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Sánchez-Barriga J, Clark OJ, Vergniory MG, Krivenkov M, Varykhalov A, Rader O, Schoop LM. Experimental Realization of a Three-Dimensional Dirac Semimetal Phase with a Tunable Lifshitz Transition in Au_{2}Pb. Phys Rev Lett 2023; 130:236402. [PMID: 37354399 DOI: 10.1103/physrevlett.130.236402] [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: 06/09/2022] [Revised: 03/02/2023] [Accepted: 04/28/2023] [Indexed: 06/26/2023]
Abstract
Three-dimensional Dirac semimetals are an exotic state of matter that continue to attract increasing attention due to the unique properties of their low-energy excitations. Here, by performing angle-resolved photoemission spectroscopy, we investigate the electronic structure of Au_{2}Pb across a wide temperature range. Our experimental studies on the (111)-cleaved surface unambiguously demonstrate that Au_{2}Pb is a three-dimensional Dirac semimetal characterized by the presence of a bulk Dirac cone projected off-center of the bulk Brillouin zone (BZ), in agreement with our theoretical calculations. Unusually, we observe that the bulk Dirac cone is significantly shifted by more than 0.4 eV to higher binding energies with reducing temperature, eventually going through a Lifshitz transition. The pronounced downward shift is qualitatively reproduced by our calculations indicating that an enhanced orbital overlap upon compression of the lattice, which preserves C_{4} rotational symmetry, is the main driving mechanism for the Lifshitz transition. These findings not only broaden the range of currently known materials exhibiting three-dimensional Dirac phases, but also show a viable mechanism by which it could be possible to switch on and off the contribution of the degeneracy point to electron transport without external doping.
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Affiliation(s)
- J Sánchez-Barriga
- Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Strasse 15, 12489 Berlin, Germany
- IMDEA Nanoscience, C/ Faraday 9, Campus de Cantoblanco, 28049 Madrid, Spain
| | - O J Clark
- Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Strasse 15, 12489 Berlin, Germany
| | - M G Vergniory
- Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Strasse 15, 12489 Berlin, Germany
- IMDEA Nanoscience, C/ Faraday 9, Campus de Cantoblanco, 28049 Madrid, Spain
- Donostia International Physics Center, 20018 Donostia-San Sebastián, Spain
- Max Planck Institute for Chemical Physics of Solids, Dresden D-01187, Germany
- Department of Chemistry, Princeton University, Princeton, 08544 New Jersey, USA
| | - M Krivenkov
- Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Strasse 15, 12489 Berlin, Germany
| | - A Varykhalov
- Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Strasse 15, 12489 Berlin, Germany
| | - O Rader
- Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Strasse 15, 12489 Berlin, Germany
| | - L M Schoop
- Department of Chemistry, Princeton University, Princeton, 08544 New Jersey, USA
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2
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Krivenkov M, Marchenko D, Sajedi M, Fedorov A, Clark OJ, Sánchez-Barriga J, Rienks EDL, Rader O, Varykhalov A. On the problem of Dirac cones in fullerenes on gold. Nanoscale 2022; 14:9124-9133. [PMID: 35723255 DOI: 10.1039/d1nr07981f] [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] [Indexed: 06/15/2023]
Abstract
Artificial graphene based on molecular networks enables the creation of novel 2D materials with unique electronic and topological properties. Landau quantization has been demonstrated by CO molecules arranged on the two-dimensional electron gas on Cu(111) and the observation of electron quantization may succeed based on the created gauge fields. Recently, it was reported that instead of individual manipulation of CO molecules, simple deposition of nonpolar C60 molecules on Cu(111) and Au(111) produces artificial graphene as evidenced by Dirac cones in photoemission spectroscopy. Here, we show that C60-induced Dirac cones on Au(111) have a different origin. We argue that those are related to umklapp diffraction of surface electronic bands of Au on the molecular grid of C60 in the final state of photoemission. We test this alternative explanation by precisely probing the dimensionality of the observed conical features in the photoemission spectra, by varying both the incident photon energy and the degree of charge doping via alkali adatoms. Using density functional theory calculations and spin-resolved photoemission we reveal the origin of the replicating Au(111) bands and resolve them as deep leaky surface resonances derived from the bulk Au sp-band residing at the boundary of its surface projection. We also discuss the manifold nature of these resonances which gives rise to an onion-like Fermi surface of Au(111).
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Affiliation(s)
- M Krivenkov
- Helmholtz-Zentrum Berlin für Materialien und Energie, BESSY II, Albert-Einstein-Str. 15, 12489 Berlin, Germany.
| | - D Marchenko
- Helmholtz-Zentrum Berlin für Materialien und Energie, BESSY II, Albert-Einstein-Str. 15, 12489 Berlin, Germany.
| | - M Sajedi
- Helmholtz-Zentrum Berlin für Materialien und Energie, BESSY II, Albert-Einstein-Str. 15, 12489 Berlin, Germany.
| | - A Fedorov
- Helmholtz-Zentrum Berlin für Materialien und Energie, BESSY II, Albert-Einstein-Str. 15, 12489 Berlin, Germany.
