTERS Vinnikov, L. Y., Troshina, A. G., Veschunov, I. S., Analytis, D., Fisher, I. R., Liu, Y., Lin, C. T., Fang, L., Welp, U., Kwok, W. K. 2013; 96 (10): 655-658
  • Time-resolved Fermi surface mapping of the charge density wave material DyTe3 XVIIITH INTERNATIONAL CONFERENCE ON ULTRAFAST PHENOMENA Rettig, L., Cortes, R., Chu, J., Fisher, I. R., Schmitt, F., Kirchmann, P. S., Moore, R. G., Shen, Z., Wolf, M., Bovensiepen, U. 2013; 41
  • Controlling the carriers of topological insulators by bulk and surface doping SEMICONDUCTOR SCIENCE AND TECHNOLOGY Zhou, B., Liu, Z. K., Analytis, J. G., Igarashi, K., Mo, S. K., Lu, D. H., Moore, R. G., Fisher, I. R., Sasagawa, T., Shen, Z. X., Hussain, Z., Chen, Y. L. 2012; 27 (12)
  • Magnetoelastically coupled structural, magnetic, and superconducting order parameters in BaFe2(As1-xPx)(2) PHYSICAL REVIEW B Kuo, H., Analytis, J. G., Chu, J., Fernandes, R. M., Schmalian, J., Fisher, I. R. 2012; 86 (13)
  • Single crystal growth by self-flux method of the mixed valence gold halides Cs-2[(AuX2)-X-I][(AuX4)-X-III] (X=Br,I) JOURNAL OF CRYSTAL GROWTH Riggs, S. C., SHAPIRO, M. C., Corredor, F., Geballe, T. H., Fisher, I. R., McCandless, G. T., Chan, J. Y. 2012; 355 (1): 13-16
  • Divergent Nematic Susceptibility in an Iron Arsenide Superconductor SCIENCE Chu, J., Kuo, H., Analytis, J. G., Fisher, I. R. 2012; 337 (6095): 710-712

    Abstract

    Within the Landau paradigm of continuous phase transitions, ordered states of matter are characterized by a broken symmetry. Although the broken symmetry is usually evident, determining the driving force behind the phase transition can be complicated by coupling between distinct order parameters. We show how measurement of the divergent nematic susceptibility of the iron pnictide superconductor Ba(Fe(1-x)Co(x))(2)As(2) distinguishes an electronic nematic phase transition from a simple ferroelastic distortion. These measurements also indicate an electronic nematic quantum phase transition near the composition with optimal superconducting transition temperature.

    View details for DOI 10.1126/science.1221713

    View details for Web of Science ID 000307354500048

    View details for PubMedID 22879513

  • Unconventional Josephson Effect in Hybrid Superconductor-Topological Insulator Devices PHYSICAL REVIEW LETTERS Williams, J. R., Bestwick, A. J., Gallagher, P., Hong, S. S., Cui, Y., Bleich, A. S., Analytis, J. G., Fisher, I. R., Goldhaber-Gordon, D. 2012; 109 (5)

    Abstract

    We report on transport properties of Josephson junctions in hybrid superconducting-topological insulator devices, which show two striking departures from the common Josephson junction behavior: a characteristic energy that scales inversely with the width of the junction, and a low characteristic magnetic field for suppressing supercurrent. To explain these effects, we propose a phenomenological model which expands on the existing theory for topological insulator Josephson junctions.

    View details for DOI 10.1103/PhysRevLett.109.056803

    View details for Web of Science ID 000306944200002

    View details for PubMedID 23006196

  • Doping dependence of femtosecond quasiparticle relaxation dynamics in Ba(Fe,Co)(2)As-2 single crystals: Evidence for normal-state nematic fluctuations PHYSICAL REVIEW B Stojchevska, L., Mertelj, T., Chu, J., Fisher, I. R., Mihailovic, D. 2012; 86 (2)
  • Susceptibility Anisotropy in an Iron Arsenide Superconductor Revealed by X-Ray Diffraction in Pulsed Magnetic Fields PHYSICAL REVIEW LETTERS Ruff, J. P., Chu, J., Kuo, H., Das, R. K., Nojiri, H., Fisher, I. R., Islam, Z. 2012; 109 (2)

    Abstract

    In addition to unconventional high-T(c) superconductivity, the iron arsenides exhibit strong magnetoelastic coupling and a notable electronic anisotropy within the a-b plane. We relate these properties by studying underdoped Ba(Fe(1-x)Co(x))2As2 by x-ray diffraction in pulsed magnetic fields up to 27.5 T. We exploit magnetic detwinning effects to demonstrate anisotropy in the in-plane susceptibility, which develops at the structural phase transition despite the absence of magnetic order. The degree of detwinning increases smoothly with decreasing temperature, and a single-domain condition is realized over a range of field and temperature. At low temperatures we observe an activated behavior, with a large hysteretic remnant effect. Detwinning was not observed within the superconducting phase for accessible magnetic fields.

    View details for DOI 10.1103/PhysRevLett.109.027004

    View details for Web of Science ID 000306325900016

    View details for PubMedID 23030198

  • Structure and magnetic properties of the pyrochlore iridate Y2Ir2O7 PHYSICAL REVIEW B SHAPIRO, M. C., Riggs, S. C., Stone, M. B., de la Cruz, C. R., Chi, S., Podlesnyak, A. A., Fisher, I. R. 2012; 85 (21)
  • Infrared and Raman investigation of the charge-density-wave state in rare-earth tri-telluride compounds Lavagnini, M., Pfuner, F., Monnier, R., Degiorgi, L., Eiter, H., Tassini, L., Muschler, B., Hackl, R., Chu, J., Ru, N., Shin, K. Y., Fisher, I. R. ELSEVIER SCIENCE BV. 2012: 1864-1867
  • STM Imaging of Impurity Resonances on Bi2Se3 PHYSICAL REVIEW LETTERS Alpichshev, Z., Biswas, R. R., Balatsky, A. V., Analytis, J. G., Chu, J., Fisher, I. R., Kapitulnik, A. 2012; 108 (20)

    Abstract

    In this Letter we present detailed study of the density of states near defects in Bi2Se3. In particular, we present data on the commonly found triangular defects in this system. While we do not find any measurable quasiparticle scattering interference effects, we do find localized resonances, which can be well fitted by theory [R.?R. Biswas and A.?V. Balatsky, Phys. Rev. B 81, 233405(R) (2010)] once the potential is taken to be extended to properly account for the observed defects. The data together with the fits confirm that while the local density of states around the Dirac point of the electronic spectrum at the surface is significantly disrupted near the impurity by the creation of low-energy resonance state, the Dirac point is not locally destroyed. We discuss our results in terms of the expected protected surface state of topological insulators.

    View details for DOI 10.1103/PhysRevLett.108.206402

    View details for Web of Science ID 000304064000013

    View details for PubMedID 23003161

  • Field-tuned superconductor-insulator transition in BaPb1-xBixO3 PHYSICAL REVIEW B Lee, H., Zhang, Y., Kramer, M. J., Beasley, M. R., Geballe, T. H., Fisher, I. R. 2012; 85 (17)
  • Resonant enhancement of charge density wave diffraction in the rare-earth tritellurides PHYSICAL REVIEW B Lee, W. S., Sorini, A. P., Yi, M., Chuang, Y. D., Moritz, B., Yang, W. L., Chu, J., Kuo, H. H., Gonzalez, A. G., Fisher, I. R., Hussain, Z., Devereaux, T. P., Shen, Z. X. 2012; 85 (15)
  • Pressure dependence of the BaFe2As2 Fermi surface within the spin density wave state PHYSICAL REVIEW B Graf, D., Stillwell, R., Murphy, T. P., Park, J., Palm, E. C., Schlottmann, P., McDonald, R. D., Analytis, J. G., Fisher, I. R., Tozer, S. W. 2012; 85 (13)
  • Ultrafast Optical Excitation of a Persistent Surface-State Population in the Topological Insulator Bi2Se3 PHYSICAL REVIEW LETTERS Sobota, J. A., Yang, S., Analytis, J. G., Chen, Y. L., Fisher, I. R., Kirchmann, P. S., Shen, Z. 2012; 108 (11)

    Abstract

    Using femtosecond time- and angle-resolved photoemission spectroscopy, we investigated the nonequilibrium dynamics of the topological insulator Bi2Se3. We studied p-type Bi2Se3, in which the metallic Dirac surface state and bulk conduction bands are unoccupied. Optical excitation leads to a metastable population at the bulk conduction band edge, which feeds a nonequilibrium population of the surface state persisting for >10 ps. This unusually long-lived population of a metallic Dirac surface state with spin texture may present a channel in which to drive transient spin-polarized currents.

    View details for DOI 10.1103/PhysRevLett.108.117403

    View details for Web of Science ID 000301478400014

    View details for PubMedID 22540508

  • Anisotropic in-plane optical conductivity in detwinned Ba(Fe1-xCox)(2)As-2 NEW JOURNAL OF PHYSICS Dusza, A., Lucarelli, A., Sanna, A., Massidda, S., Chu, J., Fisher, I. R., Degiorgi, L. 2012; 14
  • Ultrafast pump-probe measurements of short small-polaron lifetimes in the mixed-valence perovskite Cs2Au2I6 under high pressures PHYSICAL REVIEW B Trigo, M., Chen, J., Jiang, M. P., Mao, W. L., Riggs, S. C., SHAPIRO, M. C., Fisher, I. R., Reis, D. A. 2012; 85 (8)
  • Robust topological surface state against direct surface contamination PHYSICA E-LOW-DIMENSIONAL SYSTEMS & NANOSTRUCTURES Liu, Z. K., Chen, Y. L., Analytis, J. G., Mo, S. K., Lu, D. H., Moore, R. G., Fisher, I. R., Hussain, Z., Shen, Z. X. 2012; 44 (5): 891-894
  • Incommensurate magnetic order in TbTe3 JOURNAL OF PHYSICS-CONDENSED MATTER Pfuner, F., Gvasaliya, S. N., Zaharko, O., Keller, L., Mesot, J., Pomjakushin, V., Chu, J., Fisher, I. R., Degiorgi, L. 2012; 24 (3)

    Abstract

    We report a neutron diffraction study of the magnetic phase transitions in the charge-density wave (CDW) TbTe(3) compound. We discover that in the paramagnetic phase there are strong 2D-like magnetic correlations, consistent with the pronounced anisotropy of the chemical structure. A long-range incommensurate magnetic order emerges in TbTe(3) at T(mag1) = 5.78 K as a result of continuous phase transitions. We observe that near the temperature T(mag1) the magnetic Bragg peaks appear around the position (0, 0, 0.24) (or its rational multiples), that is fairly close to the propagation vector (0,0,0.29) associated with the CDW phase transition in TbTe(3). This suggests that correlations leading to the long-range magnetic order in TbTe(3) are linked to the modulations that occur in the CDW state.

