1
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Brinkman SS, Tan XL, Brekke B, Mathisen AC, Finnseth Ø, Schenk RJ, Hagiwara K, Huang MJ, Buck J, Kalläne M, Hoesch M, Rossnagel K, Ou Yang KH, Lin MT, Shu GJ, Chen YJ, Tusche C, Bentmann H. Chirality-Driven Orbital Angular Momentum and Circular Dichroism in CoSi. PHYSICAL REVIEW LETTERS 2024; 132:196402. [PMID: 38804933 DOI: 10.1103/physrevlett.132.196402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/05/2024] [Accepted: 03/20/2024] [Indexed: 05/29/2024]
Abstract
Chiral crystals and molecules were recently predicted to form an intriguing platform for unconventional orbital physics. Here, we report the observation of chirality-driven orbital textures in the bulk electronic structure of CoSi, a prototype member of the cubic B20 family of chiral crystals. Using circular dichroism in soft x-ray angle-resolved photoemission, we demonstrate the formation of a bulk orbital-angular-momentum texture and monopolelike orbital-momentum locking that depends on crystal handedness. We introduce the intrinsic chiral circular dichroism, icCD, as a differential photoemission observable and a natural probe of chiral electron states. Our findings render chiral crystals promising for spin-orbitronics applications.
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Affiliation(s)
- Stefanie Suzanne Brinkman
- Center for Quantum Spintronics, Department of Physics, Norwegian University of Science and Technology, 7491 Trondheim, Norway
| | - Xin Liang Tan
- Center for Quantum Spintronics, Department of Physics, Norwegian University of Science and Technology, 7491 Trondheim, Norway
- Peter Grünberg Institut (PGI-6), Forschungszentrum Jülich, Jülich 52425, Germany
- Faculty of Physics, University of Duisburg-Essen, Duisburg 47057, Germany
| | - Bjørnulf Brekke
- Center for Quantum Spintronics, Department of Physics, Norwegian University of Science and Technology, 7491 Trondheim, Norway
| | - Anders Christian Mathisen
- Center for Quantum Spintronics, Department of Physics, Norwegian University of Science and Technology, 7491 Trondheim, Norway
| | - Øyvind Finnseth
- Department of Materials Science and Engineering, Norwegian University of Science and Technology, 7491 Trondheim, Norway
| | - Richard Justin Schenk
- Center for Quantum Spintronics, Department of Physics, Norwegian University of Science and Technology, 7491 Trondheim, Norway
| | - Kenta Hagiwara
- Peter Grünberg Institut (PGI-6), Forschungszentrum Jülich, Jülich 52425, Germany
- Faculty of Physics, University of Duisburg-Essen, Duisburg 47057, Germany
| | - Meng-Jie Huang
- Ruprecht Haensel Laboratory, Kiel University, 24098 Kiel, Germany
- Ruprecht Haensel Laboratory, DESY, 22607 Hamburg, Germany
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany
| | - Jens Buck
- Ruprecht Haensel Laboratory, Kiel University, 24098 Kiel, Germany
- Ruprecht Haensel Laboratory, DESY, 22607 Hamburg, Germany
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
| | - Matthias Kalläne
- Ruprecht Haensel Laboratory, Kiel University, 24098 Kiel, Germany
- Ruprecht Haensel Laboratory, DESY, 22607 Hamburg, Germany
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
| | - Moritz Hoesch
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany
| | - Kai Rossnagel
- Ruprecht Haensel Laboratory, Kiel University, 24098 Kiel, Germany
- Ruprecht Haensel Laboratory, DESY, 22607 Hamburg, Germany
- Deutsches Elektronen-Synchrotron DESY, Notkestraße 85, 22607 Hamburg, Germany
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, 24098 Kiel, Germany
| | - Kui-Hon Ou Yang
- Department of Physics, National Taiwan University, Taipei 10617, Taiwan
| | - Minn-Tsong Lin
- Department of Physics, National Taiwan University, Taipei 10617, Taiwan
- Institute of Atomic and Molecular Sciences, Academia Sinica, Taipei 10617, Taiwan