- IFW Dresden, Helmholtzstr. 20, 01069 Dresden, Germany
- Joint Laboratory 'Functional Quantum Materials' at BESSY II, 12489, Berlin, Germany
| | - O J Clark
- Helmholtz-Zentrum Berlin für Materialien und Energie, BESSY II, Albert-Einstein-Str. 15, 12489 Berlin, Germany.
| | - J Sánchez-Barriga
- Helmholtz-Zentrum Berlin für Materialien und Energie, BESSY II, Albert-Einstein-Str. 15, 12489 Berlin, Germany.
| | - E D L Rienks
- Helmholtz-Zentrum Berlin für Materialien und Energie, BESSY II, Albert-Einstein-Str. 15, 12489 Berlin, Germany.
| | - O Rader
- Helmholtz-Zentrum Berlin für Materialien und Energie, BESSY II, Albert-Einstein-Str. 15, 12489 Berlin, Germany.
| | - A Varykhalov
- Helmholtz-Zentrum Berlin für Materialien und Energie, BESSY II, Albert-Einstein-Str. 15, 12489 Berlin, Germany.
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Rienks EDL, Wimmer S, Sánchez-Barriga J, Caha O, Mandal PS, Růžička J, Ney A, Steiner H, Volobuev VV, Groiss H, Albu M, Kothleitner G, Michalička J, Khan SA, Minár J, Ebert H, Bauer G, Freyse F, Varykhalov A, Rader O, Springholz G. Large magnetic gap at the Dirac point in Bi2Te3/MnBi2Te4 heterostructures. Nature 2019; 576:423-428. [DOI: 10.1038/s41586-019-1826-7] [Citation(s) in RCA: 125] [Impact Index Per Article: 25.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Accepted: 10/18/2019] [Indexed: 11/09/2022]
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4
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Marchenko D, Evtushinsky DV, Golias E, Varykhalov A, Seyller T, Rader O. Extremely flat band in bilayer graphene. Sci Adv 2018; 4:eaau0059. [PMID: 30430134 PMCID: PMC6226281 DOI: 10.1126/sciadv.aau0059] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2018] [Accepted: 10/04/2018] [Indexed: 05/06/2023]
Abstract
We propose a novel mechanism of flat band formation based on the relative biasing of only one sublattice against other sublattices in a honeycomb lattice bilayer. The mechanism allows modification of the band dispersion from parabolic to "Mexican hat"-like through the formation of a flattened band. The mechanism is well applicable for bilayer graphene-both doped and undoped. By angle-resolved photoemission from bilayer graphene on SiC, we demonstrate the possibility of realizing this extremely flattened band (< 2-meV dispersion), which extends two-dimensionally in a k-space area around the K ¯ point and results in a disk-like constant energy cut. We argue that our two-dimensional flat band model and the experimental results have the potential to contribute to achieving superconductivity of graphene- or graphite-based systems at elevated temperatures.
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Affiliation(s)
- D. Marchenko
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489 Berlin, Germany
- Corresponding author.
| | - D. V. Evtushinsky
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - E. Golias
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - A. Varykhalov
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - Th. Seyller
- Institut für Physik, Technische Universität Chemnitz, Reichenhainer Str. 70, 09126 Chemnitz, Germany
| | - O. Rader
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489 Berlin, Germany
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5
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Kuroda K, Tomita T, Suzuki MT, Bareille C, Nugroho AA, Goswami P, Ochi M, Ikhlas M, Nakayama M, Akebi S, Noguchi R, Ishii R, Inami N, Ono K, Kumigashira H, Varykhalov A, Muro T, Koretsune T, Arita R, Shin S, Kondo T, Nakatsuji S. Evidence for magnetic Weyl fermions in a correlated metal. Nat Mater 2017; 16:1090-1095. [PMID: 28967918 DOI: 10.1038/nmat4987] [Citation(s) in RCA: 115] [Impact Index Per Article: 16.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2017] [Accepted: 08/21/2017] [Indexed: 06/07/2023]
Abstract
Weyl fermions have been observed as three-dimensional, gapless topological excitations in weakly correlated, inversion-symmetry-breaking semimetals. However, their realization in spontaneously time-reversal-symmetry-breaking phases of strongly correlated materials has so far remained hypothetical. Here, we report experimental evidence for magnetic Weyl fermions in Mn3Sn, a non-collinear antiferromagnet that exhibits a large anomalous Hall effect, even at room temperature. Detailed comparison between angle-resolved photoemission spectroscopy (ARPES) measurements and density functional theory (DFT) calculations reveals significant bandwidth renormalization and damping effects due to the strong correlation among Mn 3d electrons. Magnetotransport measurements provide strong evidence for the chiral anomaly of Weyl fermions-namely, the emergence of positive magnetoconductance only in the presence of parallel electric and magnetic fields. Since weak magnetic fields (approximately 10 mT) are adequate to control the distribution of Weyl points and the large fictitious fields (equivalent to approximately a few hundred T) produced by them in momentum space, our discovery lays the foundation for a new field of science and technology involving the magnetic Weyl excitations of strongly correlated electron systems such as Mn3Sn.
