Academic Appointments


Administrative Appointments


  • Chief Scientist, SLAC (2010 - 2013)
  • Director, Stanford Institute for Materials and Energy Sciences (2006 - 2011)
  • Director, Geballe Laboratory For Advanced Materials (2005 - 2008)

Honors & Awards


  • Honorary Professorship, Nanjing University (2014)
  • Einstein Professorship, Chinese Academy of Sciences (2013)
  • Oliver Buckley Condensed Matter Physics Prize, American Physical Society (2011)
  • Ernest Olando Lawrence Award, US Department of Energy (2010)
  • Paul Pigott Professor in Physical Science, Stanford University (2006)
  • Fellow, American Physical Society (2002)
  • The Takeda Techno-Entrepreneurship Award, The Takeda Foundation, Japan (2002)
  • H. Kamerlingh Onnes Prize, Conference on Materials and Mechanism of superconductivity (2000)
  • Centennial Cerebration Lecture, American Physical Society (1999)
  • Outstanding Scientific Accomplishment Award, Office of Basic Energy Sciences, Department of Energy (1994)
  • Fellow, Alfred P. Sloan Foundation (1993)

Current Research and Scholarly Interests


Dr. Shen's main research interest lies in the area of condensed matter and materials physics, as well as the applications of materials and devices. He develops photon based innovative instrumentation and advanced experimental techniques, ranging from angle-resolved photoemission to microwave imaging, soft x-ray scattering and time domain spectroscopy and scattering. He has created a body of literature that advanced our understanding of quantum materials, including superconductors, semiconductors, novel magnets, topological insulators, novel carbon and electron emitters. He is best known for his discoveries of the momentum structure of anisotropic d-wave pairing gap and anomalous normal state pseudogap in high temperature superconductors. He has further leveraged the advanced characterization tool to make better materials through thin film and interface engineering.

Journal Articles


  • Direct spectroscopic evidence for phase competition between the pseudogap and superconductivity in Bi2Sr2CaCu2O8+delta NATURE MATERIALS Hashimoto, M., Nowadnick, E. A., He, R., Vishik, I. M., Moritz, B., He, Y., Tanaka, K., Moore, R. G., Lu, D., Yoshida, Y., Ishikado, M., Sasagawa, T., Fujita, K., Ishida, S., Uchida, S., Eisaki, H., Hussain, Z., Devereaux, T. P., Shen, Z. 2015; 14 (1): 37-42

    Abstract

    In the high-temperature (Tc) cuprate superconductors, a growing body of evidence suggests that the pseudogap phase, existing below the pseudogap temperature T(∗), is characterized by some broken electronic symmetries distinct from those associated with superconductivity. In particular, recent scattering experiments have suggested that charge ordering competes with superconductivity. However, no direct link of an interplay between the two phases has been identified from the important low-energy excitations. Here, we report an antagonistic singularity at Tc in the spectral weight of Bi2Sr2CaCu2O8+δ as compelling evidence for phase competition, which persists up to a high hole concentration p ~ 0.22. Comparison with theoretical calculations confirms that the singularity is a signature of competition between the order parameters for the pseudogap and superconductivity. The observation of the spectroscopic singularity at finite temperatures over a wide doping range provides new insights into the nature of the competitive interplay between the two orders and the complex phase diagram near the pseudogap critical point.

    View details for DOI 10.1038/NMAT4116

    View details for Web of Science ID 000346430100011

    View details for PubMedID 25362356

  • Giant bandgap renormalization and excitonic effects in a monolayer transition metal dichalcogenide semiconductor NATURE MATERIALS Ugeda, M. M., Bradley, A. J., Shi, S., da Jornada, F. H., Zhang, Y., Qiu, D. Y., Ruan, W., Mo, S., Hussain, Z., Shen, Z., Wang, F., Louie, S. G., Crommie, M. F. 2014; 13 (12): 1091-1095

    View details for DOI 10.1038/NMAT4061

    View details for Web of Science ID 000345432200009

  • Molecular beam epitaxial growth of a three-dimensional topological Dirac semimetal Na3Bi APPLIED PHYSICS LETTERS Zhang, Y., Liu, Z., Zhou, B., Kim, Y., Hussain, Z., Shen, Z., Chen, Y., Mo, S. 2014; 105 (3)

    View details for DOI 10.1063/1.4890940

    View details for Web of Science ID 000341152300021

  • Energy gaps in high-transition-temperature cuprate superconductors NATURE PHYSICS Hashimoto, M., Vishik, I. M., He, R., Devereaux, T. P., Shen, Z. 2014; 10 (7): 483-495

    View details for DOI 10.1038/NPHYS3009

    View details for Web of Science ID 000338843100014

  • Shielded piezoresistive cantilever probes for nanoscale topography and electrical imaging JOURNAL OF MICROMECHANICS AND MICROENGINEERING Yang, Y., Ma, E. Y., Cui, Y., Haemmerli, A., Lai, K., Kundhikanjana, W., Harjee, N., Pruitt, B. L., Kelly, M., Shen, Z. 2014; 24 (4)
  • Direct observation of the transition from indirect to direct bandgap in atomically thin epitaxial MoSe2 NATURE NANOTECHNOLOGY Zhang, Y., Chang, T., Zhou, B., Cui, Y., Yan, H., Liu, Z., Schmitt, F., Lee, J., Moore, R., Chen, Y., Lin, H., Jeng, H., Mo, S., Hussain, Z., Bansil, A., Shen, Z. 2014; 9 (2): 111-115

    Abstract

    Quantum systems in confined geometries are host to novel physical phenomena. Examples include quantum Hall systems in semiconductors and Dirac electrons in graphene. Interest in such systems has also been intensified by the recent discovery of a large enhancement in photoluminescence quantum efficiency and a potential route to valleytronics in atomically thin layers of transition metal dichalcogenides, MX2 (M = Mo, W; X = S, Se, Te), which are closely related to the indirect-to-direct bandgap transition in monolayers. Here, we report the first direct observation of the transition from indirect to direct bandgap in monolayer samples by using angle-resolved photoemission spectroscopy on high-quality thin films of MoSe2 with variable thickness, grown by molecular beam epitaxy. The band structure measured experimentally indicates a stronger tendency of monolayer MoSe2 towards a direct bandgap, as well as a larger gap size, than theoretically predicted. Moreover, our finding of a significant spin-splitting of ∼180 meV at the valence band maximum of a monolayer MoSe2 film could expand its possible application to spintronic devices.

    View details for DOI 10.1038/NNANO.2013.277

    View details for Web of Science ID 000331069200012

    View details for PubMedID 24362235

  • Examining Electron-Boson Coupling Using Time-Resolved Spectroscopy PHYSICAL REVIEW X Sentef, M., Kemper, A. F., Moritz, B., Freericks, J. K., Shen, Z., Devereaux, T. P. 2013; 3 (4)
  • Covalent Attachment of Diamondoid Phosphonic Acid Dichlorides to Tungsten Oxide Surfaces LANGMUIR Li, F. H., Fabbri, J. D., Yurchenko, R. I., Mileshkin, A. N., Hohman, J. N., Yan, H., Yuan, H., Tran, I. C., Willey, T. M., Bagge-Hansen, M., Dahl, J. E., Carlson, R. M., Fokin, A. A., Schreiner, P. R., Shen, Z., Melosh, N. A. 2013; 29 (31): 9790-9797

    Abstract

    Diamondoids (nanometer-sized diamond-like hydrocarbons) are a novel class of carbon nanomaterials that exhibit negative electron affinity (NEA) and strong electron-phonon scattering. Surface-bound diamondoid monolayers exhibit monochromatic photoemission, a unique property that makes them ideal electron sources for electron-beam lithography and high-resolution electron microscopy. However, these applications are limited by the stability of the chemical bonding of diamondoids on surfaces. Here we demonstrate the stable covalent attachment of diamantane phosphonic dichloride on tungsten/tungsten oxide surfaces. X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared (FTIR) spectroscopy revealed that diamondoid-functionalized tungsten oxide films were stable up to 300-350 °C, a substantial improvement over conventional diamondoid thiolate monolayers on gold, which dissociate at 100-200 °C. Extreme ultraviolet (EUV) light stimulated photoemission from these diamondoid phosphonate monolayers exhibited a characteristic monochromatic NEA peak with 0.2 eV full width at half-maximum (fwhm) at room temperature, showing that the unique monochromatization property of diamondoids remained intact after attachment. Our results demonstrate that phosphonic dichloride functionality is a promising approach for forming stable diamondoid monolayers for elevated temperature and high-current applications such as electron emission and coatings in micro/nano electromechanical systems (MEMS/NEMS).

    View details for DOI 10.1021/la401781e

    View details for Web of Science ID 000323014200022

  • Formation of heavy d-electron quasiparticles in Sr3Ru2O7 NEW JOURNAL OF PHYSICS Allan, M. P., Tamai, A., Rozbicki, E., Fischer, M. H., Voss, J., King, P. D., Meevasana, W., Thirupathaiah, S., Rienks, E., Fink, J., Tennant, D. A., Perry, R. S., Mercure, J. F., Wang, M. A., Lee, J., Fennie, C. J., Kim, E., Lawler, M. J., Shen, K. M., Mackenzie, A. P., Shen, Z., Baumberger, F. 2013; 15
  • Interaction of itinerant electrons and spin fluctuations in electron-doped cuprates PHYSICAL REVIEW B Park, S. R., Morinari, T., Song, D. J., Leem, C. S., Kim, C., Choi, S. K., Choi, K., Kim, J. H., Schmitt, F., Mo, S. K., Lu, D. H., Shen, Z., Eisaki, H., Tohyama, T., Han, J. H., Kim, C. 2013; 87 (17)
  • Microbead-separated thermionic energy converter with enhanced emission current PHYSICAL CHEMISTRY CHEMICAL PHYSICS Littau, K. A., Sahasrabuddhe, K., Barfield, D., Yuan, H., Shen, Z., Howe, R. T., Melosh, N. A. 2013; 15 (34): 14442-14446

    Abstract

    The efficiency of thermionic energy converters is a strong function of the inter-electrode separation due to space-charge limitations. Here we demonstrate vacuum thermionic energy converters constructed using barium dispenser cathodes and thin film tungsten anodes, separated by size specific alumina microbeads for simple device fabrication and inter-electrode gap control. The current and device efficiency at the maximum power point are strongly dependent on the inter-electrode gap, with a maximum device efficiency of 0.61% observed for a gap on the order of 5 μm. Paths to further reductions in space charge and improved anode work function are outlined with potential for over an order of magnitude improvement in output power and efficiency.

    View details for DOI 10.1039/c3cp52895b

    View details for Web of Science ID 000322725000036

  • PIEZORESISTIVE CANTILEVER PROBES FOR SIMULTANEOUS NANOSCALE TOPOGRAPHY AND CONDUCTIVITY IMAGING 26TH IEEE INTERNATIONAL CONFERENCE ON MICRO ELECTRO MECHANICAL SYSTEMS (MEMS 2013) Yang, Y., Ma, Y., Haemmerli, A., Lai, K., Kundhikanjana, W., Harjee, N., Pruitt, B., Li, X., Kelly, M., Shen, Z. 2013: 323-326
  • Photocathode device using diamondoid and cesium bromide films APPLIED PHYSICS LETTERS Clay, W. A., Maldonado, J. R., Pianetta, P., Dahl, J. E., Carlson, R. M., Schreiner, P. R., Fokin, A. A., Tkachenko, B. A., Melosh, N. A., Shen, Z. 2012; 101 (24)

    View details for DOI 10.1063/1.4769043

    View details for Web of Science ID 000312490000024

  • Phase competition in trisected superconducting dome PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA Vishik, I. M., Hashimoto, M., He, R., LeeB, W., Schmitt, F., Lu, D., Moore, R. G., Zhang, C., Meevasana, W., Sasagawa, T., Uchida, S., Fujita, K., Ishida, S., Ishikado, M., Yoshida, Y., Eisaki, H., Hussain, Z., Devereaux, T. P., Shen, Z. 2012; 109 (45): 18332-18337

    Abstract

    A detailed phenomenology of low energy excitations is a crucial starting point for microscopic understanding of complex materials, such as the cuprate high-temperature superconductors. Because of its unique momentum-space discrimination, angle-resolved photoemission spectroscopy (ARPES) is ideally suited for this task in the cuprates, where emergent phases, particularly superconductivity and the pseudogap, have anisotropic gap structure in momentum space. We present a comprehensive doping- and temperature-dependence ARPES study of spectral gaps in Bi(2)Sr(2)CaCu(2)O(8+?), covering much of the superconducting portion of the phase diagram. In the ground state, abrupt changes in near-nodal gap phenomenology give spectroscopic evidence for two potential quantum critical points, p = 0.19 for the pseudogap phase and p = 0.076 for another competing phase. Temperature dependence reveals that the pseudogap is not static below T(c) and exists p > 0.19 at higher temperatures. Our data imply a revised phase diagram that reconciles conflicting reports about the endpoint of the pseudogap in the literature, incorporates phase competition between the superconducting gap and pseudogap, and highlights distinct physics at the edge of the superconducting dome.

