1
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Stühler R, Kowalewski A, Reis F, Jungblut D, Dominguez F, Scharf B, Li G, Schäfer J, Hankiewicz EM, Claessen R. Effective lifting of the topological protection of quantum spin Hall edge states by edge coupling. Nat Commun 2022; 13:3480. [PMID: 35710903 PMCID: PMC9203811 DOI: 10.1038/s41467-022-30996-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Accepted: 05/23/2022] [Indexed: 11/30/2022] Open
Abstract
The scientific interest in two-dimensional topological insulators (2D TIs) is currently shifting from a more fundamental perspective to the exploration and design of novel functionalities. Key concepts for the use of 2D TIs in spintronics are based on the topological protection and spin-momentum locking of their helical edge states. In this study we present experimental evidence that topological protection can be (partially) lifted by pairwise coupling of 2D TI edges in close proximity. Using direct wave function mapping via scanning tunneling microscopy/spectroscopy (STM/STS) we compare isolated and coupled topological edges in the 2D TI bismuthene. The latter situation is realized by natural lattice line defects and reveals distinct quasi-particle interference (QPI) patterns, identified as electronic Fabry-Pérot resonator modes. In contrast, free edges show no sign of any single-particle backscattering. These results pave the way for novel device concepts based on active control of topological protection through inter-edge hybridization for, e.g., electronic Fabry-Pérot interferometry. New functionalities of two-dimensional topological insulators (2DTI) are of current scientific interest. Here, the authors show that topological protection can be lifted by pairwise coupling of 2DTI bismuthene edges in close proximity.
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Affiliation(s)
- R Stühler
- Physikalisches Institut and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, D-97074, Würzburg, Germany.
| | - A Kowalewski
- Physikalisches Institut and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, D-97074, Würzburg, Germany
| | - F Reis
- Physikalisches Institut and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, D-97074, Würzburg, Germany
| | - D Jungblut
- Institut für Theoretische Physik und Astrophysik and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, D-97074, Würzburg, Germany
| | - F Dominguez
- Institut für Theoretische Physik und Astrophysik and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, D-97074, Würzburg, Germany.,Institute for Mathematical Physics, TU Braunschweig, 38106, Braunschweig, Germany
| | - B Scharf
- Institut für Theoretische Physik und Astrophysik and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, D-97074, Würzburg, Germany
| | - G Li
- Institut für Theoretische Physik und Astrophysik and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, D-97074, Würzburg, Germany.,School of Physical Science and Technology, ShanghaiTech University, 201210, Shanghai, China.,ShanghaiTech Laboratory for Topological Physics, 200031, Shanghai, China
| | - J Schäfer
- Physikalisches Institut and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, D-97074, Würzburg, Germany
| | - E M Hankiewicz
- Institut für Theoretische Physik und Astrophysik and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, D-97074, Würzburg, Germany
| | - R Claessen
- Physikalisches Institut and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, D-97074, Würzburg, Germany.
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2
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Adler F, Rachel S, Laubach M, Maklar J, Fleszar A, Schäfer J, Claessen R. Correlation-Driven Charge Order in a Frustrated Two-Dimensional Atom Lattice. Phys Rev Lett 2019; 123:086401. [PMID: 31491220 DOI: 10.1103/physrevlett.123.086401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/08/2019] [Revised: 05/10/2019] [Indexed: 06/10/2023]
Abstract
We thoroughly examine the ground state of the triangular lattice of Pb on Si(111) using scanning tunneling microscopy and spectroscopy. We detect electronic charge order, and disentangle this contribution from the atomic configuration which we find to be 1-down-2-up, contrary to previous predictions from density functional theory. Applying an extended variational cluster approach we map out the phase diagram as a function of local and nonlocal Coulomb interactions. Comparing the experimental data with the theoretical modeling leads us to conclude that electron correlations are the driving force of the charge-ordered state in Pb/Si(111). These results resolve the discussion about the origin of the well-known 3×3 reconstruction. By exploiting the tunability of correlation strength, hopping parameters, and band filling, this material class represents a promising platform to search for exotic states of matter, in particular, for chiral topological superconductivity.
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Affiliation(s)
- F Adler
- Physikalisches Institut and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, D-97074 Würzburg, Germany
| | - S Rachel
- School of Physics, University of Melbourne, Parkville, VIC 3010, Australia
- Institut für Theoretische Physik, Technische Universität Dresden, D-01069 Dresden, Germany
| | - M Laubach
- Institut für Theoretische Physik, Technische Universität Dresden, D-01069 Dresden, Germany
| | - J Maklar
- Physikalisches Institut and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, D-97074 Würzburg, Germany
| | - A Fleszar
- Institut für Theoretische Physik und Astrophysik, Universität Würzburg, D-97074 Würzburg, Germany
| | - J Schäfer
- Physikalisches Institut and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, D-97074 Würzburg, Germany
| | - R Claessen
- Physikalisches Institut and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, D-97074 Würzburg, Germany
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3
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Schlueter C, Gloskovskii A, Ederer K, Piec S, Sing M, Claessen R, Wiemann C, Schneider C, Medjanik K, Schönhense G, Amann P, Nilsson A, Drube W. New HAXPES Applications at PETRA III. ACTA ACUST UNITED AC 2018. [DOI: 10.1080/08940886.2018.1483656] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
Affiliation(s)
- C. Schlueter
- Photon Science, Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany
| | - A. Gloskovskii
- Photon Science, Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany
| | - K. Ederer
- Photon Science, Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany
| | - S. Piec
- Photon Science, Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany
| | - M. Sing
- Physikalisches Institut and Röntgen Center for Complex Materials Systems, Universität Würzburg, Würzburg, Germany
| | - R. Claessen
- Physikalisches Institut and Röntgen Center for Complex Materials Systems, Universität Würzburg, Würzburg, Germany
| | - C. Wiemann
- Peter Grünberg Institut, Jülich, Germany
| | | | - K. Medjanik
- Institut für Physik, Johannes Gutenberg-Universität, Mainz, Germany
| | - G. Schönhense
- Institut für Physik, Johannes Gutenberg-Universität, Mainz, Germany
| | - P. Amann
- Department of Physics, AlbaNova University Center, Stockholm University, Stockholm, Sweden
| | - A. Nilsson
- Department of Physics, AlbaNova University Center, Stockholm University, Stockholm, Sweden
| | - W. Drube
- Photon Science, Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany
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4
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Hogan C, Speiser E, Chandola S, Suchkova S, Aulbach J, Schäfer J, Meyer S, Claessen R, Esser N. Controlling the Local Electronic Properties of Si(553)-Au through Hydrogen Doping. Phys Rev Lett 2018; 120:166801. [PMID: 29756924 DOI: 10.1103/physrevlett.120.166801] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2017] [Revised: 11/12/2017] [Indexed: 06/08/2023]
Abstract
We propose a quantitative and reversible method for tuning the charge localization of Au-stabilized stepped Si surfaces by site-specific hydrogenation. This is demonstrated for Si(553)-Au as a model system by combining density functional theory simulations and reflectance anisotropy spectroscopy experiments. We find that controlled H passivation is a two-step process: step-edge adsorption drives excess charge into the conducting metal chain "reservoir" and renders it insulating, while surplus H recovers metallic behavior. Our approach illustrates a route towards microscopic manipulation of the local surface charge distribution and establishes a reversible switch of site-specific chemical reactivity and magnetic properties on vicinal surfaces.