    View details for DOI 10.1088/0953-8984/24/3/036001

    View details for Web of Science ID 000298641600017

    View details for PubMedID 22156023

  • Low-energy quasiparticles probed by heat transport in the iron-based superconductor LaFePO PHYSICAL REVIEW B Sutherland, M., Dunn, J., Toews, W. H., O'Farrell, E., Analytis, J., Fisher, I., Hill, R. W. 2012; 85 (1)
  • Principles of crystal growth of intermetallic and oxide compounds from molten solutions PHILOSOPHICAL MAGAZINE Fisher, I. R., SHAPIRO, M. C., Analytis, J. G. 2012; 92 (19-21): 2401-2435
  • Superconductivity, spin and charge order, and quantum criticality in correlated electron materials EURASIA-PACIFIC SUMMER SCHOOL AND CONFERENCE ON CORRELATED ELECTRONS Maple, M. B., Hamlin, J. J., Zocco, D. A., Janoschek, M., Baumbach, R. E., White, B. D., Fisher, I. R., Chu, J. 2012; 23
  • In-plane electronic anisotropy of underdoped '122' Fe-arsenide superconductors revealed by measurements of detwinned single crystals REPORTS ON PROGRESS IN PHYSICS Fisher, I. R., Degiorgi, L., Shen, Z. X. 2011; 74 (12)
  • Ambipolar field effect in the ternary topological insulator (BixSb1-x)(2)Te-3 by composition tuning NATURE NANOTECHNOLOGY Kong, D., Chen, Y., Cha, J. J., Zhang, Q., Analytis, J. G., Lai, K., Liu, Z., Hong, S. S., Koski, K. J., Mo, S., Hussain, Z., Fisher, I. R., Shen, Z., Cui, Y. 2011; 6 (11): 705-709

    Abstract

    Topological insulators exhibit a bulk energy gap and spin-polarized surface states that lead to unique electronic properties, with potential applications in spintronics and quantum information processing. However, transport measurements have typically been dominated by residual bulk charge carriers originating from crystal defects or environmental doping, and these mask the contribution of surface carriers to charge transport in these materials. Controlling bulk carriers in current topological insulator materials, such as the binary sesquichalcogenides Bi2Te3, Sb2Te3 and Bi2Se3, has been explored extensively by means of material doping and electrical gating, but limited progress has been made to achieve nanostructures with low bulk conductivity for electronic device applications. Here we demonstrate that the ternary sesquichalcogenide (Bi(x)Sb(1-x))2Te3 is a tunable topological insulator system. By tuning the ratio of bismuth to antimony, we are able to reduce the bulk carrier density by over two orders of magnitude, while maintaining the topological insulator properties. As a result, we observe a clear ambipolar gating effect in (Bi(x)Sb(1-x))2Te3 nanoplate field-effect transistor devices, similar to that observed in graphene field-effect transistor devices. The manipulation of carrier type and density in topological insulator nanostructures demonstrated here paves the way for the implementation of topological insulators in nanoelectronics and spintronics.

    View details for DOI 10.1038/NNANO.2011.172

    View details for Web of Science ID 000296737300007

    View details for PubMedID 21963714

  • Persistence of magnons in a site-diluted dimerized frustrated antiferromagnet JOURNAL OF PHYSICS-CONDENSED MATTER Stone, M. B., Podlesnyak, A., Ehlers, G., Huq, A., Samulon, E. C., SHAPIRO, M. C., Fisher, I. R. 2011; 23 (41)

    Abstract

    We present inelastic neutron scattering and thermodynamic measurements characterizing the magnetic excitations in a disordered spin-liquid antiferromagnet with non-magnetic substitution. The parent compound Ba(3)Mn(2)O(8) is a dimerized, quasi-two-dimensional geometrically frustrated quantum disordered antiferromagnet. We substitute this compound with non-magnetic V(5+) for the S=1 Mn(5+) ions, Ba(3)(Mn(1-x)V (x))(2)O(8), and find that the singlet-triplet excitations which dominate the spectrum of the parent compound persist for the full range of substitution examined, up to x=0.3. We also observe additional low-energy magnetic fluctuations which are enhanced at the greatest substitution values.

    View details for DOI 10.1088/0953-8984/23/41/416003

    View details for Web of Science ID 000295842100016

    View details for PubMedID 21952109

  • Widespread spin polarization effects in photoemission from topological insulators PHYSICAL REVIEW B Jozwiak, C., Chen, Y. L., Fedorov, A. V., Analytis, J. G., Rotundu, C. R., Schmid, A. K., Denlinger, J. D., Chuang, Y., Lee, D., Fisher, I. R., Birgeneau, R. J., Shen, Z., Hussain, Z., Lanzara, A. 2011; 84 (16)
  • Polarized neutron diffraction study of the field-induced magnetization in the normal and superconducting states of Ba(Fe1-xCox)(2)As-2 (x=0.65) PHYSICAL REVIEW B Lester, C., Chu, J., Analytis, J. G., Stunault, A., Fisher, I. R., Hayden, S. M. 2011; 84 (13)
  • Revealing the dual nature of magnetism in iron pnictides and iron chalcogenides using x-ray emission spectroscopy PHYSICAL REVIEW B Gretarsson, H., Lupascu, A., Kim, J., Casa, D., Gog, T., Wu, W., Julian, S. R., Xu, Z. J., Wen, J. S., Gu, G. D., Yuan, R. H., Chen, Z. G., Wang, N., Khim, S., Kim, K. H., Ishikado, M., Jarrige, I., Shamoto, S., Chu, J., Fisher, I. R., Kim, Y. 2011; 84 (10)
  • Possible origin of the nonmonotonic doping dependence of the in-plane resistivity anisotropy of Ba(Fe(1)xT(x))(2)As-2 (T = Co, Ni and Cu) PHYSICAL REVIEW B Kuo, H., Chu, J., Riggs, S. C., Yu, L., McMahon, P. L., De Greve, K., Yamamoto, Y., Analytis, J. G., Fisher, I. R. 2011; 84 (5)
  • Nonuniversal magnetization at the BEC critical field: Application to the spin dimer compound Ba3Mn2O8 PHYSICAL REVIEW B Suh, S., Al-Hassanieh, K. A., Samulon, E. C., Fisher, I. R., Brown, S. E., Batista, C. D. 2011; 84 (5)
  • Heat capacity of the site-diluted spin dimer system Ba-3(Mn1-xVx)(2)O-8 PHYSICAL REVIEW B Samulon, E. C., SHAPIRO, M. C., Fisher, I. R. 2011; 84 (5)
  • STM imaging of a bound state along a step on the surface of the topological insulator Bi2Te3 PHYSICAL REVIEW B Alpichshev, Z., Analytis, J. G., Chu, J., Fisher, I. R., Kapitulnik, A. 2011; 84 (4)
  • Ultrafast electron dynamics in the charge density wave material TbTe3 NEW JOURNAL OF PHYSICS Schmitt, F., Kirchmann, P. S., Bovensiepen, U., Moore, R. G., Chu, J., Lu, D. H., Rettig, L., Wolf, M., Fisher, I. R., Shen, Z. 2011; 13
  • Rapid Surface Oxidation as a Source of Surface Degradation Factor for Bi2Se3 ACS NANO Kong, D., Cha, J. J., Lai, K., Peng, H., Analytis, J. G., Meister, S., Chen, Y., Zhang, H., Fisher, I. R., Shen, Z., Cui, Y. 2011; 5 (6): 4698-4703

    Abstract

    Bismuth selenide (Bi(2)Se(3)) is a topological insulator with metallic surface states (SS) residing in a large bulk bandgap. In experiments, synthesized Bi(2)Se(3) is often heavily n-type doped due to selenium vacancies. Furthermore, it is discovered from experiments on bulk single crystals that Bi(2)Se(3) gets additional n-type doping after exposure to the atmosphere, thereby reducing the relative contribution of SS in total conductivity. In this article, transport measurements on Bi(2)Se(3) nanoribbons provide additional evidence of such environmental doping process. Systematic surface composition analyses by X-ray photoelectron spectroscopy reveal fast formation and continuous growth of native oxide on Bi(2)Se(3) under ambient conditions. In addition to n-type doping at the surface, such surface oxidation is likely the material origin of the degradation of topological SS. Appropriate surface passivation or encapsulation may be required to probe topological SS of Bi(2)Se(3) by transport measurements.

    View details for DOI 10.1021/nn200556h

    View details for Web of Science ID 000292055200052

    View details for PubMedID 21568290

  • Symmetry-breaking orbital anisotropy observed for detwinned Ba(Fe1-xCox)(2)As-2 above the spin density wave transition PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Yi, M., Lu, D., Chu, J., Analytis, J. G., Sorini, A. P., Kemper, A. F., Moritz, B., Mo, S., Moore, R. G., Hashimoto, M., Lee, W., Hussain, Z., Devereaux, T. P., Fisher, I. R., Shen, Z. 2011; 108 (17): 6878-6883
  • Femtosecond Coherent Non-equilibrium Electronic Ordering and Dynamics of Topological Defect in Charge Density Waves JOURNAL OF SUPERCONDUCTIVITY AND NOVEL MAGNETISM Yusupov, R., Mertelj, T., Kabanov, V. V., Kusar, P., Mihailovic, D., Chu, J., Fisher, I. R., Brazovskii, S. 2011; 24 (3): 1191-1193
  • Behavior of vortices near twin boundaries in underdoped Ba(Fe1-xCox)(2)As-2 PHYSICAL REVIEW B Kalisky, B., Kirtley, J. R., Analytis, J. G., Chu, J., Fisher, I. R., Moler, K. A. 2011; 83 (6)
  • Local Measurement of the Superfluid Density in the Pnictide Superconductor Ba(Fe1-xCox)(2)As-2 across the Superconducting Dome PHYSICAL REVIEW LETTERS Luan, L., Lippman, T. M., Hicks, C. W., Bert, J. A., Auslaender, O. M., Chu, J., Analytis, J. G., Fisher, I. R., Moler, K. A. 2011; 106 (6)

    Abstract

    We measure the penetration depth ?ab(T) in Ba(Fe(1-x)Co(x))(2)As(2) using local techniques that do not average over the sample. The superfluid density ?s(T) ? 1/?ab(T)2 has three main features. First, ?s (T = 0) falls sharply on the underdoped side of the dome. Second, ?ab(T) is flat at low T at optimal doping, indicating fully gapped superconductivity, but varies more strongly in underdoped and overdoped samples, consistent with either a power law or a small second gap. Third, ?s (T) varies steeply near Tc for optimal and underdoping. These observations are consistent with an interplay between magnetic and superconducting phases.

    View details for DOI 10.1103/PhysRevLett.106.067001

    View details for Web of Science ID 000287135400006

    View details for PubMedID 21405485

  • Anisotropic charge dynamics in detwinned Ba(Fe1-xCox)(2)As-2 EPL Dusza, A., Lucarelli, A., Pfuner, F., Chu, J., Fisher, I. R., Degiorgi, L. 2011; 93 (3)
  • Anharmonic order-parameter oscillations and lattice coupling in strongly driven 1T-TaS2 and TbTe3 charge-density-wave compounds: A multiple-pulse femtosecond laser spectroscopy study PHYSICAL REVIEW B Kusar, P., Mertelj, T., Kabanov, V. V., Chu, J., Fisher, I. R., Berger, H., Forro, L., Mihailovic, D. 2011; 83 (3)
  • Single Dirac Cone Topological Surface State and Unusual Thermoelectric Property of Compounds from a New Topological Insulator Family PHYSICAL REVIEW LETTERS Chen, Y. L., Liu, Z. K., Analytis, J. G., Chu, J., Zhang, H. J., Yan, B. H., Mo, S., Moore, R. G., Lu, D. H., Fisher, I. R., Zhang, S. C., Hussain, Z., Shen, Z. 2010; 105 (26)

    Abstract

    Angle resolved photoemission spectroscopy study on TlBiTe2 and TlBiSe2 from a thallium-based ternary chalcogenides family revealed a single surface Dirac cone at the center of the Brillouin zone for both compounds. For TlBiSe2, the large bulk gap (?200 meV) makes it a topological insulator with better mechanical properties than the previous binary 3D topological insualtor family. For TlBiTe2, the observed negative bulk gap indicates it as a semimetal, instead of a narrow-gap semiconductor as conventionally believed; this semimetality naturally explains its mysteriously small thermoelectric figure of merit comparing to other compounds in the family. Finally, the unique band structures of TlBiTe2 also suggest it as a candidate for topological superconductors.