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Affiliation(s)
- K Kuroda
- Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan
| | - T Tomita
- Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan
- CREST, Japan Science and Technology Agency (JST), 4-1-8 Honcho Kawaguchi, Saitama 332-0012, Japan
| | - M-T Suzuki
- CREST, Japan Science and Technology Agency (JST), 4-1-8 Honcho Kawaguchi, Saitama 332-0012, Japan
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - C Bareille
- Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan
| | - A A Nugroho
- Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan
- Faculty of Mathematics and Natural Sciences, Institut Teknologi Bandung, Jl. Ganesha 10, 40132 Bandung, Indonesia
| | - P Goswami
- Condensed Matter Theory Center and Joint Quantum Institute, Department of Physics, University of Maryland, College Park, Maryland 20742- 4111, USA
- Department of Physics and Astronomy, 2145 Sheridan Road, Evanston, Illinois 60208, USA
| | - M Ochi
- Department of Physics, Osaka University, Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan
| | - M Ikhlas
- Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan
- CREST, Japan Science and Technology Agency (JST), 4-1-8 Honcho Kawaguchi, Saitama 332-0012, Japan
| | - M Nakayama
- Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan
| | - S Akebi
- Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan
| | - R Noguchi
- Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan
| | - R Ishii
- Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan
| | - N Inami
- Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801, Japan
| | - K Ono
- Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801, Japan
| | - H Kumigashira
- Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Tsukuba, Ibaraki 305-0801, Japan
| | - A Varykhalov
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Strasse 15, 12489 Berlin, Germany
| | - T Muro
- Japan Synchrotron Radiation Research Institute (JASRI), 1-1-1 Kouto, Sayo, Hyogo 679-5198, Japan
| | - T Koretsune
- CREST, Japan Science and Technology Agency (JST), 4-1-8 Honcho Kawaguchi, Saitama 332-0012, Japan
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - R Arita
- CREST, Japan Science and Technology Agency (JST), 4-1-8 Honcho Kawaguchi, Saitama 332-0012, Japan
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - S Shin
- Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan
| | - Takeshi Kondo
- Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan
| | - S Nakatsuji
- Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan
- CREST, Japan Science and Technology Agency (JST), 4-1-8 Honcho Kawaguchi, Saitama 332-0012, Japan
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6
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Wang Z, McKeown Walker S, Tamai A, Wang Y, Ristic Z, Bruno FY, de la Torre A, Riccò S, Plumb NC, Shi M, Hlawenka P, Sánchez-Barriga J, Varykhalov A, Kim TK, Hoesch M, King PDC, Meevasana W, Diebold U, Mesot J, Moritz B, Devereaux TP, Radovic M, Baumberger F. Tailoring the nature and strength of electron-phonon interactions in the SrTiO3(001) 2D electron liquid. Nat Mater 2016; 15:835-839. [PMID: 27064529 DOI: 10.1038/nmat4623] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2015] [Accepted: 03/10/2016] [Indexed: 06/05/2023]
Abstract
Surfaces and interfaces offer new possibilities for tailoring the many-body interactions that dominate the electrical and thermal properties of transition metal oxides. Here, we use the prototypical two-dimensional electron liquid (2DEL) at the SrTiO3(001) surface to reveal a remarkably complex evolution of electron-phonon coupling with the tunable carrier density of this system. At low density, where superconductivity is found in the analogous 2DEL at the LaAlO3/SrTiO3 interface, our angle-resolved photoemission data show replica bands separated by 100 meV from the main bands. This is a hallmark of a coherent polaronic liquid and implies long-range coupling to a single longitudinal optical phonon branch. In the overdoped regime the preferential coupling to this branch decreases and the 2DEL undergoes a crossover to a more conventional metallic state with weaker short-range electron-phonon interaction. These results place constraints on the theoretical description of superconductivity and allow a unified understanding of the transport properties in SrTiO3-based 2DELs.