- Research Center for Applied Sciences, Academia Sinica, Taipei 11529, Taiwan
| | - Guo-Jiun Shu
- Department of Materials and Mineral Resources Engineering, National Taipei University of Technology, Taipei 10608, Taiwan
| | - Ying-Jiun Chen
- Peter Grünberg Institut (PGI-6), Forschungszentrum Jülich, Jülich 52425, Germany
- Faculty of Physics, University of Duisburg-Essen, Duisburg 47057, Germany
- Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Grünberg Institute, Forschungszentrum Jülich, 52425 Jülich, Germany
| | - Christian Tusche
- Peter Grünberg Institut (PGI-6), Forschungszentrum Jülich, Jülich 52425, Germany
- Faculty of Physics, University of Duisburg-Essen, Duisburg 47057, Germany
| | - Hendrik Bentmann
- Center for Quantum Spintronics, Department of Physics, Norwegian University of Science and Technology, 7491 Trondheim, Norway
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2
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Erhardt J, Schmitt C, Eck P, Schmitt M, Keßler P, Lee K, Kim T, Cacho C, Cojocariu I, Baranowski D, Feyer V, Veyrat L, Sangiovanni G, Claessen R, Moser S. Bias-Free Access to Orbital Angular Momentum in Two-Dimensional Quantum Materials. PHYSICAL REVIEW LETTERS 2024; 132:196401. [PMID: 38804920 DOI: 10.1103/physrevlett.132.196401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2024] [Revised: 03/06/2024] [Accepted: 04/08/2024] [Indexed: 05/29/2024]
Abstract
The demonstration of a topological band inversion constitutes the most elementary proof of a quantum spin Hall insulator (QSHI). On a fundamental level, such an inverted band gap is intrinsically related to the bulk Berry curvature, a gauge-invariant fingerprint of the wave function's quantum geometric properties in Hilbert space. Intimately tied to orbital angular momentum (OAM), the Berry curvature can be, in principle, extracted from circular dichroism in angle-resolved photoemission spectroscopy (CD-ARPES), were it not for interfering final state photoelectron emission channels that obscure the initial state OAM signature. Here, we outline a full-experimental strategy to avoid such interference artifacts and isolate the clean OAM from the CD-ARPES response. Bench-marking this strategy for the recently discovered atomic monolayer system indenene, we demonstrate its distinct QSHI character and establish CD-ARPES as a scalable bulk probe to experimentally classify the topology of two-dimensional quantum materials with time reversal symmetry.
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Affiliation(s)
- Jonas Erhardt
- Physikalisches Institut, Universität Würzburg, D-97074 Würzburg, Germany
- Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, D-97074 Würzburg, Germany
| | - Cedric Schmitt
- Physikalisches Institut, Universität Würzburg, D-97074 Würzburg, Germany
- Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, D-97074 Würzburg, Germany
| | - Philipp Eck
- Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, D-97074 Würzburg, Germany
- Institut für Theoretische Physik und Astrophysik, Universität Würzburg, D-97074 Würzburg, Germany
| | - Matthias Schmitt
- Physikalisches Institut, Universität Würzburg, D-97074 Würzburg, Germany
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, OX11 0DE, United Kingdom
| | - Philipp Keßler
- Physikalisches Institut, Universität Würzburg, D-97074 Würzburg, Germany
- Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, D-97074 Würzburg, Germany
| | - Kyungchan Lee
- Physikalisches Institut, Universität Würzburg, D-97074 Würzburg, Germany
- Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, D-97074 Würzburg, Germany
| | - Timur Kim
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, OX11 0DE, United Kingdom
| | - Cephise Cacho
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, OX11 0DE, United Kingdom
| | - Iulia Cojocariu
- Elettra-Sincrotrone, S.C.p.A, Trieste, 34149, Italy