    View details for DOI 10.1103/PhysRevLett.105.266401

    View details for Web of Science ID 000286754700014

    View details for PubMedID 21231687

  • Two-dimensional surface state in the quantum limit of a topological insulator NATURE PHYSICS Analytis, J. G., McDonald, R. D., Riggs, S. C., Chu, J., Boebinger, G. S., Fisher, I. R. 2010; 6 (12): 960-964

    View details for DOI 10.1038/NPHYS1861

    View details for Web of Science ID 000284832600015

  • Enhanced Fermi-Surface Nesting in Superconducting BaFe2(As1-xPx)(2) Revealed by the de Haas-van Alphen Effect PHYSICAL REVIEW LETTERS Analytis, J. G., Chu, J., McDonald, R. D., Riggs, S. C., Fisher, I. R. 2010; 105 (20)

    Abstract

    The three-dimensional Fermi-surface morphology of superconducting BaFe2(As0.37P0.63)2 with T(c)=9??K is determined using the de Haas-van Alphen effect. The inner electron pocket has a similar area and k(z) interplane warping to the observed hole pocket, revealing that the Fermi surfaces are geometrically well nested in the (?,?) direction. These results are in stark contrast to the fermiology of the nonsuperconducting phosphides (x=1), and therefore suggest an important role for nesting in pnictide superconductivity.

    View details for DOI 10.1103/PhysRevLett.105.207004

    View details for Web of Science ID 000284147800011

    View details for PubMedID 21231258

  • Pinpointing gap minima in Ba(Fe0.94Co0.06)(2)As-2 via band-structure calculations and electronic Raman scattering PHYSICAL REVIEW B Mazin, I. I., Devereaux, T. P., Analytis, J. G., Chu, J., Fisher, I. R., Muschler, B., Hackl, R. 2010; 82 (18)
  • Coherent dynamics of macroscopic electronic order through a symmetry breaking transition NATURE PHYSICS Yusupov, R., Mertelj, T., Kabanov, V. V., Brazovskii, S., Kusar, P., Chu, J., Fisher, I. R., Mihailovic, D. 2010; 6 (9): 681-684

    View details for DOI 10.1038/NPHYS1738

    View details for Web of Science ID 000281540200017

  • In-Plane Resistivity Anisotropy in an Underdoped Iron Arsenide Superconductor SCIENCE Chu, J., Analytis, J. G., De Greve, K., McMahon, P. L., Islam, Z., Yamamoto, Y., Fisher, I. R. 2010; 329 (5993): 824-826

    Abstract

    High-temperature superconductivity often emerges in the proximity of a symmetry-breaking ground state. For superconducting iron arsenides, in addition to the antiferromagnetic ground state, a small structural distortion breaks the crystal's C(4 )rotational symmetry in the underdoped part of the phase diagram. We reveal that the representative iron arsenide Ba(Fe(1)(-x)Co(x))(2)As(2) develops a large electronic anisotropy at this transition via measurements of the in-plane resistivity of detwinned single crystals, with the resistivity along the shorter b axis rho(b) being greater than rho(a). The anisotropy reaches a maximum value of ~2 for compositions in the neighborhood of the beginning of the superconducting dome. For temperatures well above the structural transition, uniaxial stress induces a resistivity anisotropy, indicating a substantial nematic susceptibility.

    View details for DOI 10.1126/science.1190482

    View details for Web of Science ID 000280809900046

    View details for PubMedID 20705856

  • Massive Dirac Fermion on the Surface of a Magnetically Doped Topological Insulator SCIENCE Chen, Y. L., Chu, J., Analytis, J. G., Liu, Z. K., Igarashi, K., Kuo, H., Qi, X. L., Mo, S. K., Moore, R. G., Lu, D. H., Hashimoto, M., Sasagawa, T., Zhang, S. C., Fisher, I. R., Hussain, Z., Shen, Z. X. 2010; 329 (5992): 659-662

    Abstract

    In addition to a bulk energy gap, topological insulators accommodate a conducting, linearly dispersed Dirac surface state. This state is predicted to become massive if time reversal symmetry is broken, and to become insulating if the Fermi energy is positioned inside both the surface and bulk gaps. We introduced magnetic dopants into the three-dimensional topological insulator dibismuth triselenide (Bi2Se3) to break the time reversal symmetry and further position the Fermi energy inside the gaps by simultaneous magnetic and charge doping. The resulting insulating massive Dirac fermion state, which we observed by angle-resolved photoemission, paves the way for studying a range of topological phenomena relevant to both condensed matter and particle physics.

    View details for DOI 10.1126/science.1189924

    View details for Web of Science ID 000280602700032

    View details for PubMedID 20689013

  • Charge dynamics of Co-doped BaFe2As2 NEW JOURNAL OF PHYSICS Lucarelli, A., Dusza, A., Pfuner, F., Lerch, P., Analytis, J. G., Chu, J., Fisher, I. R., Degiorgi, L. 2010; 12
  • In-plane electronic anisotropy in underdoped Ba(Fe1-xCox)(2)As-2 revealed by partial detwinning in a magnetic field PHYSICAL REVIEW B Chu, J., Analytis, J. G., Press, D., De Greve, K., Ladd, T. D., Yamamoto, Y., Fisher, I. R. 2010; 81 (21)
  • Temperature dependence of the excitation spectrum in the charge-density-wave ErTe3 and HoTe3 systems PHYSICAL REVIEW B Pfuner, F., Lerch, P., Chu, J., Kuo, H., Fisher, I. R., Degiorgi, L. 2010; 81 (19)
  • Bulk Fermi surface coexistence with Dirac surface state in Bi2Se3: A comparison of photoemission and Shubnikov-de Haas measurements PHYSICAL REVIEW B Analytis, J. G., Chu, J., Chen, Y., Corredor, F., McDonald, R. D., Shen, Z. X., Fisher, I. R. 2010; 81 (20)
  • Stripes of increased diamagnetic susceptibility in underdoped superconducting Ba(Fe(1-x)Cox)(2)As-2 single crystals: Evidence for an enhanced superfluid density at twin boundaries PHYSICAL REVIEW B Kalisky, B., Kirtley, J. R., Analytis, J. G., Chu, J., Vailionis, A., Fisher, I. R., Moler, K. A. 2010; 81 (18)
  • Correlation of anomalous normal state properties with superconductivity in Pb1-x-yTlxInyTe PHYSICAL REVIEW B Erickson, A. S., Breznay, N. P., Nowadnick, E. A., Geballe, T. H., Fisher, I. R. 2010; 81 (13)
  • Local measurement of the penetration depth in the pnictide superconductor Ba(Fe0.95Co0.05)(2)As-2 PHYSICAL REVIEW B Luan, L., Auslaender, O. M., Lippman, T. M., Hicks, C. W., Kalisky, B., Chu, J., Analytis, J. G., Fisher, I. R., Kirtley, J. R., Moler, K. A. 2010; 81 (10)
  • Anisotropic phase diagram of the frustrated spin dimer compound Ba3Mn2O8 PHYSICAL REVIEW B Samulon, E. C., Al-Hassanieh, K. A., Jo, Y., SHAPIRO, M. C., Balicas, L., Batista, C. D., Fisher, I. R. 2010; 81 (10)
  • Dispersive spin fluctuations in the nearly optimally doped superconductor Ba(Fe1-xCox)(2)As-2 (x=0.065) PHYSICAL REVIEW B Lester, C., Chu, J., Analytis, J. G., Perring, T. G., Fisher, I. R., Hayden, S. M. 2010; 81 (6)
  • Microwave surface impedance measurements of T1(x)Pb(1-x)Te: A proposed negative-U induced superconductor PHYSICAL REVIEW B BAKER, P. J., Ormeno, R. J., Gough, C. E., Matsushita, Y., Fisher, I. R. 2010; 81 (6)
  • Fermi surface evolution across multiple charge density wave transitions in ErTe3 PHYSICAL REVIEW B Moore, R. G., Brouet, V., He, R., Lu, D. H., Ru, N., Chu, J., Fisher, I. R., Shen, Z. 2010; 81 (7)
  • Raman scattering evidence for a cascade evolution of the charge-density-wave collective amplitude mode PHYSICAL REVIEW B Lavagnini, M., Eiter, H., Tassini, L., Muschler, B., Hackl, R., Monnier, R., Chu, J., Fisher, I. R., Degiorgi, L. 2010; 81 (8)
  • Bulk electronic structure of optimally doped Ba(Fe1-xCox)(2)As-2 PHYSICAL REVIEW B Utfeld, C., Laverock, J., Haynes, T. D., Dugdale, S. B., Duffy, J. A., Butchers, M. W., Taylor, J. W., Giblin, S. R., Analytis, J. G., Chu, J., Fisher, I. R., Itou, M., Sakurai, Y. 2010; 81 (6)
  • Observation of two separate charge density wave transitions in Gd2Te5 via transmission electron microscopy and high-resolution X-ray diffraction JOURNAL OF ALLOYS AND COMPOUNDS Shin, K. Y., Ru, N., Fisher, I. R., Condron, C. L., Toney, M. F., Wu, Y. Q., Kramer, M. J. 2010; 489 (2): 332-335
  • STM Imaging of Electronic Waves on the Surface of Bi2Te3: Topologically Protected Surface States and Hexagonal Warping Effects PHYSICAL REVIEW LETTERS Alpichshev, Z., Analytis, J. G., Chu, J., Fisher, I. R., Chen, Y. L., Shen, Z. X., Fang, A., Kapitulnik, A. 2010; 104 (1)

    Abstract

    Scanning tunneling spectroscopy studies on high-quality Bi2Te3 crystals exhibit perfect correspondence to angle-resolved photoemission spectroscopy data, hence enabling identification of different regimes measured in the local density of states (LDOS). Oscillations of LDOS near a step are analyzed. Within the main part of the surface band oscillations are strongly damped, supporting the hypothesis of topological protection. At higher energies, as the surface band becomes concave, oscillations appear, dispersing with a wave vector that may result from a hexagonal warping term.

    View details for DOI 10.1103/PhysRevLett.104.016401

    View details for Web of Science ID 000273881900022

    View details for PubMedID 20366373

  • Evidence for a charge Kondo effect in Pb1-xTlxTe from measurements of thermoelectric power PHYSICAL REVIEW B Matusiak, M., Tunnicliffe, E. M., Cooper, J. R., Matsushita, Y., Fisher, I. R. 2009; 80 (22)
  • Unconventional electronic reconstruction in undoped (Ba,Sr)Fe2As2 across the spin density wave transition PHYSICAL REVIEW B Yi, M., Lu, D. H., Analytis, J. G., Chu, J., Mo, S., He, R., Hashimoto, M., Moore, R. G., Mazin, I. I., Singh, D. J., Hussain, Z., Fisher, I. R., Shen, Z. 2009; 80 (17)
  • Band- and momentum-dependent electron dynamics in superconducting Ba(Fe1-xCox)(2)As-2 as seen via electronic Raman scattering PHYSICAL REVIEW B Muschler, B., PRESTEL, W., Hackl, R., Devereaux, T. P., Analytis, J. G., Chu, J., Fisher, I. R. 2009; 80 (18)
  • New correlated electron physics from new materials PHYSICA B-CONDENSED MATTER Maple, M. B., Baumbach, R. E., Hamlin, J. J., Zocco, D. A., Taylor, B. J., Butch, N. P., Jeffries, J. R., Weir, S. T., Sales, B. C., Mandrus, D., McGuire, M. A., Sefat, A. S., Jin, R., Vohra, Y. K., Chu, J., Fisher, I. R. 2009; 404 (19): 2924-2929
  • Evidence for a Nodal Energy Gap in the Iron-Pnictide Superconductor LaFePO from Penetration Depth Measurements by Scanning SQUID Susceptometry PHYSICAL REVIEW LETTERS Hicks, C. W., Lippman, T. M., Huber, M. E., Analytis, J. G., Chu, J., Erickson, A. S., Fisher, I. R., Moler, K. A. 2009; 103 (12)

    Abstract

    We measure changes in the penetration depth lambda of the T_{c} approximately 6 K superconductor LaFePO. In the process, scanning SQUID susceptometry is demonstrated as a technique for accurately measuring local temperature-dependent changes in lambda, ideal for studying early or difficult-to-grow materials. lambda is found to vary linearly with temperatures from 0.36 to approximately 2 K, with a slope of 143 +/- 15 A/K, suggesting line nodes in the superconducting order parameter. The linear dependence up to approximately T_{c}/3, similar to the cuprate superconductors, indicates well-developed nodes.