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Affiliation(s)
- Z Wang
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland
| | - S McKeown Walker
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland
| | - A Tamai
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland
| | - Y Wang
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Department of Applied Physics, Stanford University, Stanford, California 94305, USA
| | - Z Ristic
- Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - F Y Bruno
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland
| | - A de la Torre
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland
| | - S Riccò
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland
| | - N C Plumb
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - M Shi
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - P Hlawenka
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY-II, 12489 Berlin, Germany
| | - J Sánchez-Barriga
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY-II, 12489 Berlin, Germany
| | - A Varykhalov
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY-II, 12489 Berlin, Germany
| | - T K Kim
- Diamond Light Source, Harwell Campus, Didcot OX11 0DE, UK
| | - M Hoesch
- Diamond Light Source, Harwell Campus, Didcot OX11 0DE, UK
| | - P D C King
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, Fife KY16 9SS, UK
| | - W Meevasana
- School of Physics and NANOTEC-SUT Center of Excellence on Advanced Functional Nanomaterials, Suranaree University of Technology, Nakhon Ratchasima 30000, Thailand
| | - U Diebold
- Institute of Applied Physics, Vienna University of Technology, Wiedner Hauptstrasse 8-10/134, A-1040 Vienna, Austria
| | - J Mesot
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
- Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
- Laboratory for Solid State Physics, ETH Zürich, CH-8093 Zürich, Switzerland
| | - B Moritz
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - T P Devereaux
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
- Geballe Laboratory for Advanced Materials, Stanford University, Stanford, California 94305, USA
| | - M Radovic
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
- SwissFEL, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
| | - F Baumberger
- Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland
- Department of Quantum Matter Physics, University of Geneva, 24 Quai Ernest-Ansermet, 1211 Geneva 4, Switzerland
- SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews, Fife KY16 9SS, UK
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Sánchez-Barriga J, Varykhalov A, Springholz G, Steiner H, Kirchschlager R, Bauer G, Caha O, Schierle E, Weschke E, Ünal AA, Valencia S, Dunst M, Braun J, Ebert H, Minár J, Golias E, Yashina LV, Ney A, Holý V, Rader O. Nonmagnetic band gap at the Dirac point of the magnetic topological insulator (Bi(1-x)Mn(x))2Se3. Nat Commun 2016; 7:10559. [PMID: 26892831 PMCID: PMC4762886 DOI: 10.1038/ncomms10559] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [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: 06/13/2015] [Accepted: 12/26/2015] [Indexed: 12/04/2022] Open
Abstract
Magnetic doping is expected to open a band gap at the Dirac point of topological insulators by breaking time-reversal symmetry and to enable novel topological phases. Epitaxial (Bi1−xMnx)2Se3 is a prototypical magnetic topological insulator with a pronounced surface band gap of ∼100 meV. We show that this gap is neither due to ferromagnetic order in the bulk or at the surface nor to the local magnetic moment of the Mn, making the system unsuitable for realizing the novel phases. We further show that Mn doping does not affect the inverted bulk band gap and the system remains topologically nontrivial. We suggest that strong resonant scattering processes cause the gap at the Dirac point and support this by the observation of in-gap states using resonant photoemission. Our findings establish a mechanism for gap opening in topological surface states which challenges the currently known conditions for topological protection. Doping a topological insulator with magnetic impurities is expected to induce ferromagnetism and open a band gap in its surface states. Here, the authors study Mn-doped Bi2Se3, finding a mechanism for band gap opening in topologically-protected surface states which is not of magnetic origin.
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Affiliation(s)
- J Sánchez-Barriga
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - A Varykhalov
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - G Springholz
- Institut für Halbleiter und Festkörperphysik, Johannes Kepler Universität, Altenbergerstr. 69, 4040 Linz, Austria
| | - H Steiner
- Institut für Halbleiter und Festkörperphysik, Johannes Kepler Universität, Altenbergerstr. 69, 4040 Linz, Austria
| | - R Kirchschlager
- Institut für Halbleiter und Festkörperphysik, Johannes Kepler Universität, Altenbergerstr. 69, 4040 Linz, Austria
| | - G Bauer
- Institut für Halbleiter und Festkörperphysik, Johannes Kepler Universität, Altenbergerstr. 69, 4040 Linz, Austria
| | - O Caha
- Department of Condensed Matter Physics, CEITEC, Masaryk University, Kotlarska 2, 61137 Brno, Czech Republic
| | - E Schierle
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - E Weschke
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - A A Ünal
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - S Valencia
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - M Dunst
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, 81377 München, Germany
| | - J Braun
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, 81377 München, Germany
| | - H Ebert
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, 81377 München, Germany
| | - J Minár
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstr. 5-13, 81377 München, Germany.,New Technologies Research Centre, University of West Bohemia, Univerzitni 8, 306 14 Pilsen, Czech Republic
| | - E Golias
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - L V Yashina
- Department of Chemistry, Moscow State University, Leninskie Gory 1/3, 119991 Moscow, Russia
| | - A Ney
- Institut für Halbleiter und Festkörperphysik, Johannes Kepler Universität, Altenbergerstr. 69, 4040 Linz, Austria
| | - V Holý
- Department of Condensed Matter Physics, Charles University, Ke Karlovu 5, 12116 Prague, Czech Republic
| | - O Rader
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489 Berlin, Germany
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8
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Abstract
Spin and pseudospin in graphene are known to interact under enhanced spin–orbit interaction giving rise to an in-plane Rashba spin texture. Here we show that Au-intercalated graphene on Fe(110) displays a large (∼230 meV) bandgap with out-of-plane hedgehog-type spin reorientation around the gapped Dirac point. We identify two causes responsible. First, a giant Rashba effect (∼70 meV splitting) away from the Dirac point and, second, the breaking of the six-fold graphene symmetry at the interface. This is demonstrated by a strong one-dimensional anisotropy of the graphene dispersion imposed by the two-fold-symmetric (110) substrate. Surprisingly, the graphene Fermi level is systematically tuned by the Au concentration and can be moved into the bandgap. We conclude that the out-of-plane spin texture is not only of fundamental interest but can be tuned at the Fermi level as a model for electrical gating of spin in a spintronic device. Potential electronic applications of graphene rely on controlling its spin-dependent properties. Here, the authors use spin-resolved photoemission spectroscopy to demonstrate how Au-intercalation produces gapped one-dimensional quasi-freestanding graphene on Fe(110) with tunable Fermi surface spin texture.