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Affiliation(s)
- C Hogan
- Istituto di Struttura della Materia-CNR (ISM-CNR), via Fosso del Cavaliere 100, 00133 Rome, Italy
- Dipartimento di Fisica, Università di Roma "Tor Vergata", Via della Ricerca Scientifica 1, 00133 Roma, Italy
| | - E Speiser
- Leibniz-Institut für Analytische Wissenschaften - ISAS - e.V., Schwarzschildstraße 8, 12489 Berlin, Germany
| | - S Chandola
- Leibniz-Institut für Analytische Wissenschaften - ISAS - e.V., Schwarzschildstraße 8, 12489 Berlin, Germany
| | - S Suchkova
- Leibniz-Institut für Analytische Wissenschaften - ISAS - e.V., Schwarzschildstraße 8, 12489 Berlin, Germany
| | - J Aulbach
- Physikalisches Institut and Röntgen Center for Complex Material Systems (RCCM), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - J Schäfer
- Physikalisches Institut and Röntgen Center for Complex Material Systems (RCCM), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - S Meyer
- Physikalisches Institut and Röntgen Center for Complex Material Systems (RCCM), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - R Claessen
- Physikalisches Institut and Röntgen Center for Complex Material Systems (RCCM), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - N Esser
- Leibniz-Institut für Analytische Wissenschaften - ISAS - e.V., Schwarzschildstraße 8, 12489 Berlin, Germany
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5
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Schütz P, Di Sante D, Dudy L, Gabel J, Stübinger M, Kamp M, Huang Y, Capone M, Husanu MA, Strocov VN, Sangiovanni G, Sing M, Claessen R. Dimensionality-Driven Metal-Insulator Transition in Spin-Orbit-Coupled SrIrO_{3}. Phys Rev Lett 2017; 119:256404. [PMID: 29303315 DOI: 10.1103/physrevlett.119.256404] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2017] [Indexed: 05/27/2023]
Abstract
Upon reduction of the film thickness we observe a metal-insulator transition in epitaxially stabilized, spin-orbit-coupled SrIrO_{3} ultrathin films. By comparison of the experimental electronic dispersions with density functional theory at various levels of complexity we identify the leading microscopic mechanisms, i.e., a dimensionality-induced readjustment of octahedral rotations, magnetism, and electronic correlations. The astonishing resemblance of the band structure in the two-dimensional limit to that of bulk Sr_{2}IrO_{4} opens new avenues to unconventional superconductivity by "clean" electron doping through electric field gating.
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Affiliation(s)
- P Schütz
- Physikalisches Institut and Röntgen Center for Complex Material Systems (RCCM), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - D Di Sante
- Institut für Theoretische Physik und Astrophysik, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - L Dudy
- Physikalisches Institut and Röntgen Center for Complex Material Systems (RCCM), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - J Gabel
- Physikalisches Institut and Röntgen Center for Complex Material Systems (RCCM), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - M Stübinger
- Physikalisches Institut and Röntgen Center for Complex Material Systems (RCCM), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - M Kamp
- Physikalisches Institut and Röntgen Center for Complex Material Systems (RCCM), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Y Huang
- Van der Waals-Zeeman Insitute, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - M Capone
- CNR-IOM-Democritos National Simulation Centre and International School for Advanced Studies (SISSA), Via Bonomea 265, I-34136 Trieste, Italy
| | - M-A Husanu
- National Institute of Materials Physics, Atomistilor 405 A, 077125 Magurele, Romania
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - V N Strocov
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen, Switzerland
| | - G Sangiovanni
- Institut für Theoretische Physik und Astrophysik, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - M Sing
- Physikalisches Institut and Röntgen Center for Complex Material Systems (RCCM), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - R Claessen
- Physikalisches Institut and Röntgen Center for Complex Material Systems (RCCM), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
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6
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Dudy L, Aulbach J, Wagner T, Schäfer J, Claessen R. One-dimensional quantum matter: gold-induced nanowires on semiconductor surfaces. J Phys Condens Matter 2017; 29:433001. [PMID: 28915127 DOI: 10.1088/1361-648x/aa852a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Interacting electrons confined to only one spatial dimension display a wide range of unusual many-body quantum phenomena, ranging from Peierls instabilities to the breakdown of the canonical Fermi liquid paradigm to even unusual spin phenomena. The underlying physics is not only of tremendous fundamental interest, but may also have bearing on device functionality in future micro- and nanoelectronics with lateral extensions reaching the atomic limit. Metallic adatoms deposited on semiconductor surfaces may form self-assembled atomic nanowires, thus representing highly interesting and well-controlled solid-state realizations of such 1D quantum systems. Here we review experimental and theoretical investigations on a few selected prototypical nanowire surface systems, specifically Ge(0 0 1)-Au and Si(hhk)-Au, and the search for 1D quantum states in them. We summarize the current state of research and identify open questions and issues.