- Peter Grünberg Institute (PGI-6), Forschungszentrum Jülich GmbH, Jülich, 52428, Germany
- Dipartimento di Fisica, Università degli Studi di Trieste, via A. Valerio 2, 34127 Trieste, Italy
| | - Daniel Baranowski
- Peter Grünberg Institute (PGI-6), Forschungszentrum Jülich GmbH, Jülich, 52428, Germany
| | - Vitaliy Feyer
- Peter Grünberg Institute (PGI-6), Forschungszentrum Jülich GmbH, Jülich, 52428, Germany
- Faculty of Physics and Center for Nanointegration Duisburg-Essen (CENIDE), Universität Duisburg-Essen, 47047 Duisburg, Germany
| | - Louis Veyrat
- Physikalisches Institut, Universität Würzburg, D-97074 Würzburg, Germany
- Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, D-97074 Würzburg, Germany
- Leibniz Institute for Solid State and Materials Research, IFW Dresden, D-01069 Dresden, Germany
- Laboratoire National des Champs Magnétiques Intenses, CNRS-INSA-UJF-UPS, UPR3228, 143 avenue de Rangueil, F-31400 Toulouse, France
| | - Giorgio Sangiovanni
- Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, D-97074 Würzburg, Germany
- Institut für Theoretische Physik und Astrophysik, Universität Würzburg, D-97074 Würzburg, Germany
| | - Ralph Claessen
- Physikalisches Institut, Universität Würzburg, D-97074 Würzburg, Germany
- Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, D-97074 Würzburg, Germany
| | - Simon Moser
- Physikalisches Institut, Universität Würzburg, D-97074 Würzburg, Germany
- Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, D-97074 Würzburg, Germany
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3
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Chen R, Sun HP, Gu M, Hua CB, Liu Q, Lu HZ, Xie XC. Layer Hall effect induced by hidden Berry curvature in antiferromagnetic insulators. Natl Sci Rev 2024; 11:nwac140. [PMID: 38264341 PMCID: PMC10804226 DOI: 10.1093/nsr/nwac140] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2022] [Revised: 07/05/2022] [Accepted: 07/07/2022] [Indexed: 01/25/2024] Open
Abstract
The layer Hall effect describes electrons spontaneously deflected to opposite sides at different layers, which has been experimentally reported in the MnBi2Te4 thin films under perpendicular electric fields. Here, we reveal a universal origin of the layer Hall effect in terms of the so-called hidden Berry curvature, as well as material design principles. Hence, it gives rise to zero Berry curvature in momentum space but non-zero layer-locked hidden Berry curvature in real space. We show that, compared to that of a trivial insulator, the layer Hall effect is significantly enhanced in antiferromagnetic topological insulators. Our universal picture provides a paradigm for revealing the hidden physics as a result of the interplay between the global and local symmetries, and can be generalized in various scenarios.
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Affiliation(s)
- Rui Chen
- Shenzhen Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology (SUSTech), Shenzhen 518055, China
- International Quantum Academy, Shenzhen 518048, China
| | - Hai-Peng Sun
- Shenzhen Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology (SUSTech), Shenzhen 518055, China
- Institute for Theoretical Physics and Astrophysics, University of Würzburg, Würzburg 97074, Germany
| | - Mingqiang Gu
- Shenzhen Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology (SUSTech), Shenzhen 518055, China
| | - Chun-Bo Hua
- School of Electronic and Information Engineering, Hubei University of Science and Technology, Xianning 437100, China
| | - Qihang Liu
- Shenzhen Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology (SUSTech), Shenzhen 518055, China
- Guangdong Provincial Key Laboratory of Computational Science and Material Design, Southern University of Science and Technology, Shenzhen 518055, China
| | - Hai-Zhou Lu
- Shenzhen Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology (SUSTech), Shenzhen 518055, China