    View details for DOI 10.1073/pnas.1209471109

    View details for Web of Science ID 000311156700031

    View details for PubMedID 23093670

  • A model for emission yield from planar photocathodes based on photon-enhanced thermionic emission or negative-electron-affinity photoemission JOURNAL OF APPLIED PHYSICS Sahasrabuddhe, K., Schwede, J. W., Bargatin, I., Jean, J., Howe, R. T., Shen, Z., Melosh, N. A. 2012; 112 (9)

    View details for DOI 10.1063/1.4764106

    View details for Web of Science ID 000311968400139

  • Batch-fabricated cantilever probes with electrical shielding for nanoscale dielectric and conductivity imaging JOURNAL OF MICROMECHANICS AND MICROENGINEERING Yang, Y., Lai, K., Tang, Q., Kundhikanjana, W., Kelly, M. A., Zhang, K., Shen, Z., Li, X. 2012; 22 (11)
  • Diamondoid coating enables disruptive approach for chemical and magnetic imaging with 10 nm spatial resolution APPLIED PHYSICS LETTERS Ishiwata, H., Acremann, Y., Scholl, A., Rotenberg, E., Hellwig, O., Dobisz, E., Doran, A., Tkachenko, B. A., Fokin, A. A., Schreiner, P. R., Dahl, J. E., Carlson, R. M., Melosh, N., Shen, Z., Ohldag, H. 2012; 101 (16)

    View details for DOI 10.1063/1.4756893

    View details for Web of Science ID 000310669300052

  • Topological insulator nanostructures for near-infrared transparent flexible electrodes NATURE CHEMISTRY Peng, H., Dang, W., Cao, J., Chen, Y., Wu, D., Zheng, W., Li, H., Shen, Z., Liu, Z. 2012; 4 (4): 281-286

    Abstract

    Topological insulators are an intriguing class of materials with an insulating bulk state and gapless Dirac-type edge/surface states. Recent theoretical work predicts that few-layer topological insulators are promising candidates for broadband and high-performance optoelectronic devices due to their spin-momentum-locked massless Dirac edge/surface states, which are topologically protected against all time-reversal-invariant perturbations. Here, we present the first experimental demonstration of near-infrared transparent flexible electrodes based on few-layer topological-insulator Bi(2)Se(3) nanostructures epitaxially grown on mica substrates by means of van der Waals epitaxy. The large, continuous, Bi(2)Se(3)-nanosheet transparent electrodes have single Dirac cone surface states, and exhibit sheet resistances as low as ~330 ? per square, with a transparency of more than 70% over a wide range of wavelengths. Furthermore, Bi(2)Se(3)-nanosheet transparent electrodes show high chemical and thermal stabilities as well as excellent mechanical durability, which may lead to novel optoelectronic devices with unique properties.

    View details for DOI 10.1038/nchem.1277

    View details for Web of Science ID 000301983400013

    View details for PubMedID 22437712

  • Energy scale directly related to superconductivity in high-T-c cuprates: Universality from the temperature-dependent angle-resolved photoemission of Bi2Sr2Ca2Cu3O10+delta PHYSICAL REVIEW B Ideta, S., Yoshida, T., Fujimori, A., Anzai, H., Fujita, T., Ino, A., Arita, M., Namatame, H., Taniguchi, M., Shen, Z., Takashima, K., Kojima, K., Uchida, S. 2012; 85 (10)
  • Angle-Resolved Photoemission Studies of Quantum Materials ANNUAL REVIEW OF CONDENSED MATTER PHYSICS, VOL 3 Lu, D., Vishik, I. M., Yi, M., Chen, Y., Moore, R. G., Shen, Z. 2012; 3: 129-167
  • Pseudogap, Superconducting Gap, and Fermi Arc in High-T-c Cuprates Revealed by Angle-Resolved Photoemission Spectroscopy JOURNAL OF THE PHYSICAL SOCIETY OF JAPAN Yoshida, T., Hashimoto, M., Vishik, I. M., Shen, Z., Fujimori, A. 2012; 81 (1)
  • Photoluminescence of diamondoid crystals JOURNAL OF APPLIED PHYSICS Clay, W. A., Sasagawa, T., Iwasa, A., Liu, Z., Dahl, J. E., Carlson, R. M., Kelly, M., Melosh, N., Shen, Z. 2011; 110 (9)

    View details for DOI 10.1063/1.3657522

    View details for Web of Science ID 000297062100028

  • 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

  • Imaging of Coulomb-Driven Quantum Hall Edge States PHYSICAL REVIEW LETTERS Lai, K., Kundhikanjana, W., Kelly, M. A., Shen, Z., Shabani, J., Shayegan, M. 2011; 107 (17)

    Abstract

    The edges of a two-dimensional electron gas (2DEG) in the quantum Hall effect (QHE) regime are divided into alternating metallic and insulating strips, with their widths determined by the energy gaps of the QHE states and the electrostatic Coulomb interaction. Local probing of these submicrometer features, however, is challenging due to the buried 2DEG structures. Using a newly developed microwave impedance microscope, we demonstrate the real-space conductivity mapping of the edge and bulk states. The sizes, positions, and field dependence of the edge strips around the sample perimeter agree quantitatively with the self-consistent electrostatic picture. The evolution of microwave images as a function of magnetic fields provides rich microscopic information around the ?=2 QHE state.

    View details for DOI 10.1103/PhysRevLett.107.176809

    View details for Web of Science ID 000296984100011

    View details for PubMedID 22107561

  • Polaronic metal in lightly doped high-T-c cuprates EPL Mishchenko, A. S., Nagaosa, N., Shen, K. M., Shen, Z., Zhou, X. J., Devereaux, T. P. 2011; 95 (5)
  • 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
  • Cryogenic microwave imaging of metal-insulator transition in doped silicon REVIEW OF SCIENTIFIC INSTRUMENTS Kundhikanjana, W., Lai, K., Kelly, M. A., Shen, Z. 2011; 82 (3)

    Abstract

    We report the instrumentation and experimental results of a cryogenic scanning microwave impedance microscope. The microwave probe and the scanning stage are located inside the variable temperature insert of a helium cryostat. Microwave signals in the distance modulation mode are used for monitoring the tip-sample distance and adjusting the phase of the two output channels. The ability to spatially resolve the metal-insulator transition in a doped silicon sample is demonstrated. The data agree with a semiquantitative finite element simulation. Effects of the thermal energy and electric fields on local charge carriers can be seen in the images taken at different temperatures and dc biases.

    View details for DOI 10.1063/1.3554438

    View details for Web of Science ID 000289149600040

    View details for PubMedID 21456749

  • Photon-enhanced thermionic emission for solar concentrator systems NATURE MATERIALS Schwede, J. W., Bargatin, I., Riley, D. C., Hardin, B. E., Rosenthal, S. J., Sun, Y., Schmitt, F., Pianetta, P., Howe, R. T., Shen, Z., Melosh, N. A. 2010; 9 (9): 762-767

    Abstract

    Solar-energy conversion usually takes one of two forms: the 'quantum' approach, which uses the large per-photon energy of solar radiation to excite electrons, as in photovoltaic cells, or the 'thermal' approach, which uses concentrated sunlight as a thermal-energy source to indirectly produce electricity using a heat engine. Here we present a new concept for solar electricity generation, photon-enhanced thermionic emission, which combines quantum and thermal mechanisms into a single physical process. The device is based on thermionic emission of photoexcited electrons from a semiconductor cathode at high temperature. Temperature-dependent photoemission-yield measurements from GaN show strong evidence for photon-enhanced thermionic emission, and calculated efficiencies for idealized devices can exceed the theoretical limits of single-junction photovoltaic cells. The proposed solar converter would operate at temperatures exceeding 200 degrees C, enabling its waste heat to be used to power a secondary thermal engine, boosting theoretical combined conversion efficiencies above 50%.

    View details for DOI 10.1038/NMAT2814

    View details for Web of Science ID 000281178400029

    View details for PubMedID 20676086

  • Ultrathin Topological Insulator Bi2Se3 Nanoribbons Exfoliated by Atomic Force Microscopy NANO LETTERS Hong, S. S., Kundhikanjana, W., Cha, J. J., Lai, K., Kong, D., Meister, S., Kelly, M. A., Shen, Z., Cui, Y. 2010; 10 (8): 3118-3122

    Abstract

    Ultrathin topological insulator nanostructures, in which coupling between top and bottom surface states takes place, are of great intellectual and practical importance. Due to the weak van der Waals interaction between adjacent quintuple layers (QLs), the layered bismuth selenide (Bi(2)Se(3)), a single Dirac-cone topological insulator with a large bulk gap, can be exfoliated down to a few QLs. In this paper, we report the first controlled mechanical exfoliation of Bi(2)Se(3) nanoribbons (>50 QLs) by an atomic force microscope (AFM) tip down to a single QL. Microwave impedance microscopy is employed to map out the local conductivity of such ultrathin nanoribbons, showing drastic difference in sheet resistance between 1-2 QLs and 4-5 QLs. Transport measurement carried out on an exfoliated (50 QLs) ribbons. These AFM-exfoliated thin nanoribbons afford interesting candidates for studying the transition from quantum spin Hall surface to edge states.

    View details for DOI 10.1021/nl1018E4h

    View details for Web of Science ID 000280728900065

    View details for PubMedID 20698625

  • Mesoscopic Percolating Resistance Network in a Strained Manganite Thin Film SCIENCE Lai, K., Nakamura, M., Kundhikanjana, W., Kawasaki, M., Tokura, Y., Kelly, M. A., Shen, Z. 2010; 329 (5988): 190-193

    Abstract

    Many unusual behaviors in complex oxides are deeply associated with the spontaneous emergence of microscopic phase separation. Depending on the underlying mechanism, the competing phases can form ordered or random patterns at vastly different length scales. By using a microwave impedance microscope, we observed an orientation-ordered percolating network in strained Nd(1/2)Sr(1/2)MnO3 thin films with a large period of 100 nanometers. The filamentary metallic domains align preferentially along certain crystal axes of the substrate, suggesting the anisotropic elastic strain as the key interaction in this system. The local impedance maps provide microscopic electrical information of the hysteretic behavior in strained thin film manganites, suggesting close connection between the glassy order and the colossal magnetoresistance effects at low temperatures.

    View details for DOI 10.1126/science.1189925

    View details for Web of Science ID 000279635200041

    View details for PubMedID 20616272

  • Particle-hole symmetry breaking in the pseudogap state of Bi2201 NATURE PHYSICS Hashimoto, M., He, R., Tanaka, K., Testaud, J., Meevasana, W., Moore, R. G., Lu, D., Yao, H., Yoshida, Y., Eisaki, H., Devereaux, T. P., Hussain, Z., Shen, Z. 2010; 6 (6): 414-418

    View details for DOI 10.1038/NPHYS1632

    View details for Web of Science ID 000279014400011

  • Aharonov-Bohm interference in topological insulator nanoribbons NATURE MATERIALS Peng, H., Lai, K., Kong, D., Meister, S., Chen, Y., Qi, X., Zhang, S., Shen, Z., Cui, Y. 2010; 9 (3): 225-229

    Abstract

    Topological insulators represent unusual phases of quantum matter with an insulating bulk gap and gapless edges or surface states. The two-dimensional topological insulator phase was predicted in HgTe quantum wells and confirmed by transport measurements. Recently, Bi(2)Se(3) and related materials have been proposed as three-dimensional topological insulators with a single Dirac cone on the surface, protected by time-reversal symmetry. The topological surface states have been observed by angle-resolved photoemission spectroscopy experiments. However, few transport measurements in this context have been reported, presumably owing to the predominance of bulk carriers from crystal defects or thermal excitations. Here we show unambiguous transport evidence of topological surface states through periodic quantum interference effects in layered single-crystalline Bi(2)Se(3) nanoribbons, which have larger surface-to-volume ratios than bulk materials and can therefore manifest surface effects. Pronounced Aharonov-Bohm oscillations in the magnetoresistance clearly demonstrate the coherent propagation of two-dimensional electrons around the perimeter of the nanoribbon surface, as expected from the topological nature of the surface states. The dominance of the primary h/e oscillation, where h is Planck's constant and e is the electron charge, and its temperature dependence demonstrate the robustness of these states. Our results suggest that topological insulator nanoribbons afford promising materials for future spintronic devices at room temperature.