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Affiliation(s)
- L Dudy
- Physikalisches Institut and Röntgen Center for Complex Material Systems (RCCM), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
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7
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Reis F, Li G, Dudy L, Bauernfeind M, Glass S, Hanke W, Thomale R, Schäfer J, Claessen R. Bismuthene on a SiC substrate: A candidate for a high-temperature quantum spin Hall material. Science 2017; 357:287-290. [PMID: 28663438 DOI: 10.1126/science.aai8142] [Citation(s) in RCA: 278] [Impact Index Per Article: 39.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2016] [Revised: 12/16/2016] [Accepted: 06/09/2017] [Indexed: 11/02/2022]
Abstract
Quantum spin Hall materials hold the promise of revolutionary devices with dissipationless spin currents but have required cryogenic temperatures owing to small energy gaps. Here we show theoretically that a room-temperature regime with a large energy gap may be achievable within a paradigm that exploits the atomic spin-orbit coupling. The concept is based on a substrate-supported monolayer of a high-atomic number element and is experimentally realized as a bismuth honeycomb lattice on top of the insulating silicon carbide substrate SiC(0001). Using scanning tunneling spectroscopy, we detect a gap of ~0.8 electron volt and conductive edge states consistent with theory. Our combined theoretical and experimental results demonstrate a concept for a quantum spin Hall wide-gap scenario, where the chemical potential resides in the global system gap, ensuring robust edge conductance.
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Affiliation(s)
- F Reis
- Physikalisches Institut and Röntgen Research Center for Complex Material Systems, Universität Würzburg, D-97074 Würzburg, Germany
| | - G Li
- School of Physical Science and Technology, ShanghaiTech University, Shanghai 201210, China.,Institut für Theoretische Physik und Astrophysik, Universität Würzburg, D-97074 Würzburg, Germany
| | - L Dudy
- Physikalisches Institut and Röntgen Research Center for Complex Material Systems, Universität Würzburg, D-97074 Würzburg, Germany
| | - M Bauernfeind
- Physikalisches Institut and Röntgen Research Center for Complex Material Systems, Universität Würzburg, D-97074 Würzburg, Germany
| | - S Glass
- Physikalisches Institut and Röntgen Research Center for Complex Material Systems, Universität Würzburg, D-97074 Würzburg, Germany
| | - W Hanke
- Institut für Theoretische Physik und Astrophysik, Universität Würzburg, D-97074 Würzburg, Germany
| | - R Thomale
- Institut für Theoretische Physik und Astrophysik, Universität Würzburg, D-97074 Würzburg, Germany
| | - J Schäfer
- Physikalisches Institut and Röntgen Research Center for Complex Material Systems, Universität Würzburg, D-97074 Würzburg, Germany.
| | - R Claessen
- Physikalisches Institut and Röntgen Research Center for Complex Material Systems, Universität Würzburg, D-97074 Würzburg, Germany
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8
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Abstract
High-index surfaces of silicon with adsorbed gold can reconstruct to form highly ordered linear step arrays. These steps take the form of a narrow strip of graphitic silicon. In some cases--specifically, for Si(553)-Au and Si(557)-Au--a large fraction of the silicon atoms at the exposed edge of this strip are known to be spin-polarized and charge-ordered along the edge. The periodicity of this charge ordering is always commensurate with the structural periodicity along the step edge and hence leads to highly ordered arrays of local magnetic moments that can be regarded as "spin chains." Here, we demonstrate theoretically as well as experimentally that the closely related Si(775)-Au surface has--despite its very similar overall structure--zero spin polarization at its step edge. Using a combination of density-functional theory and scanning tunneling microscopy, we propose an electron-counting model that accounts for these differences. The model also predicts that unintentional defects and intentional dopants can create local spin moments at Si(hhk)-Au step edges. We analyze in detail one of these predictions and verify it experimentally. This finding opens the door to using techniques of surface chemistry and atom manipulation to create and control silicon spin chains.
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Affiliation(s)
- J Aulbach
- Physikalisches Institut and Röntgen Center for Complex Material Systems (RCCM), Universität Würzburg , D-97074 Würzburg, Germany
| | - S C Erwin
- Center for Computational Materials Science, Naval Research Laboratory , Washington, DC 20375, United States
| | - R Claessen
- Physikalisches Institut and Röntgen Center for Complex Material Systems (RCCM), Universität Würzburg , D-97074 Würzburg, Germany
| | - J Schäfer
- Physikalisches Institut and Röntgen Center for Complex Material Systems (RCCM), Universität Würzburg , D-97074 Würzburg, Germany
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9
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Kleibeuker JE, Zhong Z, Nishikawa H, Gabel J, Müller A, Pfaff F, Sing M, Held K, Claessen R, Koster G, Rijnders G. Electronic reconstruction at the isopolar LaTiO(3)/LaFeO(3) interface: an X-ray photoemission and density-functional theory study. Phys Rev Lett 2014; 113:237402. [PMID: 25526156 DOI: 10.1103/physrevlett.113.237402] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/14/2014] [Indexed: 06/04/2023]
Abstract
We report the formation of a nonmagnetic band insulator at the isopolar interface between the antiferromagnetic Mott-Hubbard insulator LaTiO_{3} and the antiferromagnetic charge transfer insulator LaFeO_{3}. By density-functional theory calculations, we find that the formation of this interface state is driven by the combination of O band alignment and crystal field splitting energy of the t_{2g} and e_{g} bands. As a result of these two driving forces, the Fe 3d bands rearrange and electrons are transferred from Ti to Fe. This picture is supported by x-ray photoelectron spectroscopy, which confirms the rearrangement of the Fe 3d bands and reveals an unprecedented charge transfer up to 1.2±0.2 e^{-}/interface unit cell in our LaTiO_{3}/LaFeO_{3} heterostructures.