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Affiliation(s)
- A Varykhalov
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - J Sánchez-Barriga
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - D Marchenko
- 1] Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489 Berlin, Germany [2] Physikalische und Theoretische Chemie, Freie Universität Berlin, Takustraße 3, 14195 Berlin, Germany
| | - P Hlawenka
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - P S Mandal
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489 Berlin, Germany
| | - O Rader
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Straße 15, 12489 Berlin, Germany
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9
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Rybkina AA, Rybkin AG, Adamchuk VK, Marchenko D, Varykhalov A, Sánchez-Barriga J, Shikin AM. The graphene/Au/Ni interface and its application in the construction of a graphene spin filter. Nanotechnology 2013; 24:295201. [PMID: 23799659 DOI: 10.1088/0957-4484/24/29/295201] [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] [Indexed: 06/02/2023]
Abstract
A modification of the contact of graphene with ferromagnetic electrodes in a model of the graphene spin filter allowing restoration of the graphene electronic structure is proposed. It is suggested for this aim to intercalate into the interface between the graphene and the ferromagnetic (Ni or Co) electrode a Au monolayer to block the strong interaction between the graphene and Ni (Co) and, thus, prevent destruction of the graphene electronic structure which evolves in direct contact of graphene with Ni (Co). It is also suggested to insert an additional buffer graphene monolayer with the size limited by that of the electrode between the main graphene sheet providing spin current transport and the Au/Ni electrode injecting the spin current. This will prevent the spin transport properties of graphene from influencing contact phenomena and eliminate pinning of the graphene electronic structure relative to the Fermi level of the metal, thus ensuring efficient outflow of injected electrons into the graphene. The role of the spin structure of the graphene/Au/Ni interface with enhanced spin-orbit splitting of graphene π states is also discussed, and its use is proposed for additional spin selection in the process of the electron excitation.
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Affiliation(s)
- A A Rybkina
- St.-Petersburg State University, Ulyanovskaya 1, Petrodvoretz, St.-Petersburg 198504, Russia
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10
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Scholz MR, Sánchez-Barriga J, Braun J, Marchenko D, Varykhalov A, Lindroos M, Wang YJ, Lin H, Bansil A, Minár J, Ebert H, Volykhov A, Yashina LV, Rader O. Reversal of the circular dichroism in angle-resolved photoemission from Bi2Te3. Phys Rev Lett 2013; 110:216801. [PMID: 23745908 DOI: 10.1103/physrevlett.110.216801] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/04/2012] [Revised: 03/09/2013] [Indexed: 06/02/2023]
Abstract
The helical Dirac fermions at the surface of topological insulators show a strong circular dichroism which has been explained as being due to either the initial-state spin angular momentum, the initial-state orbital angular momentum, or the handedness of the experimental setup. All of these interpretations conflict with our data from Bi(2)Te(3) which depend on the photon energy and show several sign changes. Our one-step photoemission calculations coupled to ab initio theory confirm the sign change and assign the dichroism to a final-state effect. Instead, the spin polarization of the photoelectrons excited with linearly polarized light remains a reliable probe for the spin in the initial state.