- International Quantum Academy, Shenzhen 518048, China
- Shenzhen Key Laboratory of Quantum Science and Engineering, Shenzhen 518055, China
| | - X C Xie
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
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4
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Mazzola F, Brzezicki W, Mercaldo MT, Guarino A, Bigi C, Miwa JA, De Fazio D, Crepaldi A, Fujii J, Rossi G, Orgiani P, Chaluvadi SK, Chalil SP, Panaccione G, Jana A, Polewczyk V, Vobornik I, Kim C, Miletto-Granozio F, Fittipaldi R, Ortix C, Cuoco M, Vecchione A. Signatures of a surface spin-orbital chiral metal. Nature 2024; 626:752-758. [PMID: 38326617 PMCID: PMC10881390 DOI: 10.1038/s41586-024-07033-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2023] [Accepted: 01/05/2024] [Indexed: 02/09/2024]
Abstract
The relation between crystal symmetries, electron correlations and electronic structure steers the formation of a large array of unconventional phases of matter, including magneto-electric loop currents and chiral magnetism1-6. The detection of such hidden orders is an important goal in condensed-matter physics. However, until now, non-standard forms of magnetism with chiral electronic ordering have been difficult to detect experimentally7. Here we develop a theory for symmetry-broken chiral ground states and propose a methodology based on circularly polarized, spin-selective, angular-resolved photoelectron spectroscopy to study them. We use the archetypal quantum material Sr2RuO4 and reveal spectroscopic signatures that, despite being subtle, can be reconciled with the formation of spin-orbital chiral currents at the surface of the material8-10. As we shed light on these chiral regimes, our findings pave the way for a deeper understanding of ordering phenomena and unconventional magnetism.
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Affiliation(s)
- Federico Mazzola
- Department of Molecular Sciences and Nanosystems, Ca' Foscari University of Venice, Venice, Italy.
- Istituto Officina dei Materiali, Consiglio Nazionale delle Ricerche, Trieste, Italy.
| | - Wojciech Brzezicki
- Institute of Theoretical Physics, Jagiellonian University, Kraków, Poland
- International Centre for Interfacing Magnetism and Superconductivity with Topological Matter, Institute of Physics, Polish Academy of Sciences, Warsaw, Poland
| | | | - Anita Guarino
- Istituto SPIN, Consiglio Nazionale delle Ricerche, Fisciano, Italy
| | | | - Jill A Miwa
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University, Aarhus, Denmark
| | - Domenico De Fazio
- Department of Molecular Sciences and Nanosystems, Ca' Foscari University of Venice, Venice, Italy
| | | | - Jun Fujii
- Istituto Officina dei Materiali, Consiglio Nazionale delle Ricerche, Trieste, Italy
| | - Giorgio Rossi
- Istituto Officina dei Materiali, Consiglio Nazionale delle Ricerche, Trieste, Italy
- Dipartimento di Fisica, Università degli Studi di Milano, Milan, Italy
| | - Pasquale Orgiani
- Istituto Officina dei Materiali, Consiglio Nazionale delle Ricerche, Trieste, Italy
| | | | | | - Giancarlo Panaccione
- Istituto Officina dei Materiali, Consiglio Nazionale delle Ricerche, Trieste, Italy
| | - Anupam Jana
- Istituto Officina dei Materiali, Consiglio Nazionale delle Ricerche, Trieste, Italy
| | - Vincent Polewczyk
- Istituto Officina dei Materiali, Consiglio Nazionale delle Ricerche, Trieste, Italy
| | - Ivana Vobornik
- Istituto Officina dei Materiali, Consiglio Nazionale delle Ricerche, Trieste, Italy
| | - Changyoung Kim
- Department of Physics and Astronomy, Seoul National University, Seoul, Korea
| | | | | | - Carmine Ortix
- Dipartimento di Fisica "E. R. Caianiello", Università di Salerno, Fisciano, Italy
| | - Mario Cuoco
- Istituto SPIN, Consiglio Nazionale delle Ricerche, Fisciano, Italy.