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Affiliation(s)
- J E Kleibeuker
- Faculty of Science and Technology and MESA+Institute for Nanotechnology, University of Twente, 7500 AE Enschede, Netherlands and Physikalisches Institut, University of Würzburg, 97074 Würzburg, Germany
| | - Z Zhong
- Institute of Solid State Physics, Vienna University of Technology, A-1040 Vienna, Austria
| | - H Nishikawa
- Faculty of Biology-Oriented Science and Technology, Kinki University, Kinokawa 649-6493, Japan
| | - J Gabel
- Physikalisches Institut, University of Würzburg, 97074 Würzburg, Germany
| | - A Müller
- Physikalisches Institut, University of Würzburg, 97074 Würzburg, Germany
| | - F Pfaff
- Physikalisches Institut, University of Würzburg, 97074 Würzburg, Germany
| | - M Sing
- Physikalisches Institut, University of Würzburg, 97074 Würzburg, Germany
| | - K Held
- Institute of Solid State Physics, Vienna University of Technology, A-1040 Vienna, Austria
| | - R Claessen
- Physikalisches Institut, University of Würzburg, 97074 Würzburg, Germany
| | - G Koster
- Faculty of Science and Technology and MESA+Institute for Nanotechnology, University of Twente, 7500 AE Enschede, Netherlands
| | - G Rijnders
- Faculty of Science and Technology and MESA+Institute for Nanotechnology, University of Twente, 7500 AE Enschede, Netherlands
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10
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Barfuss A, Dudy L, Scholz MR, Roth H, Höpfner P, Blumenstein C, Landolt G, Dil JH, Plumb NC, Radovic M, Bostwick A, Rotenberg E, Fleszar A, Bihlmayer G, Wortmann D, Li G, Hanke W, Claessen R, Schäfer J. Elemental topological insulator with tunable Fermi level: strained α-Sn on InSb(001). Phys Rev Lett 2013; 111:157205. [PMID: 24160626 DOI: 10.1103/physrevlett.111.157205] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2013] [Indexed: 05/20/2023]
Abstract
We report on the epitaxial fabrication and electronic properties of a topological phase in strained α-Sn on InSb. The topological surface state forms in the presence of an unusual band order not based on direct spin-orbit coupling, as shown in density functional and GW slab-layer calculations. Angle-resolved photoemission including spin detection probes experimentally how the topological spin-polarized state emerges from the second bulk valence band. Moreover, we demonstrate the precise control of the Fermi level by dopants.
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Affiliation(s)
- A Barfuss
- Physikalisches Institut und Röntgen Center for Complex Materials Systems, Universität Würzburg, 97074 Würzburg, Germany
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11
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Aulbach J, Schäfer J, Erwin SC, Meyer S, Loho C, Settelein J, Claessen R. Evidence for long-range spin order instead of a Peierls transition in si(553)-Au chains. Phys Rev Lett 2013; 111:137203. [PMID: 24116812 DOI: 10.1103/physrevlett.111.137203] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/06/2013] [Indexed: 06/02/2023]
Abstract
Stabilization of the Si(553) surface by Au adsorption results in two different atomically defined chain types, one of Au atoms and one of Si. At low temperature these chains develop two- and threefold periodicity, respectively, previously attributed to Peierls instabilities. Here we report evidence from scanning tunneling microscopy that rules out this interpretation. The ×3 superstructure of the Si chains vanishes for low tunneling bias, i.e., close the Fermi level. In addition, the Au chains remain metallic despite their period doubling. Both observations are inconsistent with a Peierls mechanism. On the contrary, our results are in excellent, detailed agreement with the Si(553)-Au ground state predicted by density-functional theory, where the ×2 periodicity of the Au chain is an inherent structural feature and every third Si atom is spin polarized.
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Affiliation(s)
- J Aulbach
- Physikalisches Institut and Röntgen Center for Complex Materials Systems (RCCM), Universität Würzburg, D-97074 Würzburg, Germany
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12
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Berner G, Sing M, Fujiwara H, Yasui A, Saitoh Y, Yamasaki A, Nishitani Y, Sekiyama A, Pavlenko N, Kopp T, Richter C, Mannhart J, Suga S, Claessen R. Direct k-space mapping of the electronic structure in an oxide-oxide interface. Phys Rev Lett 2013; 110:247601. [PMID: 25165961 DOI: 10.1103/physrevlett.110.247601] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2013] [Indexed: 06/03/2023]
Abstract
The interface between LaAlO(3) and SrTiO(3) hosts a two-dimensional electron system of itinerant carriers, although both oxides are band insulators. Interface ferromagnetism coexisting with superconductivity has been found and attributed to local moments. Experimentally, it has been established that Ti 3d electrons are confined to the interface. Using soft x-ray angle-resolved resonant photoelectron spectroscopy we have directly mapped the interface states in k space. Our data demonstrate a charge dichotomy. A mobile fraction contributes to Fermi surface sheets, whereas a localized portion at higher binding energies is tentatively attributed to electrons trapped by O vacancies in the SrTiO(3). While photovoltage effects in the polar LaAlO(3) layers cannot be excluded, the apparent absence of surface-related Fermi surface sheets could also be fully reconciled in a recently proposed electronic reconstruction picture where the built-in potential in the LaAlO(3) is compensated by surface O vacancies serving also as a charge reservoir.