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Affiliation(s)
- M R Scholz
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Strasse 15, 12489 Berlin, Germany
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11
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Scholz MR, Sánchez-Barriga J, Marchenko D, Varykhalov A, Volykhov A, Yashina LV, Rader O. Tolerance of topological surface states towards magnetic moments: Fe on Bi2Se3. Phys Rev Lett 2012; 108:256810. [PMID: 23004639 DOI: 10.1103/physrevlett.108.256810] [Citation(s) in RCA: 16] [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: 12/10/2011] [Indexed: 06/01/2023]
Abstract
We study the effect of Fe impurities deposited on the surface of the topological insulator Bi(2)Se(3) by means of core-level and angle-resolved photoelectron spectroscopy. The topological surface state reveals surface electron doping when the Fe is deposited at room temperature and hole doping with increased linearity when deposited at low temperature (~8 K). We show that in both cases the surface state remains intact and gapless, in contradiction to current belief. Our results suggest that the surface state can very well exist at functional interfaces with ferromagnets in future devices.
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Affiliation(s)
- M R Scholz
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Strasse 15, D-12489 Berlin, Germany
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12
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Varykhalov A, Marchenko D, Scholz MR, Rienks EDL, Kim TK, Bihlmayer G, Sánchez-Barriga J, Rader O. Ir(111) surface state with giant Rashba splitting persists under graphene in air. Phys Rev Lett 2012; 108:066804. [PMID: 22401103 DOI: 10.1103/physrevlett.108.066804] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2011] [Indexed: 05/31/2023]
Abstract
We reveal a giant Rashba effect (α(R)≈1.3 eV Å) on a surface state of Ir(111) by angle-resolved photoemission and by density functional theory. It is demonstrated that the existence of the surface state, its spin polarization, and the size of its Rashba-type spin-orbit splitting remain unaffected when Ir is covered with graphene. The graphene protection is, in turn, sufficient for the spin-split surface state to survive in ambient atmosphere. We discuss this result along with indications for a topological protection of the surface state.
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Affiliation(s)
- A Varykhalov
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Berlin, Germany
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13
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Carbone C, Veronese M, Moras P, Gardonio S, Grazioli C, Zhou PH, Rader O, Varykhalov A, Krull C, Balashov T, Mugarza A, Gambardella P, Lebègue S, Eriksson O, Katsnelson MI, Lichtenstein AI. Correlated electrons step by step: itinerant-to-localized transition of fe impurities in free-electron metal hosts. Phys Rev Lett 2010; 104:117601. [PMID: 20366500 DOI: 10.1103/physrevlett.104.117601] [Citation(s) in RCA: 3] [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: 06/05/2009] [Indexed: 05/29/2023]
Abstract
High-resolution photoemission spectroscopy and ab initio calculations have been employed to analyze the onset and progression of d-sp hybridization in Fe impurities deposited on alkali metal films. The interplay between delocalization, mediated by the free-electron environment, and Coulomb interaction among d electrons gives rise to complex electronic configurations. The multiplet structure of a single Fe atom evolves and gradually dissolves into a quasiparticle peak near the Fermi level with increasing host electron density. The effective multiorbital impurity problem within the exact diagonalization scheme describes the whole range of hybridizations.
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Affiliation(s)
- C Carbone
- Istituto di Struttura della Materia, Consiglio Nazionale delle Ricerche, I-34012 Trieste, Italy
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14
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Sánchez-Barriga J, Fink J, Boni V, Di Marco I, Braun J, Minár J, Varykhalov A, Rader O, Bellini V, Manghi F, Ebert H, Katsnelson MI, Lichtenstein AI, Eriksson O, Eberhardt W, Dürr HA. Strength of correlation effects in the electronic structure of iron. Phys Rev Lett 2009; 103:267203. [PMID: 20366340 DOI: 10.1103/physrevlett.103.267203] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2009] [Indexed: 05/29/2023]
Abstract
The strength of electronic correlation effects in the spin-dependent electronic structure of ferromagnetic bcc Fe(110) has been investigated by means of spin and angle-resolved photoemission spectroscopy. The experimental results are compared to theoretical calculations within the three-body scattering approximation and within the dynamical mean-field theory, together with one-step model calculations of the photoemission process. This comparison indicates that the present state of the art many-body calculations, although improving the description of correlation effects in Fe, give too small mass renormalizations and scattering rates thus demanding more refined many-body theories including nonlocal fluctuations.
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Affiliation(s)
- J Sánchez-Barriga
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Strasse 15, D-12489 Berlin, Germany
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15
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Borisenko SV, Kordyuk AA, Zabolotnyy VB, Inosov DS, Evtushinsky D, Büchner B, Yaresko AN, Varykhalov A, Follath R, Eberhardt W, Patthey L, Berger H. Two energy gaps and Fermi-surface "arcs" in NbSe2. Phys Rev Lett 2009; 102:166402. [PMID: 19518731 DOI: 10.1103/physrevlett.102.166402] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2008] [Indexed: 05/27/2023]
Abstract
Using angle-resolved photoemission spectroscopy, we report on the direct observation of the energy gap in 2H-NbSe2 caused by the charge-density waves (CDW). The gap opens in the regions of the momentum space connected by the CDW vectors, which implies a nesting mechanism of CDW formation. In remarkable analogy with the pseudogap in cuprates, the detected energy gap also exists in the normal state (T>T0) where it breaks the Fermi surface into "arcs," it is nonmonotonic as a function of temperature with a local minimum at the CDW transition temperature (T0), and it forestalls the superconducting gap by excluding the nested portions of the Fermi surface from participating in superconductivity.