    View details for DOI 10.1103/PhysRevLett.103.127003

    View details for Web of Science ID 000270139000041

    View details for PubMedID 19792454

  • Fermi Surface of SrFe2P2 Determined by the de Haas-van Alphen Effect PHYSICAL REVIEW LETTERS Analytis, J. G., Andrew, C. M., Coldea, A. I., McCollam, A., Chu, J., McDonald, R. D., Fisher, I. R., Carrington, A. 2009; 103 (7)

    Abstract

    We report measurements of the Fermi surface (FS) of the ternary iron-phosphide SrFe2P2 using the de Haas-van Alphen effect. The calculated FS of this compound is very similar to SrFe2As2, the parent compound of the high temperature superconductors. Our data show that the Fermi surface is composed of two electron and two hole sheets in agreement with band-structure calculations. Several of the sheets show strong c-axis warping emphasizing the importance of three dimensionality in the nonmagnetic state of the ternary pnictides. We find that the electron and hole pockets have a different topology, implying that this material does not satisfy a (pi, pi) nesting condition.

    View details for DOI 10.1103/PhysRevLett.103.076401

    View details for Web of Science ID 000269063300047

    View details for PubMedID 19792666

  • Quantum oscillations in the parent pnictide BaFe2As2: Itinerant electrons in the reconstructed state PHYSICAL REVIEW B Analytis, J. G., McDonald, R. D., Chu, J., Riggs, S. C., Bangura, A. F., Kucharczyk, C., Johannes, M., Fisher, I. R. 2009; 80 (6)
  • Asymmetric Quintuplet Condensation in the Frustrated S = 1 Spin Dimer Compound Ba3Mn2O8 PHYSICAL REVIEW LETTERS Samulon, E. C., Kohama, Y., McDonald, R. D., SHAPIRO, M. C., Al-Hassanieh, K. A., Batista, C. D., Jaime, M., Fisher, I. R. 2009; 103 (4)

    Abstract

    Ba_{3}Mn_{2}O_{8} is a spin-dimer compound based on pairs of S = 1, 3d;{2}, Mn;{5+} ions arranged on a triangular lattice. Antiferromagnetic intradimer exchange leads to a singlet ground state in zero field, with excited triplet and quintuplet states at higher energy. High field thermodynamic measurements are used to establish the phase diagram, revealing a substantial asymmetry of the quintuplet condensate. This striking effect, all but absent for the triplet condensate, is due to a fundamental asymmetry in quantum fluctuations of the paramagnetic phases near the various critical fields.

    View details for DOI 10.1103/PhysRevLett.103.047202

    View details for Web of Science ID 000268307400064

    View details for PubMedID 19659394

  • Experimental Realization of a Three-Dimensional Topological Insulator, Bi2Te3 SCIENCE Chen, Y. L., Analytis, J. G., Chu, J., Liu, Z. K., Mo, S., Qi, X. L., Zhang, H. J., Lu, D. H., Dai, X., Fang, Z., Zhang, S. C., Fisher, I. R., Hussain, Z., Shen, Z. 2009; 325 (5937): 178-181

    Abstract

    Three-dimensional topological insulators are a new state of quantum matter with a bulk gap and odd number of relativistic Dirac fermions on the surface. By investigating the surface state of Bi2Te3 with angle-resolved photoemission spectroscopy, we demonstrate that the surface state consists of a single nondegenerate Dirac cone. Furthermore, with appropriate hole doping, the Fermi level can be tuned to intersect only the surface states, indicating a full energy gap for the bulk states. Our results establish that Bi2Te3 is a simple model system for the three-dimensional topological insulator with a single Dirac cone on the surface. The large bulk gap of Bi2Te3 also points to promising potential for high-temperature spintronics applications.

    View details for DOI 10.1126/science.1173034

    View details for Web of Science ID 000267802000040

    View details for PubMedID 19520912

  • Topological Change of the Fermi Surface in Ternary Iron Pnictides with Reduced c/a Ratio: A de Haas-van Alphen Study of CaFe2P2 PHYSICAL REVIEW LETTERS Coldea, A. I., Andrew, C. M., Analytis, J. G., McDonald, R. D., Bangura, A. F., Chu, J., Fisher, I. R., Carrington, A. 2009; 103 (2)

    Abstract

    We report a de Haas-van Alphen effect study of the Fermi surface of CaFe2P2 using low-temperature torque magnetometry up to 45 T. This system is a close structural analog of the collapsed tetragonal nonmagnetic phase of CaFe2As2. We find the Fermi surface of CaFe2P2 to differ from other related ternary phosphides in that its topology is highly dispersive in the c axis, being three dimensional in character and with identical mass enhancement on both electron and hole pockets ( approximately 1.5). This suggests that when the bonding between pnictogen layers becomes important nesting conditions are not fulfilled.

    View details for DOI 10.1103/PhysRevLett.103.026404

    View details for Web of Science ID 000267887800041

    View details for PubMedID 19659226

  • Evidence for weak electronic correlations in iron pnictides PHYSICAL REVIEW B Yang, W. L., Sorini, A. P., Chen, C., Moritz, B., Lee, W., Vernay, F., Olalde-Velasco, P., Denlinger, J. D., Delley, B., Chu, J., Analytis, J. G., Fisher, I. R., Ren, Z. A., Yang, J., Lu, W., Zhao, Z. X., van den Brink, J., Hussain, Z., Shen, Z., Devereaux, T. P. 2009; 80 (1)
  • Electronic structure of the BaFe2As2 family of iron-pnictide superconductors PHYSICAL REVIEW B Yi, M., Lu, D. H., Analytis, J. G., Chu, J., Mo, S., He, R., Moore, R. G., Zhou, X. J., Chen, G. F., Luo, J. L., Wang, N. L., Hussain, Z., Singh, D. J., Fisher, I. R., Shen, Z. 2009; 80 (2)
  • Pressure-induced quenching of the charge-density-wave state in rare-earth tritellurides observed by x-ray diffraction PHYSICAL REVIEW B Sacchetti, A., Condron, C. L., Gvasaliya, S. N., Pfuner, F., Lavagnini, M., Baldini, M., Toney, M. F., Merlini, M., Hanfland, M., Mesot, J., Chu, J., Fisher, I. R., Postorino, P., Degiorgi, L. 2009; 79 (20)
  • Quantum oscillation studies of the Fermi surface of LaFePO PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS Carrington, A., Coldea, A. I., Fletcher, J. D., Hussey, N. E., Andrew, C. M., Bangura, A. F., Analytis, J. G., Chu, J., Erickson, A. S., Fisher, I. R., McDonald, R. D. 2009; 469 (9-12): 459-468
  • Pressure-Induced Superconducting Phase in the Charge-Density-Wave Compound Terbium Tritelluride PHYSICAL REVIEW LETTERS Hamlin, J. J., Zocco, D. A., Sayles, T. A., Maple, M. B., Chu, J., Fisher, I. R. 2009; 102 (17)

    Abstract

    A series of high-pressure electrical resistivity measurements on single crystals of TbTe3 reveal a complex phase diagram involving the interplay of superconducting, antiferromagnetic and charge-density-wave order. The onset of superconductivity reaches a maximum of almost 4 K (onset) near approximately 12.4 GPa.

    View details for DOI 10.1103/PhysRevLett.102.177002

    View details for Web of Science ID 000265948300052

    View details for PubMedID 19518815

  • ARPES studies of the electronic structure of LaOFe(P, As) PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS Lu, D. H., Yi, M., Mo, S., Analytis, J. G., Chu, J., Erickson, A. S., Singh, D. J., Hussain, Z., Geballe, T. H., Fisher, I. R., Shen, Z. 2009; 469 (9-12): 452-458
  • Evidence for a Nodal-Line Superconducting State in LaFePO PHYSICAL REVIEW LETTERS Fletcher, J. D., Serafin, A., Malone, L., Analytis, J. G., Chu, J., Erickson, A. S., Fisher, I. R., Carrington, A. 2009; 102 (14)

    Abstract

    In several iron-arsenide superconductors there is strong evidence for a fully gapped superconducting state consistent with either a conventional s-wave symmetry or an unusual s{+/-} state where the gap changes sign between the electron and hole Fermi-surface sheets. Here we report measurements of the penetration depth lambda(T) in very clean samples of the related iron-phosphide superconductor, LaFePO, at temperatures down to approximately 100 mK. We find that lambda(T) varies approximately linearly with T strongly suggesting the presence of gap nodes in this compound. Taken together with other data, this suggests the gap function is not universal for all pnictide superconductors.

    View details for DOI 10.1103/PhysRevLett.102.147001

    View details for Web of Science ID 000265082500058

    View details for PubMedID 19392472

  • High-pressure, transport, and thermodynamic properties of CeTe3 PHYSICAL REVIEW B Zocco, D. A., Hamlin, J. J., Sayles, T. A., Maple, M. B., Chu, J., Fisher, I. R. 2009; 79 (13)
  • Neutron scattering study of the interplay between structure and magnetism in Ba(Fe1-xCox)(2)As-2 PHYSICAL REVIEW B Lester, C., Chu, J., Analytis, J. G., Capelli, S. C., Erickson, A. S., Condron, C. L., Toney, M. F., Fisher, I. R., Hayden, S. M. 2009; 79 (14)
  • Optical properties of the charge-density-wave rare-earth tri-telluride compounds: A view on PrTe3 Pfuner, F., Degiorgi, L., Chu, J., Ru, N., Shin, K. Y., Fisher, I. R. ELSEVIER SCIENCE BV. 2009: 533-536
  • Fine Structure in the Electronic Density of States near the Fermi Energy of Al-Ni-Co Decagonal Quasicrystal from Ultrafast Time-Resolved Optical Reflectivity PHYSICAL REVIEW LETTERS Mertelj, T., Oslak, A., Dolinsek, J., Fisher, I. R., Kabanov, V. V., Mihailovic, D. 2009; 102 (8)

    Abstract

    We measured the temperature and fluence dependence of the time-resolved photoinduced optical reflectivity in a decagonal Al71.9Ni11.1Co17.0 quasicrystal. We find no evidence for the relaxation of a hot thermalized electron gas as observed in metals. Instead, a quick diffusion of the hot nonthermal carriers approximately 40 nm into the bulk is detected, enhanced by the presence of a broad pseudogap. From the relaxation dynamics we find evidence for the suppression of the electronic density of states (DOS) at the Fermi energy with respect to the electronic DOS at approximately 13 meV away from the Fermi energy which is consistent with recent theoretical calculations.