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Affiliation(s)
- G Berner
- Physikalisches Institut and Röntgen Center for Complex Materials Systems (RCCM), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - M Sing
- Physikalisches Institut and Röntgen Center for Complex Materials Systems (RCCM), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - H Fujiwara
- Division of Materials Physics, Graduate School of Engineering Science, Osaka University, Osaka 560-8531, Japan
| | - A Yasui
- Condensed Matter Science Division, Japan Atomic Energy Agency, SPring-8, Hyogo 679-5148, Japan
| | - Y Saitoh
- Condensed Matter Science Division, Japan Atomic Energy Agency, SPring-8, Hyogo 679-5148, Japan
| | - A Yamasaki
- Faculty of Science and Engineering, Konan University, Kobe 658-8501, Japan
| | - Y Nishitani
- Faculty of Science and Engineering, Konan University, Kobe 658-8501, Japan
| | - A Sekiyama
- Division of Materials Physics, Graduate School of Engineering Science, Osaka University, Osaka 560-8531, Japan
| | - N Pavlenko
- Center for Electronic Correlations and Magnetism, Experimental Physics VI, Universität Augsburg, D-86135 Augsburg, Germany and Center for Electronic Correlations and Magnetism, Theoretical Physics III, Universität Augsburg, D-86135 Augsburg, Germany and Max Planck Institute for Solid State Research, Heisenbergstraße 1, D-70569 Stuttgart, Germany
| | - T Kopp
- Center for Electronic Correlations and Magnetism, Experimental Physics VI, Universität Augsburg, D-86135 Augsburg, Germany
| | - C Richter
- Center for Electronic Correlations and Magnetism, Experimental Physics VI, Universität Augsburg, D-86135 Augsburg, Germany and Max Planck Institute for Solid State Research, Heisenbergstraße 1, D-70569 Stuttgart, Germany
| | - J Mannhart
- Max Planck Institute for Solid State Research, Heisenbergstraße 1, D-70569 Stuttgart, Germany
| | - S Suga
- Institute of Scientific & Industrial Research, Osaka University, Ibaraki, Osaka 567-0047, Japan
| | - R Claessen
- Physikalisches Institut and Röntgen Center for Complex Materials Systems (RCCM), Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
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13
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Ebad-Allah J, Baldassarre L, Sing M, Claessen R, Brabers VAM, Kuntscher CA. Polaron physics and crossover transition in magnetite probed by pressure-dependent infrared spectroscopy. J Phys Condens Matter 2013; 25:035602. [PMID: 23221151 DOI: 10.1088/0953-8984/25/3/035602] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
The optical properties of magnetite at room temperature were studied by infrared reflectivity measurements as a function of pressure up to 8 GPa. The optical conductivity spectrum consists of a Drude term, two sharp phonon modes, a far-infrared band at around 600 cm(-1) and a pronounced mid-infrared absorption band. With increasing pressure both absorption bands shift to lower frequencies and the phonon modes harden in a linear fashion. Based on the shape of the MIR band, the temperature dependence of the dc transport data, and the occurrence of the far-infrared band in the optical conductivity spectrum, the polaronic coupling strength in magnetite at room temperature should be classified as intermediate. For the lower energy phonon mode an abrupt increase of the linear pressure coefficient occurs at around 6 GPa, which could be attributed to minor alterations of the charge distribution among the different Fe sites.
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Affiliation(s)
- J Ebad-Allah
- Experimentalphysik 2, Universität Augsburg, D-86135 Augsburg, Germany
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14
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van Houselt A, Schäfer J, Zandvliet HJW, Claessen R. Physics in one dimension. J Phys Condens Matter 2013; 25:010301. [PMID: 23355990 DOI: 10.1088/0953-8984/25/1/010301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Affiliation(s)
- A van Houselt
- MESA+ Institute for Nanotechnology, University of Twente, Enschede, The Netherlands.
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15
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Blumenstein C, Meyer S, Mietke S, Schäfer J, Bostwick A, Rotenberg E, Matzdorf R, Claessen R. Au-induced quantum chains on Ge(001)-symmetries, long-range order and the conduction path. J Phys Condens Matter 2013; 25:014015. [PMID: 23220774 DOI: 10.1088/0953-8984/25/1/014015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Atomic nanowires on the Au/Ge(001) surface are investigated for their structural and electronic properties using scanning tunneling microscopy (STM) and angle-resolved photoemission spectroscopy (ARPES). STM reveals two distinct symmetries: a c(8 × 2) describing the basic repeating distances, while the fine structure on top of the wires causes an additional superstructure of p(4 × 1). Both symmetries are long-range ordered as judged from low-energy electron diffraction. The Fermi surface is composed of almost perfectly straight sheets. Thus, the electronic states are one-dimensionally confined. Spatial dI/dV maps, where both topography and density of states (DOS) are probed simultaneously, reveal that the DOS at low energies, i.e. the conduction path, is oriented along the chain direction. This is fully consistent with the recently reported Tomonaga-Luttinger liquid phase of Au/Ge(001), with the density of states being suppressed by a power-law towards the Fermi energy.
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Affiliation(s)
- C Blumenstein
- Physikalisches Institut, Universität Würzburg, Germany
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16
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Glawion S, Haverkort MW, Berner G, Hoinkis M, Gavrila G, Kraus R, Knupfer M, Sing M, Claessen R. Unoccupied electronic structure of TiOCl studied using x-ray absorption near-edge spectroscopy. J Phys Condens Matter 2012; 24:255602. [PMID: 22647754 DOI: 10.1088/0953-8984/24/25/255602] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We study the unoccupied electronic structure of the spin-1/2 quantum magnet TiOCl using x-ray absorption near-edge spectroscopy (XANES) at the Ti L and O K edges. We acquire data both in total electron and fluorescence yield modes (TEY and FY, respectively). While only the latter allows us to access the unconventional low-temperature spin-Peierls (SP) phase of TiOCl, the signal is found to suffer from significant self-absorption in this case. Nevertheless, we conclude from FY data that effects of the SP distortion on the electronic structure are absent in the incommensurate intermediate phase within experimental accuracy. The similarity of room-temperature FY and TEY data, the latter not being obscured by self-absorption, allows us to use TEY spectra for comparison with simulations. These are performed by means of cluster calculations in D(4h) and D(2h) symmetries using two different codes. We extract values of the crystal-field splitting and parameterize our results using the commonly seen notation of Slater, Racah and Butler. In all cases, good agreement with published values from other studies is found.