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Affiliation(s)
- S V Borisenko
- Leibniz-Institute for Solid State Research, IFW-Dresden, D-01171, Dresden, Germany
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16
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Koitzsch A, Inosov DS, Evtushinsky DV, Zabolotnyy VB, Kordyuk AA, Kondrat A, Hess C, Knupfer M, Büchner B, Sun GL, Hinkov V, Lin CT, Varykhalov A, Borisenko SV. Temperature and doping-dependent renormalization effects of the low energy electronic structure of Ba1-xKxFe2As2 single crystals. Phys Rev Lett 2009; 102:167001. [PMID: 19518744 DOI: 10.1103/physrevlett.102.167001] [Citation(s) in RCA: 3] [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: 11/03/2008] [Revised: 01/30/2009] [Indexed: 05/27/2023]
Abstract
We investigate the low energy electronic structure of Ba1-xKxFe2As2 (x=0; 0.3, T_{c}=32 K) single crystals by angle-resolved photoemission spectroscopy with a focus on the renormalization of the dispersion. A kink feature is detected at E approximately 25 meV for the doped compound which vanishes at T=200 K but stays virtually constant when T_{c} is crossed. Our experimental findings rule out the magnetic resonance mode as the origin of the kink and render conventional electron-phonon coupling unlikely. They put stringent restrictions on the dominant source of the electronic interaction channel.
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Affiliation(s)
- A Koitzsch
- Institute for Solid State Research, IFW-Dresden, P.O.Box 270116, D-01171 Dresden, Germany
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17
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Zabolotnyy VB, Inosov DS, Evtushinsky DV, Koitzsch A, Kordyuk AA, Sun GL, Park JT, Haug D, Hinkov V, Boris AV, Lin CT, Knupfer M, Yaresko AN, Büchner B, Varykhalov A, Follath R, Borisenko SV. (pi, pi) electronic order in iron arsenide superconductors. Nature 2009; 457:569-72. [PMID: 19177126 DOI: 10.1038/nature07714] [Citation(s) in RCA: 177] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2008] [Accepted: 12/02/2008] [Indexed: 11/09/2022]
Abstract
The distribution of valence electrons in metals usually follows the symmetry of the underlying ionic lattice. Modulations of this distribution often occur when those electrons are not stable with respect to a new electronic order, such as spin or charge density waves. Electron density waves have been observed in many families of superconductors, and are often considered to be essential for superconductivity to exist. Recent measurements seem to show that the properties of the iron pnictides are in good agreement with band structure calculations that do not include additional ordering, implying no relation between density waves and superconductivity in these materials. Here we report that the electronic structure of Ba(1-x)K(x)Fe(2)As(2) is in sharp disagreement with those band structure calculations, and instead reveals a reconstruction characterized by a (pi, pi) wavevector. This electronic order coexists with superconductivity and persists up to room temperature (300 K).
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Affiliation(s)
- V B Zabolotnyy
- Institute for Solid State Research, IFW-Dresden, PO Box 270116, 01171 Dresden, Germany
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18
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Rader O, Varykhalov A, Sánchez-Barriga J, Marchenko D, Rybkin A, Shikin AM. Is there a rashba effect in graphene on 3d ferromagnets? Phys Rev Lett 2009; 102:057602. [PMID: 19257554 DOI: 10.1103/physrevlett.102.057602] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2008] [Indexed: 05/27/2023]
Abstract
Graphene is considered a candidate material for spintronics. Recently, graphene grown on Ni(111) has been reported to show a Rashba effect which depends on the magnetization. By spin- and angle-resolved photoelectron spectroscopy, we investigate the preconditions for such an effect for graphene on Ni as well as on Co which has a approximately 3x larger 3d magnetic moment: (i) spin polarization or (ii) exchange splitting of graphene pi states in normal emission geometry, and (iii) Rashba-type spin-orbit splitting off normal. As none of these are found to be of considerable size, the reported effect is neither Rashba-type, nor due to the spin-orbit coupling, nor involving the electron spin.