    View details for DOI 10.1103/PhysRevLett.102.086405

    View details for Web of Science ID 000263816200041

    View details for PubMedID 19257762

  • Pressure dependence of the single particle excitation in the charge-density-wave CeTe3 system PHYSICAL REVIEW B Lavagnini, M., Sacchetti, A., Marini, C., Valentini, M., Sopracase, R., Perucchi, A., Postorino, P., Lupi, S., Chu, J., Fisher, I. R., Degiorgi, L. 2009; 79 (7)
  • Charge dynamics of the spin-density-wave state in BaFe2As2 EUROPEAN PHYSICAL JOURNAL B Pfuner, F., Analytis, J. G., Chu, J., Fisher, I. R., Degiorgi, L. 2009; 67 (4): 513-517
  • Enhanced superconducting pairing interaction in indium-doped tin telluride PHYSICAL REVIEW B Erickson, A. S., Chu, J., Toney, M. F., Geballe, T. H., Fisher, I. R. 2009; 79 (2)
  • Determination of the phase diagram of the electron-doped superconductor Ba(Fe1-xCox)(2)As-2 PHYSICAL REVIEW B Chu, J., Analytis, J. G., Kucharczyk, C., Fisher, I. R. 2009; 79 (1)
  • Single-Particle and Collective Mode Couplings Associated with 1-and 2-Directional Electronic Ordering in Metallic RTe3 (R=Ho,Dy,Tb) PHYSICAL REVIEW LETTERS Yusupov, R. V., Mertelj, T., Chu, J., Fisher, I. R., Mihailovic, D. 2008; 101 (24)

    Abstract

    The coupling of phonons with collective modes and single-particle gap excitations associated with one- (1d) and two-directional (2d) electronically driven charge-density wave (CDW) ordering in metallic RTe3 is investigated as a function of rare-earth ion chemical pressure (R=Tb,Dy,Ho) using femtosecond pump-probe spectroscopy. From the T dependence of the CDW gap DeltaCDW and the amplitude mode, we find that while the transition to a 1d-CDW ordered state at Tc1 initially proceeds in an exemplary mean-field-like fashion, below Tc1, DeltaCDW is depressed and departs from the mean-field behavior. The effect is apparently triggered by resonant mode mixing of the amplitude mode with a totally symmetric phonon at 1.75 THz. At low temperatures, when the state evolves into a 2d-CDW ordered state at Tc2 in the DyTe3 and HoTe3, additional much weaker mode mixing is evident but no soft mode is observed.

    View details for DOI 10.1103/PhysRevLett.101.246402

    View details for Web of Science ID 000261704100039

    View details for PubMedID 19113640

  • Fermi Surface of Superconducting LaFePO Determined from Quantum Oscillations PHYSICAL REVIEW LETTERS Coldea, A. I., Fletcher, J. D., Carrington, A., Analytis, J. G., Bangura, A. F., Chu, J., Erickson, A. S., Fisher, I. R., Hussey, N. E., McDonald, R. D. 2008; 101 (21)

    Abstract

    We report extensive measurements of quantum oscillations in the normal state of the Fe-based superconductor LaFePO, (T(c) approximately 6 K) using low temperature torque magnetometry and transport in high static magnetic fields (45 T). We find that the Fermi surface is in broad agreement with the band-structure calculations with the quasiparticle mass enhanced by a factor approximately 2. The quasi-two-dimensional Fermi surface consists of nearly nested electron and hole pockets, suggesting proximity to a spin or charge density wave instability.

    View details for DOI 10.1103/PhysRevLett.101.216402

    View details for Web of Science ID 000261141500040

    View details for PubMedID 19113432

  • Evidence for coupling between charge density waves and phonons in two-dimensional rare-earth tritellurides PHYSICAL REVIEW B Lavagnini, M., Baldini, M., Sacchetti, A., Di Castro, D., Delley, B., Monnier, R., Chu, J., Ru, N., Fisher, I. R., Postorino, P., Degiorgi, L. 2008; 78 (20)
  • Transient electronic structure and melting of a charge density wave in TbTe3 SCIENCE Schmitt, F., Kirchmann, P. S., Bovensiepen, U., Moore, R. G., Rettig, L., Krenz, M., Chu, J., Ru, N., Perfetti, L., Lu, D. H., Wolf, M., Fisher, I. R., Shen, Z. 2008; 321 (5896): 1649-1652

    Abstract

    Obtaining insight into microscopic cooperative effects is a fascinating topic in condensed matter research because, through self-coordination and collectivity, they can lead to instabilities with macroscopic impacts like phase transitions. We used femtosecond time- and angle-resolved photoelectron spectroscopy (trARPES) to optically pump and probe TbTe3, an excellent model system with which to study these effects. We drove a transient charge density wave melting, excited collective vibrations in TbTe3, and observed them through their time-, frequency-, and momentum-dependent influence on the electronic structure. We were able to identify the role of the observed collective vibration in the transition and to document the transition in real time. The information that we demonstrate as being accessible with trARPES will greatly enhance the understanding of all materials exhibiting collective phenomena.

    View details for DOI 10.1126/science.1160778

    View details for Web of Science ID 000259300400026

    View details for PubMedID 18703710

  • Electronic structure of the iron-based superconductor LaOFeP NATURE Lu, D. H., Yi, M., Mo, S., Erickson, A. S., Analytis, J., Chu, J., Singh, D. J., Hussain, Z., Geballe, T. H., Fisher, I. R., Shen, Z. 2008; 455 (7209): 81-84

    Abstract

    The recent discovery of superconductivity in the iron oxypnictide family of compounds has generated intense interest. The layered crystal structure with transition-metal ions in planar square-lattice form and the discovery of spin-density-wave order near 130 K (refs 10, 11) seem to hint at a strong similarity with the copper oxide superconductors. An important current issue is the nature of the ground state of the parent compounds. Two distinct classes of theories, distinguished by the underlying band structure, have been put forward: a local-moment antiferromagnetic ground state in the strong-coupling approach, and an itinerant ground state in the weak-coupling approach. The first approach stresses on-site correlations, proximity to a Mott-insulating state and, thus, the resemblance to the high-transition-temperature copper oxides, whereas the second approach emphasizes the itinerant-electron physics and the interplay between the competing ferromagnetic and antiferromagnetic fluctuations. The debate over the two approaches is partly due to the lack of conclusive experimental information on the electronic structures. Here we report angle-resolved photoemission spectroscopy (ARPES) of LaOFeP (superconducting transition temperature, T(c) = 5.9 K), the first-reported iron-based superconductor. Our results favour the itinerant ground state, albeit with band renormalization. In addition, our data reveal important differences between these and copper-based superconductors.

    View details for DOI 10.1038/nature07263

    View details for Web of Science ID 000258890200040

    View details for PubMedID 18769435

  • de Haas-van Alphen oscillations in the charge density wave compound lanthanum tritelluride LaTe3 PHYSICAL REVIEW B Ru, N., Borzi, R. A., Rost, A., Mackenzie, A. P., Laverock, J., Dugdale, S. B., Fisher, I. R. 2008; 78 (4)
  • Magnetic properties of the charge density wave compounds RTe3 (R = Y, La, Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, Er, and Tm) PHYSICAL REVIEW B Ru, N., Chu, J., Fisher, I. R. 2008; 78 (1)
  • Singlet-triplet dispersion reveals additional frustration in the triangular-lattice dimer compound Ba3Mn2O8 PHYSICAL REVIEW LETTERS Stone, M. B., Lumsden, M. D., Chang, S., Samulon, E. C., Batista, C. D., Fisher, I. R. 2008; 100 (23)

    Abstract

    We present single crystal inelastic neutron scattering measurements of the S=1 dimerized quasi-two-dimensional antiferromagnet Ba(3)Mn(2)O(8). The singlet-triplet dispersion reveals nearest-neighbor and next-nearest-neighbor ferromagnetic interactions between adjacent bilayers that compete against each other. Although the interbilayer exchange is comparable to the intrabilayer exchange, this additional frustration reduces the effective coupling along the c axis and leads to a quasi-two-dimensional behavior. In addition, the obtained exchange values are able to reproduce the four critical fields in the phase diagram.

    View details for DOI 10.1103/PhysRevLett.100.237201

    View details for Web of Science ID 000256708100066

    View details for PubMedID 18643538

  • Angle-resolved photoemission study of the evolution of band structure and charge density wave properties in RTe3 (R=Y, La, Ce, Sm, Gd, Tb, and Dy) PHYSICAL REVIEW B Brouet, V., Yang, W. L., Zhou, X. J., Hussain, Z., Moore, R. G., He, R., Lu, D. H., Shen, Z. X., Laverock, J., Dugdale, S. B., Ru, N., Fisher, I. R. 2008; 77 (23)
  • Ordered magnetic phases of the frustrated spin-dimer compound Ba3Mn2O8 PHYSICAL REVIEW B Samulon, E. C., Jo, Y., Sengupta, P., Batista, C. D., Jaime, M., Balicas, L., Fisher, I. R. 2008; 77 (21)
  • Optical properties of the charge-density-wave polychalcogenide compounds R Te-2 (5) (R=Nd, Sm and Gd) EUROPEAN PHYSICAL JOURNAL B Pfuner, F., Degiorgi, L., Shin, K. Y., Fisher, I. R. 2008; 63 (1): 11-16
  • Charge density wave formation in R2Te5 (R=Nd, Sm, and Gd) PHYSICAL REVIEW B Shin, K. Y., Laverock, J., Wu, Y. Q., Condron, C. L., Toney, M. F., Dugdale, S. B., Kramer, M. J., Fisher, I. R. 2008; 77 (16)
  • Pressure dependence of the optical properties of the charge-density-wave compound LaTe2 PHYSICAL REVIEW B Lavagnini, M., Sacchetti, A., Degiorgi, L., Arcangeletti, E., Baldassarre, L., Postorino, P., Lupi, S., Perucchi, A., Shin, K. Y., Fisher, I. R. 2008; 77 (16)
  • Dispersive magnetic excitations in the S=1 antiferromagnet Ba3Mn2O8 PHYSICAL REVIEW B Stone, M. B., Lumsden, M. D., Qiu, Y., Samulon, E. C., Batista, C. D., Fisher, I. R. 2008; 77 (13)
  • Iron deposition on the tenfold surface of the Al72Ni11Co17 decagonal quasicrystal JOURNAL OF PHYSICS-CONDENSED MATTER Wearing, L. H., Smerdon, J. A., Leung, L., Dhesi, S. S., Ledieu, J., Bencok, P., Fisher, I., Jenks, C. J., McGrath, R. 2008; 20 (1)
  • Effect of chemical pressure on the charge density wave transition in rare-earth tritellurides RTe3 PHYSICAL REVIEW B Ru, N., Condron, C. L., Margulis, G. Y., Shin, K. Y., Laverock, J., Dugdale, S. B., Toney, M. F., Fisher, I. R. 2008; 77 (3)
  • Reply to "Comment on 'Extrinsic origin of the insulating behavior of polygrain icosahedral Al-Pd-Re quasicrystals' " PHYSICAL REVIEW B Dolinsek, J., McGuiness, P. J., Klanjsek, M., Smiljanic, I., Smontara, A., Zijlstra, E. S., Bose, S. K., Fisher, I. R., Kramer, M. J., Canfield, P. C. 2007; 76 (21)
  • STM studies of TbTe3: Evidence for a fully incommensurate charge density wave PHYSICAL REVIEW LETTERS Fang, A., Ru, N., Fisher, I. R., Kapitulnik, A. 2007; 99 (4)

    Abstract

    We observe unidirectional charge density wave (CDW) ordering on the quasi-2D material TbTe3 with a scanning tunneling microscope at approximately 6 K. Our analysis indicates that the CDW is fully incommensurate, with wave vector qCDW approximately 0.71x2pi/c. By imaging at various tip-sample voltages, we highlight effects of the subsurface layer and its effect on the CDW. We also observe an additional (possibly surface) dimerization and approximately 0.68x2pi/a ordering perpendicular to the CDW.