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Affiliation(s)
- S Glawion
- Experimentelle Physik 4, Universität Würzburg, 97074 Würzburg, Germany
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17
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Höpfner P, Schäfer J, Fleszar A, Dil JH, Slomski B, Meier F, Loho C, Blumenstein C, Patthey L, Hanke W, Claessen R. Three-dimensional spin rotations at the Fermi surface of a strongly spin-orbit coupled surface system. Phys Rev Lett 2012; 108:186801. [PMID: 22681100 DOI: 10.1103/physrevlett.108.186801] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2011] [Indexed: 06/01/2023]
Abstract
The spin texture of the metallic two-dimensional electron system (sqrt[3]×sqrt[3])-Au/Ge(111) is revealed by fully three-dimensional spin-resolved photoemission, as well as by density functional calculations. The large hexagonal Fermi surface, generated by the Au atoms, shows a significant splitting due to spin-orbit interactions. The planar components of the spin exhibit a helical character, accompanied by a strong out-of-plane spin component with alternating signs along the six Fermi surface sections. Moreover, in-plane spin rotations toward a radial direction are observed close to the hexagon corners. Such a threefold-symmetric spin pattern is not described by the conventional Rashba model. Instead, it reveals an interplay with Dresselhaus-like spin-orbit effects as a result of the crystalline anisotropies.
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Affiliation(s)
- P Höpfner
- Physikalisches Institut, Universität Würzburg, 97074 Würzburg, Germany
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18
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Blumenstein C, Schäfer J, Morresi M, Mietke S, Matzdorf R, Claessen R. Symmetry-breaking phase transition without a Peierls instability in conducting monoatomic chains. Phys Rev Lett 2011; 107:165702. [PMID: 22107402 DOI: 10.1103/physrevlett.107.165702] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2011] [Revised: 08/11/2011] [Indexed: 05/31/2023]
Abstract
The one-dimensional (1D) model system Au/Ge(001), consisting of linear chains of single atoms on a surface, is scrutinized for lattice instabilities predicted in the Peierls paradigm. By scanning tunneling microscopy and electron diffraction we reveal a second-order phase transition at 585 K. It leads to charge ordering with transversal and vertical displacements and complex interchain correlations. However, the structural phase transition is not accompanied by the electronic signatures of a charge density wave, thus precluding a Peierls instability as origin. Instead, this symmetry-breaking transition exhibits three-dimensional critical behavior. This reflects a dichotomy between the decoupled 1D electron system and the structural elements that interact via the substrate. Such substrate-mediated coupling between the wires thus appears to have been underestimated also in related chain systems.
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Affiliation(s)
- C Blumenstein
- Physikalisches Institut, Universität Würzburg, Würzburg, Germany
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19
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Glawion S, Heidler J, Haverkort MW, Duda LC, Schmitt T, Strocov VN, Monney C, Zhou KJ, Ruff A, Sing M, Claessen R. Two-spinon and orbital excitations of the spin-Peierls system TiOCl. Phys Rev Lett 2011; 107:107402. [PMID: 21981527 DOI: 10.1103/physrevlett.107.107402] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2010] [Revised: 05/04/2011] [Indexed: 05/31/2023]
Abstract
We combine high-resolution resonant inelastic x-ray scattering with cluster calculations utilizing a recently derived effective magnetic scattering operator to analyze the polarization, excitation energy, and momentum-dependent excitation spectrum of the low-dimensional quantum magnet TiOCl in the range expected for orbital and magnetic excitations (0-2.5 eV). Ti 3d orbital excitations yield complete information on the temperature-dependent crystal-field splitting. In the spin-Peierls phase we observe a dispersive two-spinon excitation and estimate the inter- and intradimer magnetic exchange coupling from a comparison to cluster calculations.
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Affiliation(s)
- S Glawion
- Experimentelle Physik 4, Universität Würzburg, 97074 Würzburg, Germany
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20
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Kusters M, Louwe R, Biemans-vanKastel L, Nieuwenkamp H, Zahradnik R, Claessen R, van Seters R, Huizenga H. 1411 poster CAMERA-BASED INDEPENDENT COUCH HEIGHT VERIFICATION IN RADIATION ONCOLOGY. Radiother Oncol 2011. [DOI: 10.1016/s0167-8140(11)71533-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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21
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Sing M, Glawion S, Schlachter M, Scholz MR, Goss K, Heidler J, Berner G, Claessen R. Photoemission of a doped Mott insulator: spectral weight transfer and a qualitative Mott-Hubbard description. Phys Rev Lett 2011; 106:056403. [PMID: 21405415 DOI: 10.1103/physrevlett.106.056403] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2010] [Indexed: 05/30/2023]
Abstract
The spectral weight evolution of the low-dimensional Mott insulator TiOCl upon alkali-metal dosing has been studied by photoelectron spectroscopy. We observe a spectral weight transfer between the lower Hubbard band and an additional peak upon electron doping, in line with quantitative expectations in the atomic limit for changing the number of singly and doubly occupied sites. This observation is an unconditional hallmark of correlated bands and has not been reported before. In contrast, the absence of a metallic quasiparticle peak can be traced back to a simple one-particle effect.
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Affiliation(s)
- M Sing
- Experimentelle Physik 4, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
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22
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Hofmann A, Cui XY, Schäfer J, Meyer S, Höpfner P, Blumenstein C, Paul M, Patthey L, Rotenberg E, Bünemann J, Gebhard F, Ohm T, Weber W, Claessen R. Renormalization of bulk magnetic electron states at high binding energies. Phys Rev Lett 2009; 102:187204. [PMID: 19518908 DOI: 10.1103/physrevlett.102.187204] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2009] [Indexed: 05/27/2023]
Abstract
The quasiparticle dynamics of electrons in a magnetically ordered state is investigated by high-resolution angle-resolved photoemission of Ni(110) at 10 K. The self-energy is extracted for high binding energies reaching up to 500 meV, using a Gutzwiller calculation as a reference frame for correlated quasiparticles. Significant deviations exist in the 300 meV range, as identified on magnetic bulk bands for the first time. The discrepancy is strikingly well described by a self-energy model assuming interactions with spin excitations. Implications relating to different electron-electron correlation regimes are discussed.