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Affiliation(s)
- O Rader
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Strasse 15, D-12489 Berlin, Germany
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19
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Varykhalov A, Sánchez-Barriga J, Shikin AM, Gudat W, Eberhardt W, Rader O. Quantum cavity for spin due to spin-orbit interaction at a metal boundary. Phys Rev Lett 2008; 101:256601. [PMID: 19113734 DOI: 10.1103/physrevlett.101.256601] [Citation(s) in RCA: 3] [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: 04/07/2008] [Indexed: 05/27/2023]
Abstract
A quantum cavity for spin is created using a tungsten crystal as substrate of high nuclear charge and breaking the structural inversion symmetry through deposition of a gold quantum film. Spin- and angle-resolved photoelectron spectroscopy shows directly that quantum-well states and the "matrioshka" or Russian nested doll Fermi surface of the gold film are spin polarized and spin-orbit split up to a thickness of at least nine atomic layers. Ferromagnetic materials or external magnetic fields are not required, and the quantum film does not need to possess a high atomic number as analogous results with silver show.
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Affiliation(s)
- A Varykhalov
- Helmholtz-Zentrum für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Strasse 15, D-12489 Berlin, Germany
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20
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Varykhalov A, Sánchez-Barriga J, Shikin AM, Biswas C, Vescovo E, Rybkin A, Marchenko D, Rader O. Electronic and magnetic properties of quasifreestanding graphene on Ni. Phys Rev Lett 2008; 101:157601. [PMID: 18999644 DOI: 10.1103/physrevlett.101.157601] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2008] [Indexed: 05/27/2023]
Abstract
For the purpose of recovering the intriguing electronic properties of freestanding graphene at a solid surface, graphene self-organized on a Au monolayer on Ni(111) is prepared and characterized by scanning tunneling microscopy. Angle-resolved photoemission reveals a gapless linear pi-band dispersion near K[over] as a fingerprint of strictly monolayer graphene and a Dirac crossing energy equal to the Fermi energy (EF) within 25 meV meaning charge neutrality. Spin resolution shows a Rashba effect on the pi states with a large (approximately 13 meV) spin-orbit splitting up to EF which is independent of k.
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Affiliation(s)
- A Varykhalov
- BESSY, Albert-Einstein-Str. 15, D-12489 Berlin, Germany
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21
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Shikin AM, Varykhalov A, Prudnikova GV, Usachov D, Adamchuk VK, Yamada Y, Riley JD, Rader O. Origin of spin-orbit splitting for monolayers of au and ag on w(110) and mo(110). Phys Rev Lett 2008; 100:057601. [PMID: 18352430 DOI: 10.1103/physrevlett.100.057601] [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: 05/03/2007] [Indexed: 05/26/2023]
Abstract
Spin-orbit coupling can give rise to spin-split electronic states without a ferromagnet or an external magnetic field. We create large spin-orbit splittings in a Au and Ag monolayer on W(110) and show that the size of the splitting does not depend on the atomic number of the Au or Ag overlayer but of the W substrate. Spin- and angle-resolved photoemission and Fermi-surface scans reveal that the overlayer states acquire spin polarization through spin-dependent overlayer-substrate hybridization.
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Affiliation(s)
- A M Shikin
- Institute of Physics, St. Petersburg State University, St. Petersburg, 198504, Russia
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22
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Varykhalov A, Shikin AM, Gudat W, Moras P, Grazioli C, Carbone C, Rader O. Probing the ground state electronic structure of a correlated electron system by quantum well states: Ag/Ni(111). Phys Rev Lett 2005; 95:247601. [PMID: 16384423 DOI: 10.1103/physrevlett.95.247601] [Citation(s) in RCA: 3] [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: 04/17/2005] [Indexed: 05/05/2023]
Abstract
The ground state electronic properties of the strongly correlated transition metal Ni are usually not accessible from the excitation spectra measured in photoelectron spectroscopy. We show that the bottom of the Ni d band along [111] can be probed through the energy dependence of the phase of quantum-well states in Ag/Ni(111). Our model description of the quantum-well energies measured by angle-resolved photoemission determines the bottom of the empty set 1 d band of Ni as 2.6 eV, in full agreement with standard local density theory and at variance with the values of 1.7-1.8 eV from direct angle-resolved photoemission experiments of Ni.
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Affiliation(s)
- A Varykhalov
- BESSY, Albert-Einstein-Strasse 15, D-12489 Berlin, Germany
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23
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Shikin AM, Varykhalov A, Prudnikova GV, Adamchuk VK, Gudat W, Rader O. Photoemission from stepped W(110): initial or final state effect? Phys Rev Lett 2004; 93:146802. [PMID: 15524825 DOI: 10.1103/physrevlett.93.146802] [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: 03/09/2004] [Indexed: 05/24/2023]
Abstract
The electronic structure of the (110)-oriented terraces of stepped W(331) and W(551) is compared to the one of flat W(110) using angle-resolved photoemission. We identify a surface-localized state which develops perpendicular to the steps into a repeated band structure with the periodicity of the step superlattices. It is shown that a final-state diffraction process rather than an initial-state superlattice effect is the origin of the observed behavior and why it does not affect the entire band structure.
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Affiliation(s)
- A M Shikin
- BESSY, Albert-Einstein-Str. 15, D-12489 Berlin, Germany
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