    View details for DOI 10.1103/PhysRevLett.99.046401

    View details for Web of Science ID 000248345800041

    View details for PubMedID 17678379

  • Ferromagnetism in the Mott insulator Ba2NaOsO6 PHYSICAL REVIEW LETTERS Erickson, A. S., Misra, S., Miller, G. J., Gupta, R. R., Schlesinger, Z., Harrison, W. A., Kim, J. M., Fisher, I. R. 2007; 99 (1)

    Abstract

    Results are presented of single crystal structural, thermodynamic, and reflectivity measurements of the double-perovskite Ba2NaOsO6. These characterize the material as a 5d1 ferromagnetic Mott insulator with an ordered moment of approximately 0.2microB per formula unit and TC=6.8(3) K. The magnetic entropy associated with this phase transition is close to Rln2, indicating that the quartet ground state anticipated from consideration of the crystal structure is split, consistent with a scenario in which the ferromagnetism is associated with orbital ordering.

    View details for DOI 10.1103/PhysRevLett.99.016404

    View details for Web of Science ID 000247819900034

    View details for PubMedID 17678173

  • Geometric frustration and dimensional reduction at a quantum critical point PHYSICAL REVIEW LETTERS Batista, C. D., Schmalian, J., Kawashima, N., Sengupta, P., Sebastian, S. E., Harrison, N., Jaime, M., Fisher, I. R. 2007; 98 (25)

    Abstract

    We show that the spatial dimensionality of the quantum critical point associated with Bose-Einstein condensation at T=0 is reduced when the underlying lattice comprises layers coupled by a frustrating interaction. Our theoretical predictions for the critical behavior correspond very well with recent measurements in BaCuSi(2)O(6) [ S. E. Sebastian et al., Nature (London) 441, 617 (2006)].

    View details for DOI 10.1103/PhysRevLett.98.257201

    View details for Web of Science ID 000247469400047

    View details for PubMedID 17678050

  • Optical properties of the Ce and La ditelluride charge density wave compounds PHYSICAL REVIEW B Lavagnini, M., Sacchetti, A., Degiorgi, L., Shin, K. Y., Fisher, I. R. 2007; 75 (20)
  • Pressure dependence of the charge-density-wave gap in rare-earth tritellurides PHYSICAL REVIEW LETTERS Sacchetti, A., Arcangeletti, E., Perucchi, A., Baldassarre, L., Postorino, P., Lupi, S., Ru, N., Fisher, I. R., Degiorgi, L. 2007; 98 (2)

    Abstract

    We investigate the pressure dependence of the optical properties of CeTe3, which exhibits an incommensurate charge-density-wave (CDW) state already at 300 K. Our data are collected in the midinfrared spectral range at room temperature and at pressures between 0 and 9 GPa. The energy for the single particle excitation across the CDW gap decreases upon increasing the applied pressure, similarly to the chemical pressure by rare-earth substitution. The broadening of the bands upon lattice compression removes the perfect nesting condition of the Fermi surface and therefore diminishes the impact of the CDW transition on the electronic properties of RTe3.

    View details for DOI 10.1103/PhysRevLett.98.026401

    View details for Web of Science ID 000243586700041

    View details for PubMedID 17358625

  • Multiple magnon modes and consequences for the Bose-Einstein condensed phase in BaCuSi2O6 PHYSICAL REVIEW LETTERS Ruegg, C., McMorrow, D. F., Normand, B., Ronnow, H. M., Sebastian, S. E., Fisher, I. R., Batista, C. D., Gvasaliya, S. N., Niedermayer, C., Stahn, J. 2007; 98 (1)

    Abstract

    The compound BaCuSi2O6 is a quantum magnet with antiferromagnetic dimers of S=1/2 moments on a quasi-2D square lattice. We have investigated its spin dynamics by inelastic neutron scattering experiments on single crystals with an energy resolution considerably higher than in an earlier study. We observe multiple magnon modes, indicating clearly the presence of magnetically inequivalent dimer sites. The more complex spin Hamiltonian revealed in our study leads to a distinct form of magnon Bose-Einstein condensate phase with a spatially modulated condensate amplitude.

    View details for DOI 10.1103/PhysRevLett.98.017202

    View details for Web of Science ID 000243379700045

    View details for PubMedID 17358501

  • Role of anisotropy in the spin-dimer compound BaCuSi2O6 PHYSICAL REVIEW B Sebastian, S. E., Tanedo, P., Goddard, P. A., Lee, S., Wilson, A., Kim, S., Cox, S., McDonald, R. D., Hill, S., Harrison, N., Batista, C. D., Fisher, I. R. 2006; 74 (18)
  • Extrinsic origin of the insulating behavior of polygrain icosahedral Al-Pd-Re quasicrystals PHYSICAL REVIEW B Dolinsek, J., McGuiness, P. J., Klanjsek, M., Smiljanic, I., Smontara, A., Zijlstra, E. S., Bose, S. K., Fisher, I. R., Kramer, M. J., Canfield, P. C. 2006; 74 (13)
  • Type II superconducting parameters of Tl-doped PbTe determined from heat capacity and electronic transport measurements PHYSICAL REVIEW B Matsushita, Y., Wianecki, P. A., Sommer, A. T., Geballe, T. H., Fisher, I. R. 2006; 74 (13)
  • Chemical pressure and hidden one-dimensional behavior in rare-earth tri-telluride charge-density wave compounds PHYSICAL REVIEW B Sacchetti, A., Degiorgi, L., Giamarchi, T., Ru, N., Fisher, I. R. 2006; 74 (12)
  • Dimensional reduction at a quantum critical point NATURE Sebastian, S. E., Harrison, N., Batista, C. D., Balicas, L., Jaime, M., Sharma, P. A., Kawashima, N., Fisher, I. R. 2006; 441 (7093): 617-620

    Abstract

    Competition between electronic ground states near a quantum critical point (QCP)--the location of a zero-temperature phase transition driven solely by quantum-mechanical fluctuations--is expected to lead to unconventional behaviour in low-dimensional systems. New electronic phases of matter have been predicted to occur in the vicinity of a QCP by two-dimensional theories, and explanations based on these ideas have been proposed for significant unsolved problems in condensed-matter physics, such as non-Fermi-liquid behaviour and high-temperature superconductivity. But the real materials to which these ideas have been applied are usually rendered three-dimensional by a finite electronic coupling between their component layers; a two-dimensional QCP has not been experimentally observed in any bulk three-dimensional system, and mechanisms for dimensional reduction have remained the subject of theoretical conjecture. Here we show evidence that the Bose-Einstein condensate of spin triplets in the three-dimensional Mott insulator BaCuSi2O6 (refs 12-16) provides an experimentally verifiable example of dimensional reduction at a QCP. The interplay of correlations on a geometrically frustrated lattice causes the individual two-dimensional layers of spin-(1/2) Cu2+ pairs (spin dimers) to become decoupled at the QCP, giving rise to a two-dimensional QCP characterized by linear power law scaling distinctly different from that of its three-dimensional counterpart. Thus the very notion of dimensionality can be said to acquire an 'emergent' nature: although the individual particles move on a three-dimensional lattice, their collective behaviour occurs in lower-dimensional space.

    View details for DOI 10.1038/nature04732

    View details for Web of Science ID 000237920800043

    View details for PubMedID 16738655

  • Comment on "Bose-Einstein condensation of magnons in Cs2CuCl4" PHYSICAL REVIEW LETTERS Sebastian, S. E., Zapf, V. S., Harrison, N., Batista, C. D., Sharma, P. A., Jaime, M., Fisher, I. R., Lacerda, A. 2006; 96 (18)
  • Use of periodic approximants in a dynamical LEED study of the quasicrystalline tenfold surface of decagonal Al-Ni-Co PHYSICAL REVIEW B Pussi, K., Ferralis, N., Mihalkovic, M., Widom, M., Curtarolo, S., Gierer, M., Jenks, C. J., Canfield, P., Fisher, I. R., Diehl, R. D. 2006; 73 (18)
  • Low-temperature structural phase transition and incommensurate lattice modulation in the spin-gap compound BaCuSi2O6 PHYSICAL REVIEW B Samulon, E. C., Islam, Z., Sebastian, S. E., Brooks, P. B., McCourt, M. K., Ilavsky, J., Fisher, I. R. 2006; 73 (10)
  • Thermodynamic and transport properties of YTe3, LaTe3, and CeTe3 PHYSICAL REVIEW B Ru, N., Fisher, I. R. 2006; 73 (3)
  • Bose-einstein condensation in BaCuSi2O6 YAMADA CONFERENCE LX ON RESEARCH IN HIGH MAGNETIC FIELDS Harrison, N., Sebastian, S. E., Batista, C. D., Jaime, M., Balicas, L., Sharma, P. A., Kawashima, N., Fisher, I. R. 2006; 51: 9-14
  • Scanning Hall probe imaging of ErNi2B2C PHYSICAL REVIEW B Bluhm, H., Sebastian, S. E., Guikema, J. W., Fisher, I. R., Moler, K. A. 2006; 73 (1)
  • Characteristic Bose-Einstein condensation scaling close to a quantum critical point in BaCuSi2O6 PHYSICAL REVIEW B Sebastian, S. E., Sharma, P. A., Jaime, M., Harrison, N., Correa, V., Balicas, L., Kawashima, N., Batista, C. D., Fisher, I. R. 2005; 72 (10)
  • Electronic structure and charge-density wave formation in LaTe1.95 and CeTe2.00 PHYSICAL REVIEW B Shin, K. Y., Brouet, V., Ru, N., Shen, Z. X., Fisher, I. R. 2005; 72 (8)
  • High-field behavior of the spin gap compound Sr2Cu(BO3)(2) PHYSICAL REVIEW B Sebastian, S. E., Yin, D., Tanedo, P., Jorge, G. A., Harrison, N., Jaime, M., Mozharivskyj, Y., Miller, G., Krzystek, J., Zvyagin, S. A., Fisher, I. R. 2005; 71 (21)
  • Magnetic structure of GdCo2Ge2 PHYSICAL REVIEW B Good, W., Kim, J., Goldman, A. I., Wermeille, D., Canfield, P. C., Cunningham, C., Islam, Z., Lang, J. C., Srajer, G., Fisher, I. R. 2005; 71 (22)
  • Evidence for charge Kondo effect in superconducting Tl-doped PbTe PHYSICAL REVIEW LETTERS Matsushita, Y., Bluhm, H., Geballe, T. H., Fisher, I. R. 2005; 94 (15)

    Abstract

    We report results of low-temperature thermodynamic and transport measurements of Pb1-xTlxTe single crystals for Tl concentrations up to the solubility limit of approximately x=1.5%. For all doped samples, we observe a low-temperature resistivity upturn that scales in magnitude with the Tl concentration. The temperature and field dependence of this upturn are consistent with a charge Kondo effect involving degenerate Tl valence states differing by two electrons, with a characteristic Kondo temperature T(K) approximately 6 K. The observation of such an effect supports an electronic pairing mechanism for superconductivity in this material and may account for the anomalously high T(c) values.