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Affiliation(s)
- A Hofmann
- Physikalisches Institut, Universität Würzburg, 97074 Würzburg, Germany
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23
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Sing M, Berner G, Goss K, Müller A, Ruff A, Wetscherek A, Thiel S, Mannhart J, Pauli SA, Schneider CW, Willmott PR, Gorgoi M, Schäfers F, Claessen R. Profiling the interface electron gas of LaAlO3/SrTiO3 heterostructures with hard x-ray photoelectron spectroscopy. Phys Rev Lett 2009; 102:176805. [PMID: 19518810 DOI: 10.1103/physrevlett.102.176805] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2008] [Indexed: 05/27/2023]
Abstract
The conducting interface of LaAlO3/SrTiO3 heterostructures has been studied by hard x-ray photoelectron spectroscopy. From the Ti 2p signal and its angle dependence we derive that the thickness of the electron gas is much smaller than the probing depth of 4 nm and that the carrier densities vary with increasing number of LaAlO3 overlayers. Our results point to an electronic reconstruction in the LaAlO3 overlayer as the driving mechanism for the conducting interface and corroborate the recent interpretation of the superconducting ground state as being of the Berezinskii-Kosterlitz-Thouless type.
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Affiliation(s)
- M Sing
- Experimentelle Physik 4, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
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24
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Schäfer J, Blumenstein C, Meyer S, Wisniewski M, Claessen R. New model system for a one-dimensional electron liquid: self-organized atomic gold chains on Ge(001). Phys Rev Lett 2008; 101:236802. [PMID: 19113576 DOI: 10.1103/physrevlett.101.236802] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2008] [Indexed: 05/27/2023]
Abstract
Unique electronic properties of self-organized Au atom chains on Ge(001) in novel c(8 x 2) long-range order are revealed by scanning tunneling microscopy. Along the nanowires an exceptionally narrow conduction path exists which is virtually decoupled from the substrate. It is laterally confined to the ultimate limit of single atom dimension, and is strictly separated from its neighbors, as not previously reported. The resulting tunneling conductivity shows a dramatic inhomogeneity of 2 orders of magnitude. The atom chains thus represent an outstandingly close approach to a one-dimensional electron liquid.
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Affiliation(s)
- J Schäfer
- Physikalisches Institut, Universität Würzburg, 97074 Würzburg, Germany
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25
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Stekolnikov AA, Bechstedt F, Wisniewski M, Schäfer J, Claessen R. Atomic nanowires on the Pt/Ge(001) surface: buried Pt-Ge versus top Pt-Pt chains. Phys Rev Lett 2008; 100:196101. [PMID: 18518463 DOI: 10.1103/physrevlett.100.196101] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2007] [Indexed: 05/26/2023]
Abstract
Combining total-energy calculations, electronic-structure studies, and scanning tunneling microscopy (STM), we demonstrate that the observed one-dimensional nanowires are composed of Pt-induced Ge structures instead of Pt chains. Pt-Ge bonds are favored versus Pt-Pt ones. The novel tetramer-dimer-chain model explains STM features and the differential conductivity. The conduction path is related to the chain of alternating Pt-Ge atoms.
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Affiliation(s)
- A A Stekolnikov
- Institut für Festkörpertheorie and -Optik, Friedrich-Schiller-Universität and European Theoretical Spectroscopy Facility (ETSF), Jena, Germany
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26
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Schäfer J, Schrupp D, Rotenberg E, Rossnagel K, Koh H, Blaha P, Claessen R. Electronic quasiparticle renormalization on the spin wave energy scale. Phys Rev Lett 2004; 92:097205. [PMID: 15089509 DOI: 10.1103/physrevlett.92.097205] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/08/2003] [Indexed: 05/24/2023]
Abstract
High-resolution photoemission data of the (110) iron surface reveal the existence of well-defined metallic surface resonances in good correspondence to band calculations. Close to the Fermi level, their dispersion and momentum broadening display anomalies characteristic of quasiparticle renormalization due to coupling to bosonic excitations. Its energy scale exceeds that of phonons by far, and is in striking coincidence with that of the spin wave spectrum in iron. The self-energy behavior thus gives spectroscopic evidence of a quasiparticle mass enhancement due to electron-magnon coupling.
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Affiliation(s)
- J Schäfer
- Institut für Physik, Universität Augsburg, 86135 Augsburg, Germany
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27
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Schäfer J, Sing M, Claessen R, Rotenberg E, Zhou XJ, Thorne RE, Kevan SD. Unusual spectral behavior of charge-density waves with imperfect nesting in a quasi-one-dimensional metal. Phys Rev Lett 2003; 91:066401. [PMID: 12935089 DOI: 10.1103/physrevlett.91.066401] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2002] [Indexed: 05/24/2023]
Abstract
Low-temperature electronic properties of the charge-density-wave system NbSe3 are reported from angle-resolved photoemission at 15 K. The effect of two instabilities q(1) and q(2) on the k-resolved spectral function is observed for the first time. With a pseudogap background, the gap spectra exhibit maxima at Delta*(1) approximately 110 meV and Delta*(2) approximately 45 meV. Imperfectly nested sections of the Fermi surface lack a Fermi-Dirac edge, and show the signature of a dispersion that is modified by self-energy effects. The energy scale is of the order of the effective gap 2 Delta*(2). The effect disappears above T2, suggesting a correlation with the charge-density-wave state.
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Affiliation(s)
- J Schäfer
- Institut für Experimentalphysik, Universität Augsburg, 86135 Augsburg, Germany
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28
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Claessen R, Sing M, Schwingenschlögl U, Blaha P, Dressel M, Jacobsen CS. Spectroscopic signatures of spin-charge separation in the quasi-one-dimensional organic conductor TTF-TCNQ. Phys Rev Lett 2002; 88:096402. [PMID: 11864036 DOI: 10.1103/physrevlett.88.096402] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2001] [Indexed: 05/23/2023]
Abstract
The electronic structure of the quasi-one-dimensional organic conductor TTF-TCNQ is studied by angle-resolved photoelectron spectroscopy (ARPES). The experimental spectra reveal significant discrepancies to band theory. We demonstrate that the measured dispersions can be consistently mapped onto the one-dimensional Hubbard model at finite doping. This interpretation is further supported by a remarkable transfer of spectral weight as a function of temperature. The ARPES data thus show spectroscopic signatures of spin-charge separation on an energy scale of the conduction bandwidth.