    View details for DOI 10.1038/NMAT2609

    View details for Web of Science ID 000274700900017

    View details for PubMedID 20010826

  • Evolution of electronic structure from insulator to superconductor in Bi2Sr2-xLax(Ca,Y)Cu2O8+delta PHYSICAL REVIEW B Tanaka, K., Yoshida, T., Shen, K. M., Lu, D. H., Lee, W. S., Yagi, H., Fujimori, A., Shen, Z., Risdiana, R., Fujii, T., Terasaki, I. 2010; 81 (12)
  • Environmentally Friendly Refining of Diamond-Molecules via the Growth of Large Single Crystals CRYSTAL GROWTH & DESIGN Iwasa, A., Clay, W. A., Dahl, J. E., Carlson, R. M., Shen, Z., Sasagawa, T. 2010; 10 (2): 870-873

    View details for DOI 10.1021/cg901218t

    View details for Web of Science ID 000274837000056

  • Topological Insulator Nanowires and Nanoribbons NANO LETTERS Kong, D., Randel, J. C., Peng, H., Cha, J. J., Meister, S., Lai, K., Chen, Y., Shen, Z., Manoharan, H. C., Cui, Y. 2010; 10 (1): 329-333

    Abstract

    Recent theoretical calculations and photoemission spectroscopy measurements on the bulk Bi(2)Se(3) material show that it is a three-dimensional topological insulator possessing conductive surface states with nondegenerate spins, attractive for dissipationless electronics and spintronics applications. Nanoscale topological insulator materials have a large surface-to-volume ratio that can manifest the conductive surface states and are promising candidates for devices. Here we report the synthesis and characterization of high quality single crystalline Bi(2)Se(3) nanomaterials with a variety of morphologies. The synthesis of Bi(2)Se(3) nanowires and nanoribbons employs Au-catalyzed vapor-liquid-solid (VLS) mechanism. Nanowires, which exhibit rough surfaces, are formed by stacking nanoplatelets along the axial direction of the wires. Nanoribbons are grown along [1120] direction with a rectangular cross-section and have diverse morphologies, including quasi-one-dimensional, sheetlike, zigzag and sawtooth shapes. Scanning tunneling microscopy (STM) studies on nanoribbons show atomically smooth surfaces with approximately 1 nm step edges, indicating single Se-Bi-Se-Bi-Se quintuple layers. STM measurements reveal a honeycomb atomic lattice, suggesting that the STM tip couples not only to the top Se atomic layer, but also to the Bi atomic layer underneath, which opens up the possibility to investigate the contribution of different atomic orbitals to the topological surface states. Transport measurements of a single nanoribbon device (four terminal resistance and Hall resistance) show great promise for nanoribbons as candidates to study topological surface states.

    View details for DOI 10.1021/nl903663a

    View details for Web of Science ID 000273428700055

    View details for PubMedID 20030392

  • Hierarchy of Electronic Properties of Chemically Derived and Pristine Graphene Probed by Microwave Imaging NANO LETTERS Kundhikanjana, W., Lai, K., Wang, H., Dai, H., Kelly, M. A., Shen, Z. 2009; 9 (11): 3762-3765

    Abstract

    Local electrical imaging using microwave impedance microscope is performed on graphene in different modalities, yielding a rich hierarchy of the local conductivity. The low-conductivity graphite oxide and its derivatives show significant electronic inhomogeneity. For the conductive chemical graphene, the residual defects lead to a systematic reduction of the microwave signals. In contrast, the signals on pristine graphene agree well with a lumped-element circuit model. The local impedance information can also be used to verify the electrical contact between overlapped graphene pieces.

    View details for DOI 10.1021/nl901949z

    View details for Web of Science ID 000271566400017

    View details for PubMedID 19678669

  • Nanoscale Electronic Inhomogeneity in In2Se3 Nanoribbons Revealed by Microwave Impedance Microscopy NANO LETTERS Lai, K., Peng, H., Kundhikanjana, W., Schoen, D. T., Xie, C., Meister, S., Cui, Y., Kelly, M. A., Shen, Z. 2009; 9 (3): 1265-1269

    View details for DOI 10.1021/nl900222j

    View details for Web of Science ID 000264142100060

  • Energy gaps in the failed high-T-c superconductor La1:875Ba0:125CuO4 NATURE PHYSICS He, R., Tanaka, K., Mo, S., Sasagawa, T., Fujita, M., Adachi, T., Mannella, N., Yamada, K., Koike, Y., Hussain, Z., Shen, Z. 2009; 5 (2): 119-123

    View details for DOI 10.1038/NPHYS1159

    View details for Web of Science ID 000263458500015

  • Origin of the Monochromatic Photoemission Peak in Diamondoid Monolayers NANO LETTERS Clay, W. A., Liu, Z., Yang, W., Fabbri, J. D., Dahl, J. E., Carlson, R. M., Sun, Y., Schreiner, P. R., Fokin, A. A., Tkachenko, B. A., Fokina, N. A., Pianetta, P. A., Melosh, N., Shen, Z. 2009; 9 (1): 57-61

    Abstract

    Recent photoemission experiments have discovered a highly monochromatized secondary electron peak emitted from diamondoid self-assembled monolayers on metal substrates. New experimental data and simulation results are presented to show that a combination of negative electron affinity and strong electron-phonon scattering is responsible for this behavior. The simulation results are generated using a simple Monte Carlo transport algorithm. The simulated spectra recreate the main spectral features of the measured ones.

    View details for DOI 10.1021/nl802310k

    View details for Web of Science ID 000262519100010

    View details for PubMedID 18975993

  • Intrinsic electron and hole bands in electron-doped cuprate superconductors PHYSICAL REVIEW B Xiang, T., Luo, H. G., Lu, D. H., Shen, K. M., Shen, Z. X. 2009; 79 (1)
  • A route to tunable direct band-gap diamond devices: Electronic structures of nanodiamond crystals JOURNAL OF APPLIED PHYSICS Sasagawa, T., Shen, Z. 2008; 104 (7)

    View details for DOI 10.1063/1.2986637

    View details for Web of Science ID 000260125500066

  • 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

  • Modeling and characterization of a cantilever-based near-field scanning microwave impedance microscope REVIEW OF SCIENTIFIC INSTRUMENTS Lai, K., Kundhikanjana, W., Kelly, M., Shen, Z. X. 2008; 79 (6)

    Abstract

    This paper presents a detailed modeling and characterization of a microfabricated cantilever-based scanning microwave probe with separated excitation and sensing electrodes. Using finite-element analysis, we model the tip-sample interaction as small impedance changes between the tip electrode and the ground at our working frequencies near 1 GHz. The equivalent lumped elements of the cantilever can be determined by transmission line simulation of the matching network, which routes the cantilever signals to 50 Omega feed lines. In the microwave electronics, the background common-mode signal is canceled before the amplifier stage so that high sensitivity (below 1 aF capacitance changes) is obtained. Experimental characterization of the microwave microscope was performed on ion-implanted Si wafers and patterned semiconductor samples. Pure electrical or topographical signals can be obtained from different reflection modes of the probe.

    View details for DOI 10.1063/1.2949109

    View details for Web of Science ID 000257283700020

    View details for PubMedID 18601409

  • Uncovering a pressure-tuned electronic transition in Bi1.98Sr2.06Y0.68Cu2O8+delta using Raman scattering and x-ray diffraction PHYSICAL REVIEW LETTERS Cuk, T., Struzhkin, V. V., Devereaux, T. P., Goncharov, A. F., Kendziora, C. A., Eisaki, H., Mao, H., Shen, Z. 2008; 100 (21)

    Abstract

    We report pressure-tuned Raman and x-ray diffraction data of Bi(1.98.)Sr(2.06)Y(0.68)Cu(2)O(8+delta) revealing a critical pressure at 21 GPa with anomalies in electronic Raman background, electron-phonon coupling lambda, spectral weight transfer, density dependent behavior of phonons and magnons, and a compressibility change in the c axis. For the first time in a cuprate, mobile charge carriers, lattice, and magnetism all show anomalies at a distinct critical pressure in the same experimental setting. Furthermore, the spectral changes suggest that the critical pressure at 21 GPa is related to the critical point at optimal doping.

    View details for DOI 10.1103/PhysRevLett.100.217003

    View details for Web of Science ID 000256585500042

    View details for PubMedID 18518627

  • Evolution of the fermi surface and quasiparticle renormalization through a van hove singularity in Sr2-yLayRuO4 PHYSICAL REVIEW LETTERS Shen, K. M., Kikugawa, N., Bergemann, C., Balicas, L., Baumberger, F., Meevasana, W., Ingle, N. J., Maeno, Y., Shen, Z., Mackenzie, A. P. 2007; 99 (18)

    Abstract

    We employ a combination of chemical substitution and angle resolved photoemission spectroscopy to prove that the Fermi level in the gamma band of Sr(2-y)La(y)RuO(4) can be made to traverse a van Hove singularity. Remarkably, the large mass renormalization has little dependence on either k or doping. By combining the results from photoemission with thermodynamic measurements on the same batches of crystals, we deduce a parametrization of the full many-body quasiparticle dispersion in Sr(2)RuO(4) which extends from the Fermi level to approximately 20 meV above it.

    View details for DOI 10.1103/PhysRevLett.99.187001

    View details for Web of Science ID 000250644000045

    View details for PubMedID 17995427

  • Abrupt onset of a second energy gap at the superconducting transition of underdoped Bi2212 NATURE Lee, W. S., Vishik, I. M., Tanaka, K., Lu, D. H., Sasagawa, T., Nagaosa, N., Devereaux, T. P., Hussain, Z., Shen, Z. 2007; 450 (7166): 81-84

    Abstract

    The superconducting gap--an energy scale tied to the superconducting phenomena--opens on the Fermi surface at the superconducting transition temperature (T(c)) in conventional BCS superconductors. In underdoped high-T(c) superconducting copper oxides, a pseudogap (whose relation to the superconducting gap remains a mystery) develops well above T(c) (refs 1, 2). Whether the pseudogap is a distinct phenomenon or the incoherent continuation of the superconducting gap above T(c) is one of the central questions in high-T(c) research. Although some experimental evidence suggests that the two gaps are distinct, this issue is still under intense debate. A crucial piece of evidence to firmly establish this two-gap picture is still missing: a direct and unambiguous observation of a single-particle gap tied to the superconducting transition as function of temperature. Here we report the discovery of such an energy gap in underdoped Bi2Sr2CaCu2O8+delta in the momentum space region overlooked in previous measurements. Near the diagonal of Cu-O bond direction (nodal direction), we found a gap that opens at T(c) and has a canonical (BCS-like) temperature dependence accompanied by the appearance of the so-called Bogoliubov quasi-particles, a classical signature of superconductivity. This is in sharp contrast to the pseudogap near the Cu-O bond direction (antinodal region) measured in earlier experiments.

    View details for DOI 10.1038/nature06219

    View details for Web of Science ID 000250585800040

    View details for PubMedID 17972881

  • Monochromatic electron photoemission from diamondoid monolayers SCIENCE Yang, W. L., Fabbri, J. D., Willey, T. M., Lee, J. R., Dahl, J. E., Carlson, R. M., Schreiner, P. R., Fokin, A. A., Tkachenko, B. A., Fokina, N. A., Meevasana, W., Mannella, N., Tanaka, K., Zhou, X. J., van Buuren, T., Kelly, M. A., Hussain, Z., Melosh, N. A., Shen, Z. 2007; 316 (5830): 1460-1462

    Abstract

    We found monochromatic electron photoemission from large-area self-assembled monolayers of a functionalized diamondoid, [121]tetramantane-6-thiol. Photoelectron spectra of the diamondoid monolayers exhibited a peak at the low-kinetic energy threshold; up to 68% of all emitted electrons were emitted within this single energy peak. The intensity of the emission peak is indicative of diamondoids being negative electron affinity materials. With an energy distribution width of less than 0.5 electron volts, this source of monochromatic electrons may find application in technologies such as electron microscopy, electron beam lithography, and field-emission flat-panel displays.