    View details for DOI 10.1103/PhysRevLett.94.157002

    View details for Web of Science ID 000228632500053

    View details for PubMedID 15904175

  • Fermi surface nesting and charge-density wave formation in rare-earth tritellurides PHYSICAL REVIEW B Laverock, J., Dugdale, S. B., Major, Z., Alam, M. A., Ru, N., Fisher, I. R., Santi, G., Bruno, E. 2005; 71 (8)
  • Magneto-optic spectrum and electronic structure of single-crystal MnBi JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS Brammeier, D. P., Park, J. M., Olson, C. G., Fisher, I. R., Lynch, D. W. 2004; 283 (1): 95-102
  • An STM and SXPS study of the interaction of C-60 with the ten-fold surface of the Al72Ni11Co17 quasicrystal SURFACE SCIENCE Cox, E. J., Ledieu, J., Dhanak, V. R., Barrett, S. D., Jenks, C. J., Fisher, I., McGrath, R. 2004; 566: 1200-1205
  • Fermi surface reconstruction in the CDW state of CeTe3 observed by photoemission PHYSICAL REVIEW LETTERS Brouet, V., Yang, W. L., Zhou, X. J., Hussain, Z., Ru, N., Shin, K. Y., Fisher, I. R., Shen, Z. X. 2004; 93 (12)

    Abstract

    CeTe3 is a layered compound where an incommensurate charge density wave (CDW) opens a large gap ( approximately 400 meV) in optimally nested regions of the Fermi surface (FS), whereas other sections with poorer nesting remain ungapped. Through angle-resolved photoemission, we identify bands backfolded according to the CDW periodicity. They define FS pockets formed by the intersection of the original FS and its CDW replica. Such pockets illustrate very directly the role of nesting in the CDW formation but they could not be detected so far in a CDW system. We address the reasons for the weak intensity of the folded bands, by comparing different foldings coexisting in CeTe3.

    View details for DOI 10.1103/PhysRevLett.93.126405

    View details for Web of Science ID 000223923800059

    View details for PubMedID 15447291

  • Magnetic properties of single grain r-mg-cd primitive icosahedral quasicrystals (R = Y, Gd, Tb or Dy) PHILOSOPHICAL MAGAZINE Sebastian, S. E., Huie, T., Fisher, I. R., Dennis, K. W., Kramer, M. J. 2004; 84 (10): 1029-1037
  • Structure of the tenfold d-Al-Ni-Co quasicrystal surface PHYSICAL REVIEW B Ferralis, N., Pussi, K., Cox, E. J., Gierer, M., Ledieu, J., Fisher, I. R., Jenks, C. J., Lindroos, M., McGrath, R., Diehl, R. D. 2004; 69 (15)
  • Phonon dispersion curve of icosahedral Mg-Zn-Y quasicrystals Brand, R. A., Voss, J., Hippert, F., Krisch, M., Sterzel, R., Assmus, W., Fisher, I. R. ELSEVIER SCIENCE BV. 2004: 207-209
  • Low-energy electron diffraction study of Xe adsorption on the ten-fold decagonal Al-Ni-Co quasicrystal surface PHYSICAL REVIEW B Ferralis, N., Diehl, R. D., Pussi, K., Lindroos, M., Fisher, I., Jenks, C. J. 2004; 69 (7)
  • Degree of structural perfection of icosahedral quasicrystalline grains investigated by synchrotron X-ray diffractometry and imaging techniques PHILOSOPHICAL MAGAZINE Gastaldi, J., Agliozzo, S., Letoublon, A., Wang, J., Mancini, L., Klein, H., Hartwig, J., Baruchel, J., Fisher, I. R., Sato, T., Tsai, A. P., de Boissieu, A. M. 2003; 83 (1): 1-29
  • Surface structures of approximant phases in the Al-Pd-Mn system PHYSICAL REVIEW B Fournee, V., Ross, A. R., Lograsso, T. A., Anderegg, J. W., Dong, C., Kramer, M., Fisher, I. R., Canfield, P. C., Thiel, P. A. 2002; 66 (16)
  • Transport properties of icosahedral quasicrystal Al72Pd19.5Mn8.5 JOURNAL OF ALLOYS AND COMPOUNDS Bilusic, A., Budrovic, Z., Smontara, A., Dolinsek, J., Canfield, P. C., Fisher, I. R. 2002; 342 (1-2): 413-415
  • Quasicrystal surfaces: potential as templates for molecular adsorption JOURNAL OF ALLOYS AND COMPOUNDS McGrath, R., Ledieu, J., Cox, E. J., Haq, S., Diehl, R. D., Jenks, C. J., Fisher, I., Ross, A. R., Lograsso, T. A. 2002; 342 (1-2): 432-436
  • The local atomic structure of R-Mg-Zn (R=Y, Gd, Dy and Tb) JOURNAL OF ALLOYS AND COMPOUNDS Kramer, M. J., Hong, S. T., Canfield, P. C., Fisher, I. R., Corbett, J. D., Zhu, Y., Goldman, A. I. 2002; 342 (1-2): 82-86
  • The electrical conductivity of single-grain Al-Pd-Re quasicrystals PHILOSOPHICAL MAGAZINE B-PHYSICS OF CONDENSED MATTER STATISTICAL MECHANICS ELECTRONIC OPTICAL AND MAGNETIC PROPERTIES Fisher, I. R., Xie, X. P., Tudosa, I., Gao, C. W., Song, C., Canfield, P. C., Kracher, A., Dennis, K., Abanoz, D., Kramer, M. J. 2002; 82 (9): 1089-1098
  • Surface preparation and characterization of the icosahedral Al-Ga-Pd-Mn quasicrystal JOURNAL OF ALLOYS AND COMPOUNDS Heinzig, M., Jenks, C. J., Van Hove, M., Fisher, I., Canfield, P. C., Thiel, P. A. 2002; 338 (1-2): 248-252
  • Icosahedral quasicrystal Al71Pd21Mn08 and its xi ' approximant: Linear expansivity, specific heat, magnetic susceptibility, electrical resistivity, and elastic constants PHYSICAL REVIEW B Swenson, C. A., Fisher, I. R., Anderson, N. E., Canfield, P. C., Migliori, A. 2002; 65 (18)
  • Infrared and optical properties of pure and cobalt-doped LuNi2B2C PHYSICAL REVIEW B Windt, M., McGuire, J. J., Room, T., Pronin, A., Timusk, T., Fisher, I. R., Canfield, P. C. 2002; 65 (6)
  • Microwave conductivity and penetration depth in the heavy fermion superconductor CeCoIn5 PHYSICAL REVIEW LETTERS Ormeno, R. J., Sibley, A., Gough, C. E., Sebastian, S., Fisher, I. R. 2002; 88 (4)

    Abstract

    The electrodynamic properties of the quasi-two-dimensional heavy fermion superconductor CeCoIn5 have been investigated by microwave surface impedance measurements over a wide range of microwave frequencies and temperatures. We derive a value penetration depth lambda(0) approximately 190 nm, with a strong linear term in the temperature dependence of lambda(T) below T(c)/3, consistent with a superconducting gap with line nodes. The real part of the conductivity displays a broad peak at low temperatures consistent with a decreased scattering rate of almost 2 orders of magnitude below T(c). CeCoIn5 has remarkably similar properties to those of the high-T(c) cuprates.