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Affiliation(s)
- R Claessen
- Experimentalphysik II, Universität Augsburg, D-86135 Augsburg, Germany
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29
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Schäfer J, Rotenberg E, Kevan SD, Blaha P, Claessen R, Thorne RE. High-temperature symmetry breaking in the electronic band structure of the quasi-one-dimensional solid NbSe3. Phys Rev Lett 2001; 87:196403. [PMID: 11690438 DOI: 10.1103/physrevlett.87.196403] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2001] [Indexed: 05/23/2023]
Abstract
The electronic band structure of the Peierls compound NbSe3 has been explored for its symmetries with microspot synchrotron photoemission. The Fermi level crossings and deviations from one-dimensional behavior are identified. Density-functional calculations of the Fermi surfaces confirm the nesting conditions relevant for the two phase transitions. The instability along the chains with superstructure periodicity q = 0.44 A(-1) induces a backfolding of the electronic bands, and the Fermi level crossings appear suppressed. This broken symmetry is observed in the fluctuation regime at more than twice the critical temperature, where the correlation length is strongly reduced.
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Affiliation(s)
- J Schäfer
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
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30
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Claessen R, Anderson RO, Gweon G, Allen JW, Ellis WP, Janowitz C, Olson CG, Shen ZX, Eyert V, Skibowski M, Friemelt K, Bucher E, Hüfner S. Complete band-structure determination of the quasi-two-dimensional Fermi-liquid reference compound TiTe2. Phys Rev B Condens Matter 1996; 54:2453-2465. [PMID: 9986092 DOI: 10.1103/physrevb.54.2453] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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31
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Straub T, Fauth K, Finteis T, Hengsberger M, Claessen R, Steiner P, Hüfner S, Blaha P. Valence-band maximum in the layered semiconductor WSe2: Application of constant-energy contour mapping by photoemission. Phys Rev B Condens Matter 1996; 53:R16152-R16155. [PMID: 9983520 DOI: 10.1103/physrevb.53.r16152] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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32
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Reinert F, Kumar S, Steiner P, Claessen R, H�fner S. The electronic structure of KMnO4 investigated by photoemission and electron-energy-loss spectroscopy. ACTA ACUST UNITED AC 1994. [DOI: 10.1007/bf01317405] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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33
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Anderson RO, Claessen R, Allen JW, Olson CG, Janowitz C, Liu LZ, Park J, Maple MB, Dalichaouch Y, Jardim RF, Early EA, Oh S, Ellis WP. Luttinger Fermi surface of metallic gap spectral weight in Nd1.85Ce0.15CuO4-y. Phys Rev Lett 1993; 70:3163-3166. [PMID: 10053791 DOI: 10.1103/physrevlett.70.3163] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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34
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Claessen R, Smith MG, Goodenough JB, Allen JW. Electronic structure of BaSn1-xSbxO3 studied by photoemission spectroscopy. Phys Rev B Condens Matter 1993; 47:1788-1793. [PMID: 10006214 DOI: 10.1103/physrevb.47.1788] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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35
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Claessen R, Anderson RO, Allen JW, Olson CG, Janowitz C, Ellis WP, Harm S, Kalning M, Manzke R, Skibowski M. Fermi-liquid line shapes measured by angle-resolved photoemission spectroscopy on 1-T-TiTe2. Phys Rev Lett 1992; 69:808-811. [PMID: 10047038 DOI: 10.1103/physrevlett.69.808] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
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36
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Mante G, Claessen R, Huss A, Manzke R, Skibowski M, Wolf T, Knupfer M, Fink J. Occupied electronic structure and Fermi surface of YBa2Cu3O6.8. Phys Rev B Condens Matter 1991; 44:9500-9507. [PMID: 9998933 DOI: 10.1103/physrevb.44.9500] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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37
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Claessen R, Mante G, Huss A, Manzke R, Skibowski M, Wolf T, Fink J. Evidence for a surface-derived electronic state on YBa2Cu3O6.8. Phys Rev B Condens Matter 1991; 44:2399-2402. [PMID: 9999803 DOI: 10.1103/physrevb.44.2399] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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38
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Fink J, Nücker N, Romberg H, Alexander M, Adelmann P, Mante J, Claessen R, Buslaps T, Harm S, Manzke R, Skibowsky M. Investigations of the electronic structure of cuprate superconductors by high-energy spectroscopy. ACTA ACUST UNITED AC 1990. [DOI: 10.1016/0022-5088(90)90508-h] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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Mante G, Claessen R, Buslaps T, Harm S, Manzke R, Skibowski M, Fink J. Electronic structure and Fermi surface of Bi2Sr2CaCu2O8. ACTA ACUST UNITED AC 1990. [DOI: 10.1007/bf01357500] [Citation(s) in RCA: 78] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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40
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Carstensen H, Claessen R, Manzke R, Skibowski M. Direct determination of III-V semiconductor surface band gaps. Phys Rev B Condens Matter 1990; 41:9880-9885. [PMID: 9993369 DOI: 10.1103/physrevb.41.9880] [Citation(s) in RCA: 48] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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41
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Claessen R, Burandt B, Carstensen H, Skibowski M. Conduction-band structure and charge-density waves in 1T-TaS2. Phys Rev B Condens Matter 1990; 41:8270-8277. [PMID: 9993148 DOI: 10.1103/physrevb.41.8270] [Citation(s) in RCA: 29] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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42
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Claessen R, Manzke R, Carstensen H, Burandt B, Buslaps T, Skibowski M, Fink J. Surface study of the 83-K superconductor Bi2Sr2CaCu2O8 by low-energy electron diffraction and angle-resolved inverse photoemission spectroscopy. Phys Rev B Condens Matter 1989; 39:7316-7319. [PMID: 9947398 DOI: 10.1103/physrevb.39.7316] [Citation(s) in RCA: 43] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/12/2023]
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43
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Claessen R, Carstensen H, Skibowski M. Conduction-band structure of graphite single crystals studied by angle-resolved inverse photoemission and target-current spectroscopy. Phys Rev B Condens Matter 1988; 38:12582-12588. [PMID: 9946203 DOI: 10.1103/physrevb.38.12582] [Citation(s) in RCA: 22] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/11/2023]
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