    View details for DOI 10.1126/science.1141811

    View details for Web of Science ID 000247066400037

    View details for PubMedID 17556579

  • Atomic-force-microscope-compatible near-field scanning microwave microscope with separated excitation and sensing probes REVIEW OF SCIENTIFIC INSTRUMENTS Lai, K., Ji, M. B., Leindecker, N., Kelly, M. A., Shen, Z. X. 2007; 78 (6)

    Abstract

    We present the design and experimental results of a near-field scanning microwave microscope working at a frequency of 1 GHz. Our microscope is unique in that the sensing probe is separated from the excitation electrode to significantly suppress the common-mode signal. Coplanar waveguides were patterned onto a silicon nitride cantilever interchangeable with atomic force microscope tips, which are robust for high speed scanning. In the contact mode that we are currently using, the numerical analysis shows that contrast comes from both the variation in local dielectric properties and the sample topography. Our microscope demonstrates the ability to achieve high resolution microwave images on buried structures, as well as nanoparticles, nanowires, and biological samples.

    View details for DOI 10.1063/1.2746768

    View details for Web of Science ID 000247626200014

    View details for PubMedID 17614611

  • Ca3Ru2O7: Electronic instability and extremely strong quasiparticle renormalisation JOURNAL OF MAGNETISM AND MAGNETIC MATERIALS Kikugawa, N., Rost, A., Baumberger, F., Ingle, N. J., Hossain, M. A., Meevasana, W., Shen, K. M., Lu, D. H., Damascelli, A., Mackenzie, A. P., Hussain, Z., Shen, Z. X. 2007; 310 (2): 1027-1029
  • Angle-resolved photoemission studies of lattice polaron formation in the cuprate Ca2CuO2Cl2 PHYSICAL REVIEW B Shen, K. M., Ronning, F., Meevasana, W., Lu, D. H., Ingle, N. J., Baumberger, F., Lee, W. S., MILLER, L. L., Kohsaka, Y., Azuma, M., Takano, M., Takagi, H., Shen, Z. 2007; 75 (7)
  • Distinct Fermi-momentum-dependent energy gaps in deeply underdoped Bi2212 SCIENCE Tanaka, K., Lee, W. S., Lu, D. H., Fujimori, A., Fujii, T., Risdiana, Terasaki, I., Scalapino, D. J., Devereaux, T. P., Hussain, Z., Shen, Z. 2006; 314 (5807): 1910-1913

    Abstract

    We used angle-resolved photoemission spectroscopy applied to deeply underdoped cuprate superconductors Bi2Sr2Ca(1-x)YxCu2O8 (Bi2212) to reveal the presence of two distinct energy gaps exhibiting different doping dependence. One gap, associated with the antinodal region where no coherent peak is observed, increased with underdoping, a behavior known for more than a decade and considered as the general gap behavior in the underdoped regime. The other gap, associated with the near-nodal regime where a coherent peak in the spectrum can be observed, did not increase with less doping, a behavior not previously observed in the single particle spectra. We propose a two-gap scenario in momentum space that is consistent with other experiments and may contain important information on the mechanism of high-transition temperature superconductivity.

    View details for DOI 10.1126/science.1133411

    View details for Web of Science ID 000242996800043

    View details for PubMedID 17114172

  • Anomalous Fermi-surface dependent pairing in a self-doped high-T-c superconductor PHYSICAL REVIEW LETTERS Chen, Y., Iyo, A., Yang, W., Zhou, X., Lu, D., Eisaki, H., Devereaux, T. P., Hussain, Z., Shen, Z. 2006; 97 (23)

    Abstract

    We report the discovery of a self-doped multilayer high Tc superconductor Ba2Ca3Cu4O8F2 (F0234) which contains distinctly different superconducting gap magnitudes along its two Fermi-surface sheets. While formal valence counting would imply this material to be an undoped insulator, it is a self-doped superconductor with a Tc of 60 K, possessing simultaneously both electron- and hole-doped Fermi-surface sheets. Intriguingly, the Fermi-surface sheet characterized by the much larger gap is the electron-doped one, which has a shape disfavoring two electronic features considered to be important for the pairing mechanism: the van Hove singularity and the antiferromagnetic (pi/a, pi/a) scattering.

    View details for DOI 10.1103/PhysRevLett.97.236401

    View details for Web of Science ID 000242708900037

    View details for PubMedID 17280217

  • Calculation of overdamped c-axis charge dynamics and the coupling to polar phonons in cuprate superconductors PHYSICAL REVIEW B Meevasana, W., Devereaux, T. P., Nagaosa, N., Shen, Z., Zaanen, J. 2006; 74 (17)
  • Fermi surface and quasiparticle excitations of Sr2RhO4 PHYSICAL REVIEW LETTERS Baumberger, F., Ingle, N. J., Meevasana, W., Shen, K. M., Lu, D. H., Perry, R. S., Mackenzie, A. P., Hussain, Z., Singh, D. J., Shen, Z. 2006; 96 (24)

    Abstract

    The electronic structure of the layered 4d transition metal oxide Sr2RhO4 is investigated by angle resolved photoemission. We find well-defined quasiparticle excitations with a highly anisotropic dispersion, suggesting a quasi-two-dimensional Fermi-liquid-like ground state. Markedly different from the isostructural Sr2RuO4, only two bands with dominant Rh 4dxz,zy character contribute to the Fermi surface. A quantitative analysis of the photoemission quasiparticle band structure is in excellent agreement with bulk data. In contrast, it is found that state-of-the-art density functional calculations in the local density approximation differ significantly from the experimental findings.

    View details for DOI 10.1103/PhysRevLett.96.246402

    View details for Web of Science ID 000238487900041

    View details for PubMedID 16907260

  • Doping dependence of the coupling of electrons to bosonic modes in the single-layer high-temperature Bi2Sr2CuO6 superconductor PHYSICAL REVIEW LETTERS Meevasana, W., Ingle, N. J., Lu, D. H., Shi, J. R., Baumberger, F., Shen, K. M., Lee, W. S., Cuk, T., Eisaki, H., Devereaux, T. P., Nagaosa, N., Zaanen, J., Shen, Z. X. 2006; 96 (15)

    Abstract

    A recent highlight in the study of high-T(c) superconductors is the observation of band renormalization or self-energy effects on the quasiparticles. This is seen in the form of kinks in the quasiparticle dispersions as measured by photoemission and interpreted as signatures of collective bosonic modes coupling to the electrons. Here we compare for the first time the self-energies in an optimally doped and strongly overdoped, nonsuperconducting single-layer Bi-cuprate (Bi2Sr2CuO6). In addition to the appearance of a strong overall weakening, we also find that the weight of the self-energy in the overdoped system shifts to higher energies. We present evidence that this is related to a change in the coupling to c-axis phonons due to the rapid change of the c-axis screening in this doping range.

    View details for DOI 10.1103/PhysRevLett.96.157003

    View details for Web of Science ID 000236969700057

    View details for PubMedID 16712188

  • Nested Fermi surface and electronic instability in Ca3Ru2O7 PHYSICAL REVIEW LETTERS Baumberger, F., Ingle, N. J., Kikugawa, N., Hossain, M. A., Meevasana, W., Perry, R. S., Shen, K. M., Lu, D. H., Damascelli, A., Rost, A., Mackenzie, A. P., Hussain, Z., Shen, Z. X. 2006; 96 (10)

    Abstract

    High-resolution angular resolved photoemission data reveal well-defined quasiparticle bands of unusually low weight, emerging in line with the metallic phase of Ca(3)Ru(2)O(7) below approximately 30 K . At the bulk structural phase transition temperature of 48 K, we find clear evidence for an electronic instability, gapping large parts of the underlying Fermi surface that appears to be nested. Metallic pockets are found to survive in the small, non-nested sections, constituting a low-temperature Fermi surface with 2 orders of magnitude smaller volume than in all other metallic ruthenates. The Fermi velocities and volumes of these pockets are in agreement with the results of complementary quantum oscillation measurements on the same crystal batches.

    View details for DOI 10.1103/PhysRevLett.96.107601

    View details for Web of Science ID 000236062800079

    View details for PubMedID 16605788

  • Nodal quasiparticle in pseudogapped colossal magnetoresistive manganites NATURE Mannella, N., Yang, W. L., Zhou, X. J., Zheng, H., Mitchell, J. F., Zaanen, J., Devereaux, T. P., Nagaosa, N., Hussain, Z., Shen, Z. X. 2005; 438 (7067): 474-478

    Abstract

    A characteristic feature of the copper oxide high-temperature superconductors is the dichotomy between the electronic excitations along the nodal (diagonal) and antinodal (parallel to the Cu-O bonds) directions in momentum space, generally assumed to be linked to the 'd-wave' symmetry of the superconducting state. Angle-resolved photoemission measurements in the superconducting state have revealed a quasiparticle spectrum with a d-wave gap structure that exhibits a maximum along the antinodal direction and vanishes along the nodal direction. Subsequent measurements have shown that, at low doping levels, this gap structure persists even in the high-temperature metallic state, although the nodal points of the superconducting state spread out in finite 'Fermi arcs'. This is the so-called pseudogap phase, and it has been assumed that it is closely linked to the superconducting state, either by assigning it to fluctuating superconductivity or by invoking orders which are natural competitors of d-wave superconductors. Here we report experimental evidence that a very similar pseudogap state with a nodal-antinodal dichotomous character exists in a system that is markedly different from a superconductor: the ferromagnetic metallic groundstate of the colossal magnetoresistive bilayer manganite La1.2Sr1.8Mn2O7. Our findings therefore cast doubt on the assumption that the pseudogap state in the copper oxides and the nodal-antinodal dichotomy are hallmarks of the superconductivity state.

    View details for DOI 10.1038/nature04273

    View details for Web of Science ID 000233458200044

    View details for PubMedID 16306987

  • Quantitative analysis of Sr2RuO4 angle-resolved photoemission spectra: Many-body interactions in a model Fermi liquid PHYSICAL REVIEW B Ingle, N. J., Shen, K. M., Baumberger, F., Meevasana, W., Lu, D. H., Shen, Z. X., Damascelli, A., Nakatsuji, S., Mao, Z. Q., Maeno, Y., Kimura, T., Tokura, Y. 2005; 72 (20)
  • Multiple bosonic mode coupling in the electron self-energy of (La2-xSrx)CuO4 PHYSICAL REVIEW LETTERS Zhou, X. J., Shi, J. R., Yoshida, T., Cuk, T., Yang, W. L., Brouet, V., Nakamura, J., Mannella, N., Komiya, S., Ando, Y., Zhou, F., Ti, W. X., Xiong, J. W., Zhao, Z. X., Sasagawa, T., Kakeshita, T., Eisaki, H., Uchida, S., Fujimori, A., Zhang, Z. Y., Plummer, E. W., Laughlin, R. B., Hussain, Z., Shen, Z. X. 2005; 95 (11)

    Abstract

    High resolution angle-resolved photoemission spectroscopy data along the (0,0)-(pi,pi) nodal direction with significantly improved statistics reveal fine structure in the electron self-energy of the underdoped (La2-xSrx)CuO4 samples in the normal state. Fine structure at energies of (40-46) meV and (58-63) meV, and possible fine structure at energies of (23-29) meV and (75-85) meV, have been identified. These observations indicate that, in (La2-xSrx)CuO4, more than one bosonic modes are involved in the coupling with electrons.