    View details for DOI 10.1103/PhysRevLett.88.047005

    View details for Web of Science ID 000173907500066

    View details for PubMedID 11801159

  • Unusual spin-glass phase in icosahedral Tb-Mg-Zn quasicrystals PHYSICAL REVIEW B Dolinsek, J., Jaglicic, Z., Chernikov, M. A., Fisher, I. R., Canfield, P. C. 2001; 64 (22)
  • Observation of a spin reorientation in TbCu2Ge2 from resonant and nonresonant x-ray scattering PHYSICAL REVIEW B Song, C., Johnson, D., Wermeille, D., Goldman, A. I., Bud'ko, S. L., Fisher, I. R., Canfield, P. C. 2001; 64 (22)
  • Reentrant behavior in the temperature dependence of metamagnetic transitions in single crystal Nd6Fe13-xAl1+x IEEE TRANSACTIONS ON MAGNETICS McCallum, R. W., Fisher, I. R., Anderson, N. E., Canfield, P. C., Kramer, M. J., Dennis, K. W. 2001; 37 (4): 2147-2149
  • High-temperature solution growth of intermetallic single crystals and quasicrystals JOURNAL OF CRYSTAL GROWTH Canfield, P. C., Fisher, I. R. 2001; 225 (2-4): 155-161
  • R9Mg34Zn57 icosahedral quasicrystals: The tuning of a model spin glass JOURNAL OF ALLOYS AND COMPOUNDS Canfield, P. C., Fisher, I. R. 2001; 317: 443-447
  • Structure and physical properties of the new pseudo-binary intermetallic compound Ti-11(Sb, Sn)(8) JOURNAL OF SOLID STATE CHEMISTRY Kim, H., Olmstead, M. M., Chan, J. Y., Canfield, P. C., Fisher, I. R., Henning, R. W., Schultz, A. J., Kauzlarich, S. M. 2001; 157 (1): 225-232
  • Growth of large single-grain quasicrystals from high-temperature metallic solutions Fisher, I. R., Kramer, M. J., Islam, Z., Wiener, T. A., Kracher, A., Ross, A. R., Lograsso, T. A., Goldman, A. I., Canfield, P. C. ELSEVIER SCIENCE SA. 2000: 10-16
  • Plasticity of icosahedral Zn-Mg-Dy single quasicrystals MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING Heggen, M., Feuerbacher, M., Schall, P., Klein, H., Fisher, I. R., Canfield, P. C., Urban, K. 2000; 294: 781-785
  • Formation and morphological development of porosity in icosahedral Al-Pd-Mn alloys MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING Ross, A. R., Wiener, T. A., Fisher, I. R., Canfield, P. C., Lograsso, T. A. 2000; 294: 53-56
  • Electrical resistivity, thermopower, and thermal conductivity of single grained (Y, Tb, Ho, Er)-Mg-Zn icosahedral quasicrystals MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING Gianno, K., Sologubenko, A. V., Chernikov, M. A., Ott, H. R., Fisher, I. R., Canfield, P. C. 2000; 294: 715-718
  • Heat capacities of icosahedral and hexagonal phases of Zn-Mg-Y system MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING Inaba, A., Takakura, H., Tsai, A. P., Fisher, I. R., Canfield, P. C. 2000; 294: 723-726
  • Phason strain and structural perfection in the Zn-Mg-rare-earth icosahedral phases MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING Letoublon, A., Fisher, I. R., Sato, T. J., de Boissieu, M., Boudard, M., Agliozzo, S., Mancini, L., Gastaldi, J., Canfield, P. C., Goldman, A. I., Tsai, A. P. 2000; 294: 127-130
  • Diffusion of Co-57 in decagonal Al-Ni-Co-quasicrystals MATERIALS SCIENCE AND ENGINEERING A-STRUCTURAL MATERIALS PROPERTIES MICROSTRUCTURE AND PROCESSING Khoukaz, C., Galler, R., Mehrer, H., Canfield, P. C., Fisher, I. R., Feuerbacher, M. 2000; 294: 697-701
  • Design of a metallic Ising spin glass in the Y1-xTbxNi2Ge2 system PHYSICAL REVIEW B Wiener, T. A., Fisher, I. R., Bud'ko, S. L., Kracher, A., Canfield, P. C. 2000; 62 (22): 15056-15066
  • Electronic structure of quasicrystalline surfaces: Effects of surface preparation and bulk structure PHYSICAL REVIEW B Fournee, V., Pinhero, P. J., Anderegg, J. W., Lograsso, T. A., Ross, A. R., Canfield, P. C., Fisher, I. R., Thiel, P. A. 2000; 62 (21): 14049-14060
  • Unconventional electronic Raman spectra of borocarbide superconductors PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS Yang, I. S., Klein, M. V., Devereaux, T. P., Fisher, I. R., Canfield, P. C. 2000; 341: 2259-2260
  • Recent advances in the study of quasicrystals MICRON Fisher, I. R., Kramer, M. J., Goldman, A. I. 2000; 31 (5): 469-473
  • Nonlocal effects in magnetization of high-kappa superconductors PHYSICAL REVIEW B Kogan, V. G., Bud'ko, S. L., Fisher, I. R., Canfield, P. C. 2000; 62 (13): 9077-9082
  • Observation of a metamagnetic phase transition in an itinerant 4f system via the magneto-optic Kerr effect: Ce(Fe1-xCox)(2) PHYSICAL REVIEW B Lange, R. J., Fisher, I. R., Canfield, P. C., Antropov, V. P., Lee, S. J., Harmon, B. N., Lynch, D. W. 2000; 62 (11): 7084-7092
  • Yb14ZnSb11: Charge balance in Zintl compounds as a route to intermediate Yb valence PHYSICAL REVIEW LETTERS Fisher, I. R., Bud'ko, S. L., Song, C., Canfield, P. C., Ozawa, T. C., Kauzlarich, S. M. 2000; 85 (5): 1120-1123
  • Low-temperature thermal conductivity of a single-grain Y-Mg-Zn icosahedral quasicrystal PHYSICAL REVIEW B Gianno, K., Sologubenko, A. V., Chernikov, M. A., Ott, H. R., Fisher, I. R., Canfield, P. C. 2000; 62 (1): 292-300
  • Low-temperature transport, thermal, and optical properties of single-grain quasicrystals of icosahedral phases in the Y-Mg-Zn and Tb-Mg-Zn alloy systems PHYSICAL REVIEW B Chernikov, M. A., Paschen, S., Felder, E., Vorburger, P., Ruzicka, B., Degiorgi, L., Ott, H. R., Fisher, I. R., Canfield, P. C. 2000; 62 (1): 262-272
  • The magnetic characteristics of the Tb(Ni1-xCox)(2)Ge-2 system JOURNAL OF ALLOYS AND COMPOUNDS Wiener, T. A., Fisher, I. R., Canfield, P. C. 2000; 303: 289-292
  • Magnetic properties of icosahedral R-Mg-Zn quasicrystals (R=Y, Tb, Dy, Ho and Er) JOURNAL OF ALLOYS AND COMPOUNDS Fisher, I. R., Islam, Z., Zarestky, J., Stassis, C., Kramer, M. J., Goldman, A. I., Canfield, P. C. 2000; 303: 223-227
  • Non-locality and the flux line lattice square to hexagonal symmetry transition in the borocarbide superconductors PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS Eskildsen, M. R., Fisher, I. R., Gammel, P. L., Bishop, D. J., Andersen, N. H., Mortensen, K., Canfield, P. C. 2000; 332 (1-4): 320-326
  • Interwoven magnetic and flux line structures in single crystal (Tm,Er)Ni2B2C (invited) JOURNAL OF APPLIED PHYSICS Gammel, P. L., Lopez, D., Bishop, D. J., Eskildsen, M. R., Andersen, N. H., Mortensen, K., Fisher, I. R., Cheon, K. O., Canfield, P. C. 2000; 87 (9): 5544-5548
  • Optical properties and electronic structure of single crystals of EuAl2 and YbAl2 PHYSICAL REVIEW B Lee, S. J., Hong, S. Y., Fisher, I. R., Canfield, P. C., Harmon, B. N., Lynch, D. W. 2000; 61 (15): 10076-10083
  • A LEED comparison of structural stabilities of the three high-symmetry surfaces of Al-Pd-Mn bulk quasicrystals SURFACE SCIENCE Shen, Z., Raberg, W., Heinzig, M., Jenks, C. J., Fournee, V., Van Hove, M. A., Lograsso, T. A., Delaney, D., Cai, T., Canfield, P. C., Fisher, I. R., Goldman, A. I., Kramer, M. J., Thiel, P. A. 2000; 450 (1-2): 1-11
  • Plastic deformation of icosahedral Zn-Mg-Dy single quasicrystals PHILOSOPHICAL MAGAZINE LETTERS Heggen, M., Feuerbacher, M., Schall, P., Klein, H., Fisher, I. R., Canfield, P. C., Urban, K. 2000; 80 (3): 129-136
  • Flux line lattice symmetries in the borocarbide superconductors MAGNETIC AND SUPERCONDUCTING MATERIALS, (MSM-99), VOLS A AND B Eskildsen, M. R., Gammel, P. L., Bishop, D. J., Andersen, N. H., Mortensen, K., Fisher, I. R., Canfield, P. C. 2000: 433-446
  • Nesting properties and anisotropy of the Fermi surface of LuNi2B2C PHYSICAL REVIEW LETTERS Dugdale, S. B., Alam, M. A., Wilkinson, I., Hughes, R. J., Fisher, I. R., Canfield, P. C., Jarlborg, T., Santi, G. 1999; 83 (23): 4824-4827
  • Anisotropy and metamagnetism in the RNi2Ge2 (R = Y, La-Nd, Sm-Lu) series JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS Bud'ko, S. L., Islam, Z., Wiener, T. A., Fisher, I. R., Lacerda, A. H., Canfield, P. C. 1999; 205 (1): 53-78
  • Systematic study of anisotropic transport and magnetic properties of RAgSb2 (R = Y, La-Nd, Sm, Gd-Tm) JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS Myers, K. D., Bud'ko, S. L., Fisher, I. R., Islam, Z., Kleinke, H., Lacerda, A. H., Canfield, P. C. 1999; 205 (1): 27-52
  • On the growth of icosahedral Al-Pd-Mn quasicrystals from the ternary melt PHILOSOPHICAL MAGAZINE B-PHYSICS OF CONDENSED MATTER STATISTICAL MECHANICS ELECTRONIC OPTICAL AND MAGNETIC PROPERTIES Fisher, I. R., Kramer, M. J., Wiener, T. A., Islam, Z., Ross, A. R., Lograsso, T. A., Kracher, A., Goldman, A. I., Canfield, P. C. 1999; 79 (10): 1673-1684
  • Critical doping in overdoped high-T-c superconductors: a quantum critical point? PHYSICA STATUS SOLIDI B-BASIC SOLID STATE PHYSICS Tallon, J. L., Loram, J. W., Williams, G. V., Cooper, J. R., Fisher, I. R., Johnson, J. D., Staines, M. P., Bernhard, C. 1999; 215 (1): 531-540
  • Magnetic and transport properties of single-crystal R2Cu2In (R = Gd-Tm, Lu) JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS Fisher, I. R., Islam, Z., Canfield, P. C. 1999; 202 (1): 1-10
  • Thermodynamic and transport properties of single-crystal Yb14MnSb11 PHYSICAL REVIEW B Fisher, I. R., Wiener, T. A., Bud'ko, S. L., Canfield, P. C., Chan, J. Y., Kauzlarich, S. M. 1999; 59 (21): 13829-13834
  • Systematic studies of the square-hexagonal flux line lattice transition in Lu(Ni1-xCox)(2)B2C: The role of nonlocality PHYSICAL REVIEW LETTERS Gammel, P. L., Bishop, D. J., Eskildsen, M. R., Mortensen, K., Andsersen, N. H., Fisher, I. R., Cheon, K. O., Canfield, P. C., Kogan, V. G. 1999; 82 (20): 4082-4085
  • On the growth of decagonal Al-Ni-Co quasicrystals from the ternary melt PHILOSOPHICAL MAGAZINE B-PHYSICS OF CONDENSED MATTER STATISTICAL MECHANICS ELECTRONIC OPTICAL AND MAGNETIC PROPERTIES Fisher, I. R., Kramer, M. J., Islam, Z., Ross, A. R., Kracher, A., Wiener, T., Sailer, M. J., Goldman, A. I., Canfield, P. C. 1999; 79 (3): 425-434
  • Boron isotope effect in single-crystal YNi2B2C and LuNi2B2C superconductors PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS Cheon, K. O., Fisher, I. R., Canfield, P. C. 1999; 312 (1-2): 35-39
  • Magnetic and transport properties of single-grain R-Mg-Zn icosahedral quasicrystals [R = Y, (Y1-xGdx), (Y1-xTbx), Tb, Dy, Ho, and Er] PHYSICAL REVIEW B Fisher, I. R., Cheon, K. O., Panchula, A. F., Canfield, P. C., Chernikov, M., Ott, H. R., Dennis, K. 1999; 59 (1): 308-321
  • Resistivity and magnetic susceptibility of single-crystal Lu(Ni1-xCox)(2)B2C (x=0.0-0.09) PHYSICAL REVIEW B Cheon, K. O., Fisher, I. R., Kogan, V. G., Canfield, P. C., Miranovic, P., Gammel, P. L. 1998; 58 (10): 6463-6467
  • Growth of large-grain R-Mg-Zn quasicrystals from the ternary melt (R = Y, Er, Ho, Dy, Tb) PHILOSOPHICAL MAGAZINE B-PHYSICS OF CONDENSED MATTER STATISTICAL MECHANICS ELECTRONIC OPTICAL AND MAGNETIC PROPERTIES Fisher, I. R., Islam, Z., Panchula, A. F., Cheon, K. O., Kramer, M. J., Canfield, P. C., Goldman, A. I. 1998; 77 (6): 1601-1615
  • Reinvestigation of long-range magnetic ordering in icosahedral Tb-Mg-Zn PHYSICAL REVIEW B Islam, Z., Fisher, I. R., Zarestky, J., Canfield, P. C., Stassis, C., Goldman, A. I. 1998; 57 (18): R11047-R11050
  • Electrical Resistivity of Iodine-Intercalated Bi2Sr2CaCu2O8 Subjected to a Magnetic Field MOLECULAR CRYSTALS AND LIQUID CRYSTALS SCIENCE AND TECHNOLOGY SECTION A-MOLECULAR CRYSTALS AND LIQUID CRYSTALS Ghorayeb, A. M., Monnereau, O., Fermond, L., Badeche, T., Hussey, N. E., Dewhurst, C. D., Fisher, I. R., Seow, W. S., Doyle, R. A. 1998; 311: 435-442
  • Anisotropic resistivity and normal-state magnetoresistance of RNi2B2C (R = Y, Lu, Er, Ho) PHYSICAL REVIEW B Fisher, I. R., Cooper, J. R., Canfield, P. C. 1997; 56 (17): 10820-10823
  • Normal-state properties of RNi(2)B(2)C (R=Y,Ho,La) and anisotropic resistivity of single-crystal RNi(2)B(2)C (R=Lu, Pr, Ho) JOURNAL OF LOW TEMPERATURE PHYSICS Fisher, I. R., Cooper, J. R., Locherer, K. R., Cava, R. J., Canfield, P. C. 1996; 105 (5-6): 1623-1628
  • Effect of sample density on the resistivity and Hall coefficient of polycrystalline La1.83Sr0.17CuO4 PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS Fisher, I. R., Cooper, J. R. 1996; 272 (1-2): 125-130
  • Angular dependence of the c-axis normal state magnetoresistance in single crystal Tl2Ba2CuO6 PHYSICAL REVIEW LETTERS Hussey, N. E., Cooper, J. R., Wheatley, J. M., Fisher, I. R., Carrington, A., Mackenzie, A. P., Lin, C. T., Milat, O. 1996; 76 (1): 122-125
  • HALL-EFFECT AND THERMOELECTRIC-POWER MEASUREMENTS ON Y0.9CA0.1BA2CU3O7-DELTA PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS Fisher, I. R., DESILVA, P. S., Loram, J. W., Tallon, J. L., Carrington, A., Cooper, J. R. 1994; 235: 1497-1498