    View details for DOI 10.1103/PhysRevLett.95.117001

    View details for Web of Science ID 000231802000055

    View details for PubMedID 16197033

  • Anomalous high-energy dispersion in angle-resolved photoemission spectra from the insulating cuprate Ca2CuO2Cl2 PHYSICAL REVIEW B Ronning, F., Shen, K. M., Armitage, N. P., Damascelli, A., Lu, D. H., Shen, Z. X., MILLER, L. L., Kim, C. 2005; 71 (9)
  • Nodal quasiparticles and antinodal charge ordering in Ca2-xNaxCuO2Cl2 SCIENCE Shen, K. M., Ronning, F., Lu, D. H., Baumberger, F., Ingle, N. J., Lee, W. S., Meevasana, W., Kohsaka, Y., Azuma, M., Takano, M., Takagi, H., Shen, Z. X. 2005; 307 (5711): 901-904

    Abstract

    Understanding the role of competing states in the cuprates is essential for developing a theory for high-temperature superconductivity. We report angle-resolved photoemission spectroscopy experiments which probe the 4a0 x 4a0 charge-ordered state discovered by scanning tunneling microscopy in the lightly doped cuprate superconductor Ca2-xNaxCuO2Cl2. Our measurements reveal a marked dichotomy between the real- and momentum-space probes, for which charge ordering is emphasized in the tunneling measurements and photoemission is most sensitive to excitations near the node of the d-wave superconducting gap. These results emphasize the importance of momentum anisotropy in determining the complex electronic properties of the cuprates and places strong constraints on theoretical models of the charge-ordered state.

    View details for DOI 10.1126/science.1103627

    View details for Web of Science ID 000226985100046

    View details for PubMedID 15705845

  • Missing quasiparticles and the chemical potential puzzle in the doping evolution of the cuprate superconductors PHYSICAL REVIEW LETTERS Shen, K. M., Ronning, F., Lu, D. H., Lee, W. S., Ingle, N. J., Meevasana, W., Baumberger, F., Damascelli, A., Armitage, N. P., MILLER, L. L., Kohsaka, Y., Azuma, M., Takano, M., Takagi, H., Shen, Z. X. 2004; 93 (26)

    Abstract

    The evolution of Ca2-xNaxCuO2Cl2 from Mott insulator to superconductor was studied using angle-resolved photoemission spectroscopy. By measuring both the excitations near the Fermi energy as well as nonbonding states, we tracked the doping dependence of the electronic structure and the chemical potential with unprecedented precision. Our work reveals failures in the standard weakly interacting quasiparticle scenario, including the broad line shapes of the insulator and the apparently paradoxical shift of the chemical potential within the Mott gap. To resolve this, we develop a model where the quasiparticle is vanishingly small at half filling and grows upon doping, allowing us to unify properties such as the dispersion and Fermi wave vector with the chemical potential.

    View details for DOI 10.1103/PhysRevLett.93.267002

    View details for Web of Science ID 000226054600054

    View details for PubMedID 15698008

  • Coupling of the B-1g phonon to the antinodal electronic states of Bi2Sr2Ca0.92Y0.08Cu2O8+delta PHYSICAL REVIEW LETTERS Cuk, T., Baumberger, F., Lu, D. H., Ingle, N., Zhou, X. J., Eisaki, H., Kaneko, N., Hussain, Z., Devereaux, T. P., Nagaosa, N., Shen, Z. X. 2004; 93 (11)

    Abstract

    Angle-resolved photoemission spectroscopy on optimally doped Bi(2)Sr(2)Ca(0.92)Y(0.08)Cu(2)O(8+delta) uncovers a coupling of the electronic bands to a 40 meV mode in an extended k-space region away from the nodal direction, leading to a new interpretation of the strong renormalization of the electronic structure seen in Bi2212. Phenomenological agreements with neutron and Raman experiments suggest that this mode is the B(1g) oxygen bond-buckling phonon. A theoretical calculation based on this assignment reproduces the electronic renormalization seen in the data.

    View details for DOI 10.1103/PhysRevLett.93.117003

    View details for Web of Science ID 000223794400050

    View details for PubMedID 15447370

  • Dichotomy between nodal and antinodal quasiparticles in underdoped (La2-xSrx)CuO4 superconductors PHYSICAL REVIEW LETTERS Zhou, X. J., Yoshida, T., Lee, D. H., Yang, W. L., Brouet, V., Zhou, F., Ti, W. X., Xiong, J. W., Zhao, Z. X., Sasagawa, T., Kakeshita, T., Eisaki, H., Uchida, S., Fujimori, A., Hussain, Z., Shen, Z. X. 2004; 92 (18)

    Abstract

    High resolution angle-resolved photoemission measurements on an underdoped (La(2-x)Srx)CuO4 system show that, at energies below 70 meV, the quasiparticle peak is well defined around the (pi/2,pi/2) nodal region and disappears rather abruptly when the momentum is changed from the nodal point to the (pi,0) antinodal point along the underlying "Fermi surface." It indicates that there is an extra low energy scattering mechanism acting upon the antinodal quasiparticles. We propose that this mechanism is the scattering of quasiparticles across the nearly parallel segments of the Fermi surface near the antinodes.

    View details for DOI 10.1103/PhysRevLett.92.187001

    View details for Web of Science ID 000221277900054

    View details for PubMedID 15169524

  • Fully gapped single-particle excitations in lightly doped cuprates PHYSICAL REVIEW B Shen, K. M., Yoshida, T., Lu, D. H., Ronning, F., Armitage, N. P., Lee, W. S., Zhou, X. J., Damascelli, A., Feng, D. L., Ingle, N. J., Eisaki, H., Kohsaka, Y., Takagi, H., Kakeshita, T., Uchida, S., Mang, P. K., Greven, M., Onose, Y., Taguchi, Y., Tokura, Y., Komiya, S., Ando, Y., Azuma, M., Takano, M., Fujimori, A., Shen, Z. X. 2004; 69 (5)
  • Effect of chemical inhomogeneity in bismuth-based copper oxide superconductors PHYSICAL REVIEW B Eisaki, H., Kaneko, N., Feng, D. L., Damascelli, A., Mang, P. K., Shen, K. M., Shen, Z. X., Greven, M. 2004; 69 (6)
  • Angle-resolved photoemission spectral function analysis of the electron-doped cuprate Nd1.85Ce0.15CuO4 PHYSICAL REVIEW B Armitage, N. P., Lu, D. H., Kim, C., Damascelli, A., Shen, K. M., Ronning, F., Feng, D. L., Bogdanov, P., Zhou, X. J., Yang, W. L., Hussain, Z., Mang, P. K., Kaneko, N., Greven, M., Onose, Y., Taguchi, Y., Tokura, Y., Shen, Z. X. 2003; 68 (6)
  • Universal nodal Fermi velocity NATURE Zhou, X. J., Yoshida, T., Lanzara, A., Bogdanov, P. V., Kellar, S. A., Shen, K. M., Yang, W. L., Ronning, F., Sasagawa, T., Kakeshita, T., Noda, T., Eisaki, H., Uchida, S., Lin, C. T., Zhou, F., Xiong, J. W., Ti, W. X., Zhao, Z. X., Fujimori, A., Hussain, Z., Shen, Z. X. 2003; 423 (6938): 398-398

    View details for DOI 10.1038/423398a

    View details for Web of Science ID 000183012000028

  • High-temperature superconductors: Universal nodal Fermi velocity. Nature Zhou, X. J., Yoshida, T., Lanzara, A., Bogdanov, P. V., Kellar, S. A., Shen, K. M., Yang, W. L., Ronning, F., Sasagawa, T., Kakeshita, T., Noda, T., Eisaki, H., Uchida, S., Lin, C. T., Zhou, F., Xiong, J. W., Ti, W. X., Zhao, Z. X., Fujimori, A., Hussain, Z., Shen, Z. 2003; 423 (6938): 398-?

    View details for PubMedID 12761537

  • ARPES study on electronic evolution in Ca2-xNaxCuO2Cl2 PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS Sasagawa, T., Ronning, F., Kohsaka, Y., Shen, K. M., Yoshida, T., Azuma, M., Takano, M., Shen, Z. X., Takagi, H. 2003; 388: 307-308
  • Evolution of a metal to insulator transition in Ca2-xNaxCuO2Cl2 as seen by angle-resolved photoemission PHYSICAL REVIEW B Ronning, F., Sasagawa, T., Kohsaka, Y., Shen, K. M., Damascelli, A., Kim, C., Yoshida, T., Armitage, N. P., Lu, D. H., Feng, D. L., MILLER, L. L., Takagi, H., Shen, Z. X. 2003; 67 (16)
  • Photoemission studies in MgB2 PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS Uchiyama, H., Tajima, S., Shen, K. M., Lu, D. H., Shen, Z. X. 2003; 385 (1-2): 85-90
  • Universality of the electronic structure from a half-filled CuO2 plane PHYSICAL REVIEW B Ronning, F., Kim, C., Shen, K. M., Armitage, N. P., Damascelli, A., Lu, D. H., Feng, D. L., Shen, Z. X., MILLER, L. L., Kim, Y. J., Chou, F., Terasaki, I. 2003; 67 (3)
  • Anomalous momentum dependence of the quasiparticle scattering rate in overdoped Bi2Sr2CaCu2O8 PHYSICAL REVIEW LETTERS Bogdanov, P. V., Lanzara, A., Zhou, X. J., Yang, W. L., Eisaki, H., Hussain, Z., Shen, Z. X. 2002; 89 (16)

    Abstract

    The question of the anisotropy of the electron scattering in high temperature superconductors is investigated using high resolution angle-resolved photoemission data from Pb-doped Bi2Sr2CaCu2O8 (Bi2212) with suppressed superstructure. The scattering rate of low energy electrons along two bilayer-split pieces of the Fermi surface is measured (via the quasiparticle peak width), and no increase of scattering towards the antinode (pi,0) region is observed, contradicting the expectation from Q=(pi,pi) scattering. The results put a limit on the effects of Q=(pi,pi) scattering on the electronic structure of this overdoped superconductor with still very high T(c).

    View details for DOI 10.1103/PhysRevLett.89.167002

    View details for Web of Science ID 000178384300039

    View details for PubMedID 12398747

  • Doping dependence of an n-type cuprate superconductor investigated by angle-resolved photoemission spectroscopy PHYSICAL REVIEW LETTERS Armitage, N. P., Ronning, F., Lu, D. H., Kim, C., Damascelli, A., Shen, K. M., Feng, D. L., Eisaki, H., Shen, Z. X., Mang, P. K., Kaneko, N., Greven, M., Onose, Y., Taguchi, Y., Tokura, Y. 2002; 88 (25)

    Abstract

    We present an angle-resolved photoemission doping dependence study of the n-type cuprate superconductor Nd(2-x)Ce(x)CuO(4+/-delta), from the half-filled Mott insulator to the T(c) = 24 K superconductor. In Nd2CuO4, we reveal the charge-transfer band for the first time. As electrons are doped into the system, this feature's intensity decreases with the concomitant formation of near- E(F) spectral weight. At low doping, the Fermi surface is an electron-pocket (with volume approximately x) centered at (pi,0). Further doping leads to the creation of a new holelike Fermi surface (volume approximately 1+x) centered at (pi,pi). These findings shed light on the Mott gap, its doping evolution, as well as the anomalous transport properties of the n-type cuprates.

    View details for DOI 10.1103/PhysRevLett.88.257001

    View details for Web of Science ID 000176554800043

    View details for PubMedID 12097118

  • Electronic excitations near the Brillouin zone boundary of Bi2Sr2CaCu2O8+delta PHYSICAL REVIEW B Feng, D. L., Kim, C., Eisaki, H., Lu, D. H., Damascelli, A., Shen, K. M., Ronning, F., Armitage, N. P., Kaneko, N., Greven, M., Shimoyama, J., Kishio, K., Yoshizaki, R., Gu, G. D., Shen, Z. X. 2002; 65 (22)
  • Photoemission study of the intra-unit-cell coupling in a trilayer cuprate INTERNATIONAL JOURNAL OF MODERN PHYSICS B Feng, D. L., Eisaki, H., Shen, K. M., Damascelli, A., Kim, C., Lu, D. H., Shen, Z. X., Shimizu, K., Shimoyama, J. I., Kishio, K., Motoyama, N., Kaneko, N., Greven, M., Gu, G. D. 2002; 16 (11-12): 1691-1696
  • Electronic structure of MgB2 from angle-resolved photoemission spectroscopy PHYSICAL REVIEW LETTERS Uchiyama, H., Shen, K. M., Lee, S., Damascelli, A., Lu, D. H., Feng, D. L., Shen, Z. X., Tajima, S. 2002; 88 (15)

    Abstract

    The first angle-resolved photoemission spectroscopy results from MgB2 single crystals are reported. Along the GammaK and GammaM directions, we observed three distinct dispersive features approaching the Fermi energy. These can be assigned to the theoretically predicted sigma (B 2p(x,y)) and pi (B 2p(z)) bands. In addition, a small parabolic-like band is detected around the Gamma point, which can be attributed to a surface-derived state. The overall agreement between our results and the band calculations suggests that the electronic structure of MgB2 is of a conventional nature, thus implying that electron correlations are weak and may be of little importance to superconductivity in this system.

    View details for DOI 10.1103/PhysRevLett.88.157002

    View details for Web of Science ID 000174773400031

    View details for PubMedID 11955214

  • Electronic structure of the trilayer cuprate superconductor Bi2Sr2Ca2Cu3O10+delta PHYSICAL REVIEW LETTERS Feng, D. L., Damascelli, A., Shen, K. M., Motoyama, N., Lu, D. H., Eisaki, H., Shimizu, K., Shimoyama, J., Kishio, K., Kaneko, N., Greven, M., Gu, G. D., Zhou, X. J., Kim, C., Ronning, F., Armitage, N. P., Shen, Z. X. 2002; 88 (10)

    Abstract

    The low-energy electronic structure of the nearly optimally doped trilayer cuprate superconductor Bi(2)Sr(2)Ca(2)Cu(3)O(10+delta) is investigated by angle-resolved photoemission spectroscopy. The normal state quasiparticle dispersion and Fermi surface and the superconducting d-wave gap and coherence peak are observed and compared with those of single- and bilayer systems. We find that both the superconducting gap magnitude and the relative coherence-peak intensity scale linearly with T(c) for various optimally doped materials.

    View details for DOI 10.1103/PhysRevLett.88.107001

    View details for Web of Science ID 000174342000052

    View details for PubMedID 11909381

  • Surface electronic structure of Sr2RuO4 PHYSICAL REVIEW B Shen, K. M., Damascelli, A., Lu, D. H., Armitage, N. P., Ronning, F., Feng, D. L., Kim, C., Shen, Z. X., Singh, D. J., Mazin, I. I., Nakatsuji, S., Mao, Z. Q., Maeno, Y., Kimura, T., Tokura, Y. 2001; 64 (18)
  • Anomalous electronic structure and pseudogap effects in Nd1.85Ce0.15CuO4 PHYSICAL REVIEW LETTERS Armitage, N. P., Lu, D. H., Kim, C., Damascelli, A., Shen, K. M., Ronning, F., Feng, D. L., Bogdanov, P., Shen, Z. X., Onose, Y., Taguchi, Y., Tokura, Y., Mang, P. K., Kaneko, N., Greven, M. 2001; 87 (14)

    Abstract

    We report a high-resolution angle-resolved photoemission spectroscopic study of the electron-doped ( n-type) cuprate superconductor Nd1.85Ce0.15CuO4. We observe regions along the Fermi surface where the near- E(F) intensity is suppressed and the spectral features are broad in a manner reminiscent of the high-energy "pseudogap" in the underdoped p-type (hole doped) cuprates. However, instead of occurring near the (pi,0) region, as in the p-type materials, this pseudogap falls near the intersection of the underlying Fermi surface with the antiferromagnetic Brillouin zone boundary.

    View details for DOI 10.1103/PhysRevLett.87.147003

    View details for Web of Science ID 000171427500041

    View details for PubMedID 11580672

  • Evidence for ubiquitous strong electron-phonon coupling in high-temperature superconductors NATURE Lanzara, A., Bogdanov, P. V., Zhou, X. J., Kellar, S. A., Feng, D. L., Lu, E. D., Yoshida, T., Eisaki, H., Fujimori, A., Kishio, K., Shimoyama, J. I., Noda, T., Uchida, S., Hussain, Z., Shen, Z. X. 2001; 412 (6846): 510-514

    Abstract

    Coupling between electrons and phonons (lattice vibrations) drives the formation of the electron pairs responsible for conventional superconductivity. The lack of direct evidence for electron-phonon coupling in the electron dynamics of the high-transition-temperature superconductors has driven an intensive search for an alternative mechanism. A coupling of an electron with a phonon would result in an abrupt change of its velocity and scattering rate near the phonon energy. Here we use angle-resolved photoemission spectroscopy to probe electron dynamics-velocity and scattering rate-for three different families of copper oxide superconductors. We see in all of these materials an abrupt change of electron velocity at 50-80 meV, which we cannot explain by any known process other than to invoke coupling with the phonons associated with the movement of the oxygen atoms. This suggests that electron-phonon coupling strongly influences the electron dynamics in the high-temperature superconductors, and must therefore be included in any microscopic theory of superconductivity.

    View details for Web of Science ID 000170202900037

    View details for PubMedID 11484045

  • Dual nature of the electronic structure of (La2-x-yNdySrx)CuO4 and La1.85Sr0.15CuO4 PHYSICAL REVIEW LETTERS Zhou, X. J., Yoshida, T., Kellar, S. A., Bogdanov, P. V., Lu, E. D., Lanzara, A., Nakamura, M., Noda, T., Kakeshita, T., Eisaki, H., Uchida, S., Fujimora, A., Hussain, Z., Shen, Z. X. 2001; 86 (24): 5578-5581

    Abstract

    High resolution angle-resolved photoemission measurements have been carried out on (La(1.4--x)-Nd(0.6)Sr(x))CuO(4), a model system with static one-dimensional (1D) charge ordering (stripe), and (La(1.85)-Sr(0.15))CuO(4), a high temperature superconductor (T(c) = 40 K) with possible dynamic stripes. In addition to the straight segments near ( pi,0) and ( 0,pi) antinodal regions, we have identified the existence of spectral weight along the [1,1] nodal direction in the electronic structure of both systems. This observation of nodal state, together with the straight segments near antinodal regions, reveals the dual nature of the electronic structure of stripes due to the competition of order and disorder.

    View details for Web of Science ID 000169239500043

    View details for PubMedID 11415305

  • Bilayer splitting in the electronic structure of heavily overdoped Bi2Sr2CaCu2O8+delta PHYSICAL REVIEW LETTERS Feng, D. L., Armitage, N. P., Lu, D. H., Damascelli, A., Hu, J. P., Bogdanov, P., Lanzara, A., Ronning, F., Shen, K. M., Eisaki, H., Kim, C., Shen, Z. X., Shimoyama, J. I., Kishio, K. 2001; 86 (24): 5550-5553

    Abstract

    The electronic structure of heavily overdoped Bi(2)Sr(2)CaCu(2)O(8+delta) is investigated by angle-resolved photoemission spectroscopy. The long-sought bilayer band splitting in this two-plane system is observed in both normal and superconducting states, which qualitatively agrees with the bilayer Hubbard model calculations. The maximum bilayer energy splitting is about 88 meV for the normal state feature, while it is only about 20 meV for the superconducting peak.

    View details for Web of Science ID 000169239500036

    View details for PubMedID 11415298

  • Superconducting gap and strong in-plane anisotropy in untwinned YBa2Cu3O7-delta PHYSICAL REVIEW LETTERS Lu, D. H., Feng, D. L., Armitage, N. P., Shen, K. M., Damascelli, A., Kim, C., Ronning, F., Shen, Z. X., Bonn, D. A., Liang, R., Hardy, W. N., Rykov, A. I., Tajima, S. 2001; 86 (19): 4370-4373

    Abstract

    With significantly improved sample quality and instrumental resolution, we clearly identify in the ( pi,0) photoemission spectra from YBa(2)Cu(3)O(6.993), in the superconducting state, the long-sought "peak-dip-hump" structure. This advance allows us to investigate the large a-b anisotropy of the in-plane electronic structure including, in particular, a 50% difference in the magnitude of the superconducting gap that scales with the energy position of the hump feature. This anisotropy, likely induced by the presence of the CuO chains, raises serious questions about attempts to quantitatively explain the YBa(2)Cu(3)O(7-delta) data from various experiments using models based on a perfectly square lattice.

    View details for Web of Science ID 000168591000045

    View details for PubMedID 11328177

  • A photoemission investigation of the superconducting gap in an electron-doped cuprate superconductor JOURNAL OF ELECTRON SPECTROSCOPY AND RELATED PHENOMENA Armitage, N. P., Lu, D. H., Kim, C., Damascelli, A., Shen, K. M., Ronning, F., Shen, Z. X., Onose, Y., Taguchi, Y., Tokura, Y. 2001; 114: 623-627
  • Fermi surface of Sr2RuO4 from angle resolved photoemission JOURNAL OF ELECTRON SPECTROSCOPY AND RELATED PHENOMENA Damascelli, A., Shen, K. M., Lu, D. H., Armitage, N. P., Ronning, F., Feng, D. L., Kim, C., Shen, Z. X., Kimura, T., Tokura, Y., Mao, Z. Q., Maeno, Y. 2001; 114: 641-646
  • Superconducting gap anisotropy in Nd1.85Ce0.15CuO4: Results from photoemission PHYSICAL REVIEW LETTERS Armitage, N. P., Lu, D. H., Feng, D. L., Kim, C., Damascelli, A., Shen, K. M., Ronning, F., Shen, Z. X., Onose, Y., Taguchi, Y., Tokura, Y. 2001; 86 (6): 1126-1129

    Abstract

    We have performed angle resolved photoelectron spectroscopy on the electron doped cuprate superconductor Nd1.85Ce0.15CuO4. A comparison of the leading edge midpoints between the superconducting and normal states reveals a small, but finite shift of 1.5-2 meV near the ( pi,0) position, but no observable shift along the zone diagonal near ( pi/2, pi/2). This is interpreted as evidence for an anisotropic superconducting gap in the electron doped materials, which is consistent with the presence of d-wave superconducting order in this cuprate superconductor.

    View details for Web of Science ID 000166781000046

    View details for PubMedID 11178026

  • Pseudogaps and dynamical stripes in La2-xSrxCuO4 from photoemission spectroscopy JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS Fujimori, A., Ino, A., Yoshida, T., Mizokawa, T., Nakamura, M., Kim, C., Shen, Z. X., Kishio, K., Kakeshita, T., Eisaki, H., Uchida, S. 2001; 62 (1-2): 15-19
  • Fermi surface, surface states, and surface reconstruction in Sr2RuO4 PHYSICAL REVIEW LETTERS Damascelli, A., Lu, D. H., Shen, K. M., Armitage, N. P., Ronning, F., Feng, D. L., Kim, C., Shen, Z. X., Kimura, T., Tokura, Y., Mao, Z. Q., Maeno, Y. 2000; 85 (24): 5194-5197
  • ARPES features of the AF insulators Sr2CuO2Cl2 and Ca2CuO2Cl2 close to the AF zone boundary PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS Ronning, F., Kim, C., Damascelli, A., Armitage, N. P., Lu, D. H., Shen, K. M., MILLER, L. L., Kim, Y. J., Kastner, M. A., Birgeneau, R. J., Shen, Z. X. 2000; 341: 2087-2090
  • Electronic structure of Nd1.85Ce0.15CuO4: Evidence for a disparity between hole and electron doped cuprate superconductors PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS Armitage, N. P., Lu, D. H., Kim, C., Damascelli, A., Shen, K. M., Ronning, F., Onose, Y., Taguchi, Y., Tokura, Y., Shen, Z. X. 2000; 341: 2083-2086
  • On the similarity of the spectral weight pattern of Bi2Sr2CaCuO8+delta and La1.48Nd0.4Sr0.12CuO4 PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS Feng, D. L., Lu, D. H., Shen, K. M., Oh, S., Andrus, A., O'Donnell, J., Eckstein, J. N., Shimoyama, J., Kishio, K., Shen, Z. X. 2000; 341: 2097-2098
  • Signature of superfluid density in the single-particle excitation spectrum of Bi2Sr2CaCu2O8+delta SCIENCE Feng, D. L., Lu, D. H., Shen, K. M., Kim, C., Eisaki, H., Damascelli, A., Yoshizaki, R., Shimoyama, J., Kishio, K., Gu, G. D., Oh, S., Andrus, A., O'Donnell, J., Eckstein, J. N., Shen, Z. X. 2000; 289 (5477): 277-281
  • Electronic structure of mott insulators studied by inelastic X-ray scattering Science (New York, N.Y.) Hasan, M. Z., Isaacs, E. D., Shen, Z., Miller, L. L., Tsutsui, K., Tohyama, T., Maekawa, S. 2000; 288 (5472): 1811-4

    Abstract

    The electronic structure of Mott insulators continues to be a major unsolved problem in physics despite more than 50 years of research. Well-developed momentum-resolved spectroscopies such as photoemission or neutron scattering cannot probe the full Mott gap. High-resolution resonant inelastic x-ray scattering revealed dispersive charge excitations across the Mott gap in a high-critical temperature parent cuprate (Ca(2)CuO(2)Cl(2)), shedding light on the anisotropy of the Mott gap. These charge excitations across the Mott gap can be described within the framework of the Hubbard model.

    View details for PubMedID 10846160

  • Fermi surface, surface states, and surface reconstruction in Sr2RuO4 Physical review letters Damascelli, A., Lu, D. H., Shen, K. M., Armitage, N. P., Ronning, F., Feng, D. L., Kim, C., Shen, Z. X., Kimura, T., Tokura, Y., Mao, Z. Q., Maeno, Y. 2000; 85 (24): 5194-7

    Abstract

    The electronic structure of Sr2RuO4 is investigated by high angular resolution ARPES at several incident photon energies. We address the controversial issues of the Fermi surface (FS) topology and the van Hove singularity at the M point, showing that a surface state and the replica of the primary FS due to sqrt[2]xsqrt[2] surface reconstruction are responsible for previous conflicting interpretations. The FS thus determined by ARPES is consistent with the de Haas-van Alphen results, and it provides additional information on the detailed shape of the alpha, beta, and gamma sheets.

    View details for PubMedID 11102219

  • Evidence for an energy scale for quasiparticle dispersion in Bi2Sr2CaCu2O8 Physical review letters Bogdanov, P. V., Lanzara, A., Kellar, S. A., Zhou, X. J., Lu, E. D., Zheng, W. J., Gu, G., Shimoyama, J., Kishio, K., Ikeda, H., Yoshizaki, R., Hussain, Z., Shen, Z. X. 2000; 85 (12): 2581-4

    Abstract

    Quasiparticle dispersion in Bi2Sr2CaCu2O8 is investigated with improved angular resolution as a function of temperature and doping. Unlike the linear dispersion predicted by the band calculation, the data show a sharp break in dispersion at 50+/-15 meV binding energy where the velocity changes by a factor of 2 or more. This change provides an energy scale in the quasiparticle self-energy. This break in dispersion is evident at and away from the d-wave node line, but the magnitude of the dispersion change decreases with temperature and with increasing doping.

    View details for PubMedID 10978112

  • Signature of superfluid density in the single-particle excitation spectrum of Bi(2)Sr(2)CaCu(2)O(8+delta) Science (New York, N.Y.) Feng, D. L., Lu, D. H., Shen, K. M., Kim, C., Eisaki, H., Damascelli, A., Yoshizaki, R., Shimoyama, J., Kishio, K., Gu, G. D., Oh, S., Andrus, A., O'Donnell, J., Eckstein, J. N., Shen, Z. 2000; 289 (5477): 277-81

    Abstract

    We report that the doping and temperature dependence of photoemission spectra near the Brillouin zone boundary of Bi(2)Sr(2)CaCu(2)O(8+delta)exhibit unexpected sensitivity to the superfluid density. In the superconducting state, the photoemission peak intensity as a function of doping scales with the superfluid density and the condensation energy. As a function of temperature, the peak intensity shows an abrupt behavior near the superconducting phase transition temperature where phase coherence sets in, rather than near the temperature where the gap opens. This anomalous manifestation of collective effects in single-particle spectroscopy raises important questions concerning the mechanism of high-temperature superconductivity.

    View details for PubMedID 10894771

  • Fermi surface evolution in cuprates: an angle-resolved photoemission study PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS Ronning, F., Kim, C., Shen, Z. X. 1999; 317: 320-324
  • One-Dimensional Electronic Structure and Suppression of d-Wave Node State in (La(1.28)Nd(0.6)Sr(0.12))CuO(4). Science (New York, N.Y.) Zhou, X. J., Bogdanov, P., Kellar, S. A., Noda, T., Eisaki, H., Uchida, S., Hussain, Z., Shen, Z. 1999; 286 (5438): 268-272

    Abstract

    Angle-resolved photoemission spectroscopy was carried out on (La(1.28)Nd(0.6) Sr(0.12))CuO(4), a model system of the charge- and spin-ordered state, or stripe phase. The electronic structure contains characteristic features consistent with other cuprates, such as the flat band at low energy near the Brillouin zone face. However, the low-energy excitation near the expected d-wave node region is strongly suppressed. The frequency-integrated spectral weight is confined inside one-dimensional segments in the momentum space (defined by horizontal momenta &cjs3539;k(x)&cjs3539; = pi/4 and vertical momenta &cjs3539;k(y)&cjs3539; = pi/4), deviating strongly from the more rounded Fermi surface expected from band calculations. This departure from the two-dimensional Fermi surface persists to a very high energy scale. These results provide important information for establishing a theory to understand the charge and spin ordering in cuprates and their relation with high-temperature superconductivity.

    View details for PubMedID 10514366

  • Photoemission evidence for a remnant fermi surface and a d-wave-like dispersion in insulating Ca2CuO2Cl2 SCIENCE Ronning, F., Kim, C., Feng, D. L., Marshall, D. S., Loeser, A. G., MILLER, L. L., Eckstein, J. N., Bozovic, I., Shen, Z. X. 1998; 282 (5396): 2067-2072
  • Temperature-induced momentum-dependent spectral weight transfer in Bi2Sr2CaCu2O8+delta Science (New York, N.Y.) Shen, Z., White, P. J., Feng, D. L., Kim, C., Gu, G. D., Ikeda, H., Yoshizaki, R., Koshizuka, N. 1998; 280 (5361): 259-62

    Abstract

    Angle-resolved photoemission data from the cuprate superconductor Bi2Sr2CaCu2O8+delta above and below the superconducting transition temperature Tc reveal momentum-dependent changes that extend up to an energy of about 0.3 electron volt, or 40kTc (where k is the Boltzmann constant). The data suggest an anomalous transfer of spectral weight from one momentum to another, involving a sizable momentum transfer Q approximately (0.45pi, 0). The observed Q is intriguingly near the charge-order periodicity required if fluctuating charge stripes are present.

    View details for PubMedID 9535649

  • Photoemission evidence for a remnant fermi surface and a d-wave-like dispersion in insulating Ca2CuO2Cl2 Science (New York, N.Y.) Ronning, F., Kim, C., Feng, D. L., Marshall, D. S., Loeser, A. G., Miller, L. L., Eckstein, J. N., Bozovic, I., Shen, Z. 1998; 282 (5396): 2067-72

    Abstract

    An angle-resolved photoemission study is reported on Ca2CuO2Cl2, a parent compound of high-Tc superconductors. Analysis of the electron occupation probability, n(k), from the spectra shows a steep drop in spectral intensity across a contour that is close to the Fermi surface predicted by the band calculation. This analysis reveals a Fermi surface remnant, even though Ca2CuO2Cl2 is a Mott insulator. The lowest energy peak exhibits a dispersion with approximately the &cjs3539;coskxa - coskya&cjs3539; form along this remnant Fermi surface. Together with the data from Dy-doped Bi2Sr2CaCu2O8+delta, these results suggest that this d-wave-like dispersion of the insulator is the underlying reason for the pseudo gap in the underdoped regime.

    View details for PubMedID 9851925

  • Doping dependence of Bi2Sr2CaCu2O8+delta in the normal state PHYSICA C-SUPERCONDUCTIVITY AND ITS APPLICATIONS Loeser, A. G., Dessau, D. S., Shen, Z. X. 1996; 263 (1-4): 208-213
  • Excitation Gap in the Normal State of Underdoped Bi2Sr2CaCu2O8+delta Science (New York, N.Y.) Loeser, A. G., Shen, Z., Dessau, D. S., Marshall, D. S., Park, C. H., Fournier, P., Kapitulnik, A. 1996; 273 (5273): 325-9

    Abstract

    Angle-resolved photoemission experiments reveal evidence of an energy gap in the normal state excitation spectrum of the cuprate superconductor Bi2Sr2CaCu2O8+delta. This gap exists only in underdoped samples and closes around the doping level at which the superconducting transition temperature Tc is a maximum. The momentum dependence and magnitude of the gap closely resemble those of the dx2-y2 gap observed in the superconducting state. This observation is consistent with results from several other experimental techniques, which also indicate the presence of a gap in the normal state. Some possible theoretical explanations for this effect are reviewed.

    View details for PubMedID 8662512

  • FERMI SURFACES AND ENERGY GAPS OF HIGH-TEMPERATURE SUPERCONDUCTORS OXIDE SUPERCONDUCTOR PHYSICS AND NANO-ENGINEERING Shen, Z. X., Dessau, D. S. 1994; 2158: 64-69
  • SPECTRAL WEIGHT CHANGES AT THE SUPERCONDUCTING TRANSITION OF BI2SR2CACU2O8+DELTA JOURNAL OF PHYSICS AND CHEMISTRY OF SOLIDS Dessau, D. S., Shen, Z. X., Wells, B. O., SPICER, W. E., Arko, A. J. 1991; 52 (11-12): 1401-1409
  • ANGLE-RESOLVED-PHOTOEMISSION STUDY OF BI2SR2CACU2O8+DELTA - METALLICITY OF THE BI-O PLANE PHYSICAL REVIEW LETTERS Wells, B. O., Shen, Z. X., Dessau, D. S., SPICER, W. E., Olson, C. G., Mitzi, D. B., Kapitulnik, A., LIST, R. S., Arko, A. 1990; 65 (24): 3056-3059
  • PHOTOEMISSION-STUDY OF CUO AND CU2O SINGLE-CRYSTALS PHYSICAL REVIEW B Shen, Z. X., LIST, R. S., Dessau, D. S., Parmigiani, F., Arko, A. J., Bartlett, R., Wells, B. O., LINDAU, I., SPICER, W. E. 1990; 42 (13): 8081-8085
  • ELECTRONIC-STRUCTURE OF THE GOLD BI2SR2CACU2O8 AND GOLD EUBA2CU3O7-DELTA INTERFACES AS STUDIED BY PHOTOEMISSION SPECTROSCOPY APPLIED PHYSICS LETTERS Dessau, D. S., Shen, Z. X., Wells, B. O., SPICER, W. E., LIST, R. S., Arko, A. J., BARTLETT, R. J., Fisk, Z., Cheong, S. W., Mitzi, D. B., Kapitulnik, A., Schirber, J. E. 1990; 57 (3): 307-309
  • PHOTOEMISSION-STUDY OF COO PHYSICAL REVIEW B Shen, Z. X., Allen, J. W., LINDBERG, P. A., Dessau, D. S., Wells, B. O., Borg, A., Ellis, W., Kang, J. S., Oh, S. J., LINDAU, I., SPICER, W. E. 1990; 42 (3): 1817-1828
  • YB VALENCE IN YB1-XCAXAL2 PSEUDOBINARY ALLOYS VIA YB LIII X-RAY ABSORPTION-SPECTROSCOPY SOLID STATE COMMUNICATIONS Eggenhoffner, R., Sancrotti, M., ABBATI, I., Puppin, E., Shen, Z. X., LINDAU, I., Iandelli, A., Olcese, G. L. 1990; 74 (9): 1009-1012
  • YB MEAN VALENCE IN CHEMICALLY COMPRESSED YB1-XSCXAL2 PSEUDOBINARY ALLOYS - AN X-RAY ABSORPTION-SPECTROSCOPY INVESTIGATION SOLID STATE COMMUNICATIONS Sancrotti, M., ABBATI, I., Puppin, E., Shen, Z. X., LINDAU, I., Eggenhoffner, R., Iandelli, A., Olcese, G. L. 1990; 74 (10): 1131-1135
  • ASPECTS OF THE CORRELATION-EFFECTS, ANTIFERROMAGNETIC ORDER, AND TRANSLATIONAL SYMMETRY OF THE ELECTRONIC-STRUCTURE OF NIO AND COO PHYSICAL REVIEW LETTERS Shen, Z. X., Shih, C. K., JEPSEN, O., SPICER, W. E., LINDAU, I., Allen, J. W. 1990; 64 (20): 2442-2445
  • NATURE OF THE VALENCE BAND STATES IN BI2(CA,SR,LA)3CU2O8 HIGH TC SUPERCONDUCTING THIN FILMS : PROCESSING, CHARACTERIZATION, AND APPLICATIONS Wells, B. O., LINDBERG, P. A., Shen, Z. X., Dessau, D. S., SPICER, W. E., LINDAU, I., Mitzi, D. B., Kapitulnik, A. 1990; 200: 36-41
  • PHOTOEMISSION-STUDIES OF HIGH-TEMPERATURE SUPERCONDUCTORS SURFACE SCIENCE REPORTS LINDBERG, P. A., Shen, Z. X., SPICER, W. E., LINDAU, I. 1990; 11 (1-4): 1-?
  • PHOTOEMISSION-STUDY OF ABSORPTION MECHANISMS IN BI2.0SR1.8CA0.8LA0.3CU2.1O8+DELTA, BABIO3, AND ND1.85CE0.15CUO4 PHYSICAL REVIEW B LINDBERG, P. A., Shen, Z. X., Wells, B. O., Dessau, D. S., Ellis, W. P., Borg, A., Kang, J. S., Mitzi, D. B., LINDAU, I., SPICER, W. E., Kapitulnik, A. 1989; 40 (13): 8840-8843
  • PHOTOEMISSION-STUDY OF THE ELECTRONIC-STRUCTURE (PR0.2LA0.8)(BA1.875LA0.125)CU3O7-DELTA SYSTEM SOLID STATE COMMUNICATIONS LINDBERG, P. A., Shen, Z. X., LINDAU, I., SPICER, W. E., Mitzi, D. B., Kapitulnik, A. 1989; 72 (6): 575-578
  • ELECTRONIC-STRUCTURE OF CLEAN AND AG-COVERED SINGLE-CRYSTALLINE BI2SR2CUO6 PHYSICAL REVIEW B LINDBERG, P. A., Shen, Z. X., Wells, B. O., Mitzi, D. B., LINDAU, I., SPICER, W. E., Kapitulnik, A. 1989; 40 (13): 8769-8773
  • ELECTRONIC-STRUCTURE OF PB2SR2PRCU3O8 AS STUDIED BY RESONANT PHOTOEMISSION SPECTROSCOPY PHYSICAL REVIEW B Dessau, D. S., Shen, Z. X., LINDBERG, P. A., Wells, B. O., Borg, A., LINDAU, I., SPICER, W. E., Waszczak, J. V., Schneemeyer, L. F. 1989; 40 (10): 6726-6730
  • PHOTOEMISSION-STUDY OF MONOCLINIC BABIO3 PHYSICAL REVIEW B Shen, Z. X., LINDBERG, P. A., Wells, B. O., Dessau, D. S., Borg, A., LINDAU, I., SPICER, W. E., Ellis, W. P., Kwei, G. H., Ott, K. C., Kang, J. S., Allen, J. W. 1989; 40 (10): 6912-6918
  • SPECTROSCOPIC EVIDENCE OF TWO-DIMENSIONAL CHARACTER OF THE 90-K BI2(SR,LA,CA)3CU2O8 SUPERCONDUCTORS APPLIED PHYSICS LETTERS LINDBERG, P. A., Shen, Z. X., Wells, B. O., Dessau, D. S., Borg, A., LINDAU, I., SPICER, W. E., Mitzi, D. B., Kapitulnik, A. 1989; 55 (11): 1141-1143
  • THE ELECTRONIC-STRUCTURE OF BI2.0SR1.8LA0.3CA0.8CU2.1O8+DELTA-SUPERCONDUCTORS STUDIED USING ULTRAVIOLET AND X-RAY PHOTOELECTRON-SPECTROSCOPY PHYSICA C LINDBERG, P. A., Shen, Z. X., Dessau, D. S., Wells, B. O., Borg, A., Ellis, W., Mitzi, D. B., LINDAU, I., SPICER, W. E., Kapitulnik, A. 1989; 159 (5): 649-653
  • ELECTRONIC-STRUCTURE OF THE QUENCHED SUPERCONDUCTIVITY MATERIALS Y1-XPRXBA2CU3O7-DELTA JOURNAL OF THE LESS-COMMON METALS Kang, J. S., Allen, J. W., Shen, Z. X., Ellis, W. P., Yeh, J. J., Lee, B. W., Maple, M. B., SPICER, W. E., LINDAU, I. 1989; 148 (1-2): 121-132
  • PHOTOELECTRON ENERGY-LOSS STUDY OF THE BI2CASR2CU2O8 SUPERCONDUCTOR PHYSICAL REVIEW B Shen, Z. X., LINDBERG, P. A., Dessau, D. S., LINDAU, I., SPICER, W. E., Mitzi, D. B., Bozovic, I., Kapitulnik, A. 1989; 39 (7): 4295-4298
  • ELECTRONIC-STRUCTURE OF THE LA1+XBA2-XCU3O7+DELTA-SYSTEM STUDIED BY PHOTOELECTRON-SPECTROSCOPY SOLID STATE COMMUNICATIONS LINDBERG, P. A., Shen, Z. X., Hwang, J., Shih, C. K., LINDAU, I., SPICER, W. E., Mitzi, D. B. 1989; 69 (1): 27-31
  • SURFACE-STRUCTURE OF BI2SR2CACU2O8+SIGMA HIGH-TEMPERATURE SUPERCONDUCTORS STUDIED USING LOW-ENERGY ELECTRON-DIFFRACTION APPLIED PHYSICS LETTERS LINDBERG, P. A., Shen, Z. X., Wells, B. O., Mitzi, D. B., LINDAU, I., SPICER, W. E., Kapitulnik, A. 1988; 53 (25): 2563-2565
  • ELECTRONIC-STRUCTURE OF CERAMICS AND THIN-FILM SAMPLES OF HIGH-TC BI2SR2CACU2O8+DELTA SUPERCONDUCTORS - EFFECTS OF AR+ SPUTTERING, O-2 EXPOSURE, AND RB DEPOSITION APPLIED PHYSICS LETTERS LINDBERG, P. A., Soukiassian, P., Shen, Z. X., Shah, S. I., Eom, C. B., LINDAU, I., SPICER, W. E., Geballe, T. H. 1988; 53 (20): 1970-1972
  • KAPPA-RESOLVED ALLOY BOWING IN PSEUDOBINARY INXGA1-XAS ALLOYS PHYSICAL REVIEW LETTERS Hwang, J., Pianetta, P., Pao, Y. C., Shih, C. K., Shen, Z. X., LINDBERG, P. A., Chow, R. 1988; 61 (7): 877-880
  • PHOTOEMISSION-STUDY OF THE SURFACE ELECTRONIC-STRUCTURE OF BI-CA-SR-CU-O SUPERCONDUCTORS MODIFIED BY NE SPUTTERING, AG DEPOSITION, AND HEAT-TREATMENT APPLIED PHYSICS LETTERS LINDBERG, P. A., Shen, Z. X., LINDAU, I., SPICER, W. E., Eom, C. B., Geballe, T. H. 1988; 53 (6): 529-531
  • PHOTOEMISSION FROM THE SI/LA INTERFACE SOLID STATE COMMUNICATIONS Puppin, E., Guyot, H., Shen, Z. X., Hwang, J., LINDAU, I. 1988; 67 (1): 23-27
  • THE EFFECT OF STRAIN ON THE BAND-STRUCTURE OF INXGA1-XAS JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B Hwang, J., Pianetta, P., Kubiak, G. D., Stulen, R. H., Shin, C. K., Pao, Y. C., Shen, Z. X., LINDBERG, P. A., Chow, R. 1988; 6 (4): 1234-1239
  • ANDERSON HAMILTONIAN DESCRIPTION OF THE EXPERIMENTAL ELECTRONIC-STRUCTURE AND MAGNETIC-INTERACTIONS OF COPPER-OXIDE SUPERCONDUCTORS PHYSICAL REVIEW B Shen, Z. X., Allen, J. W., Yeh, J. J., Kang, J. S., Ellis, W., Spicer, W., LINDAU, I., Maple, M. B., DALICHAOUCH, Y. D., Torikachvili, M. S., Sun, J. Z., Geballe, T. H. 1987; 36 (16): 8414-8428
  • A PHOTOEMISSION-STUDY OF THE SI(111)/GD INTERFACE - A COMPARISON WITH THE BULK SILICIDES JOURNAL OF VACUUM SCIENCE & TECHNOLOGY B Puppin, E., Nogami, J., Carbone, C., Shen, Z. X., LINDAU, I., Pate, B. B., ABBATI, I., Braicovich, L. 1987; 5 (4): 1083-1086

Conference Proceedings


  • LOW-IMPEDANCE SHIELDED TIP PIEZORESISTIVE PROBE ENABLES PORTABLE MICROWAVE IMPEDANCE MICROSCOPY Haemmerli, A. J., Nielsen, R. T., Kundhikanjana, W., HARJEE, N., Lai, K., Yang, Y. L., Goldhaber-Gordon, D., Shen, Z. X., Pruitt, B. L. IEEE. 2012
  • Puzzles about 1/8 magic doping in cuprate Feng, D. L., Shen, Z. X., Zhou, X. J., Shen, K. M., Lu, D. H., van der Marel, D. PERGAMON-ELSEVIER SCIENCE LTD. 2006: 198-200
  • Normal state spectral lineshapes of nodal quasiparticles in single layer Bi2201 superconductor Lanzara, A., Bogdanov, P. V., Zhou, X. J., Kaneko, N., Eisaki, H., Greven, M., Hussain, Z., Shen, Z. X. PERGAMON-ELSEVIER SCIENCE LTD. 2006: 239-243
  • Evolution of the electronic structure with doping in Bi2Sr2CaCu2O8+delta - Angle resolved photoemission results Dessau, D. S., Marshall, D. S., Loeser, A. G., Park, C. H., Matsuura, A. Y., Shen, Z. X., Fournier, P., Kapitulnik, A., Kishio, K., Eckstein, J., Bozovic, I. ELSEVIER SCIENCE BV. 1996: 167-170
  • THE GOLD HIGH-TEMPERATURE SUPERCONDUCTOR INTERFACE - METALLICITY OF THE NEAR-SURFACE REGION AND A SEARCH FOR THE PROXIMITY EFFECT Dessau, D. S., Shen, Z. X., Wells, B. O., SPICER, W. E., LIST, R. S., Arko, A. J., BARTLETT, R. J., Olson, C. G., Mitzi, D. B., Eom, C. B., Kapitulnik, A., Geballe, T. H. AMER INST PHYSICS. 1991: 383-389
  • ELECTRON-SPECTROSCOPY OF HEAVY-FERMION MATERIALS Allen, J. W., Kang, J. S., Liu, L. Z., Gunnarsson, O., Christensen, N. E., Andersen, O. K., Maple, M. B., Torikachvili, M. S., Koelling, D. D., Ellis, W. P., Pate, B. B., Shen, Z. X., Yeh, J. J., LINDAU, I. IOP PUBLISHING LTD. 1990: 232-238
  • ELECTRONIC-STRUCTURE OF SINGLE CRYSTALLINE BI2(SR,CA,LA)3CU2O8 LINDBERG, P. A., Shen, Z. X., Dessau, D. S., Wells, B. O., Borg, A., Mitzi, D. B., LINDAU, I., SPICER, W. E., Kapitulnik, A. ELSEVIER SCIENCE BV. 1989: 1313-1314
  • THE ELECTRONIC-STRUCTURE OF PB2SR2PRCU3O8 AS STUDIED BY RESONANT PHOTOEMISSION SPECTROSCOPY Dessau, D. S., Shen, Z. X., LINDBERG, P. A., Wells, B. O., Borg, A., LINDAU, I., SPICER, W. E., Waszczak, J. V., Schneemeyer, L. F. ELSEVIER SCIENCE BV. 1989: 1373-1374
  • ANGLE-RESOLVED PHOTOEMISSION-STUDY OF NIO AND COO Shen, Z. X., LINDBERG, P. A., Shih, C. K., SPICER, W. E., LINDAU, I. ELSEVIER SCIENCE BV. 1989: 1311-1312