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5
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Yang Q, Xiao J, Robredo I, Vergniory MG, Yan B, Felser C. Monopole-like orbital-momentum locking and the induced orbital transport in topological chiral semimetals. Proc Natl Acad Sci U S A 2023; 120:e2305541120. [PMID: 37983495 PMCID: PMC10691347 DOI: 10.1073/pnas.2305541120] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Accepted: 10/20/2023] [Indexed: 11/22/2023] Open
Abstract
The interplay between chirality and topology nurtures many exotic electronic properties. For instance, topological chiral semimetals display multifold chiral fermions that manifest nontrivial topological charge and spin texture. They are an ideal playground for exploring chirality-driven exotic physical phenomena. In this work, we reveal a monopole-like orbital-momentum locking texture on the three-dimensional Fermi surfaces of topological chiral semimetals with B20 structures (e.g., RhSi and PdGa). This orbital texture enables a large orbital Hall effect (OHE) and a giant orbital magnetoelectric (OME) effect in the presence of current flow. Different enantiomers exhibit the same OHE which can be converted to the spin Hall effect by spin-orbit coupling in materials. In contrast, the OME effect is chirality-dependent and much larger than its spin counterpart. Our work reveals the crucial role of orbital texture for understanding OHE and OME effects in topological chiral semimetals and paves the path for applications in orbitronics, spintronics, and enantiomer recognition.
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Affiliation(s)
- Qun Yang
- Max Planck Institute for Chemical Physics of Solids, Dresden01187, Germany
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot7610001, Israel
| | - Jiewen Xiao
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot7610001, Israel
| | - Iñigo Robredo
- Max Planck Institute for Chemical Physics of Solids, Dresden01187, Germany
- Donostia International Physics Center, Donostia-San Sebastian20018, Spain
| | - Maia G. Vergniory
- Max Planck Institute for Chemical Physics of Solids, Dresden01187, Germany
- Donostia International Physics Center, Donostia-San Sebastian20018, Spain
| | - Binghai Yan
- Department of Condensed Matter Physics, Weizmann Institute of Science, Rehovot7610001, Israel
| | - Claudia Felser
- Max Planck Institute for Chemical Physics of Solids, Dresden01187, Germany
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6
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De Beule C, Mele EJ. Berry Curvature Spectroscopy from Bloch Oscillations. PHYSICAL REVIEW LETTERS 2023; 131:196603. [PMID: 38000436 DOI: 10.1103/physrevlett.131.196603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Revised: 08/21/2023] [Accepted: 10/10/2023] [Indexed: 11/26/2023]
Abstract
Artificial crystals such as moiré superlattices can have a real-space periodicity much larger than the underlying atomic scale. This facilitates the presence of Bloch oscillations in the presence of a static electric field. We demonstrate that the optical response of such a system, when dressed with a static field, becomes resonant at the frequencies of Bloch oscillations, which are in the terahertz regime when the lattice constant is of the order of 10 nm. In particular, we show within a semiclassical band-projected theory that resonances in the dressed Hall conductivity are proportional to the lattice Fourier components of the Berry curvature. We illustrate our results with a low-energy model on an effective honeycomb lattice.
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Affiliation(s)
- Christophe De Beule
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
- Department of Physics and Materials Science, University of Luxembourg, L-1511 Luxembourg, Luxembourg
| | - E J Mele
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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7
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Fanciulli M, Bresteau D, Gaudin J, Dong S, Géneaux R, Ruchon T, Tcherbakoff O, Minár J, Heckmann O, Richter MC, Hricovini K, Beaulieu S. Ultrafast Hidden Spin Polarization Dynamics of Bright and Dark Excitons in 2H-WSe_{2}. PHYSICAL REVIEW LETTERS 2023; 131:066402. [PMID: 37625042 DOI: 10.1103/physrevlett.131.066402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/17/2023] [Accepted: 07/06/2023] [Indexed: 08/27/2023]
Abstract
We performed spin-, time- and angle-resolved extreme ultraviolet photoemission spectroscopy of excitons prepared by photoexcitation of inversion-symmetric 2H-WSe_{2} with circularly polarized light. The very short probing depth of XUV photoemission permits selective measurement of photoelectrons originating from the top-most WSe_{2} layer, allowing for direct measurement of hidden spin polarization of bright and momentum-forbidden dark excitons. Our results reveal efficient chiroptical control of bright excitons' hidden spin polarization. Following optical photoexcitation, intervalley scattering between nonequivalent K-K^{'} valleys leads to a decay of bright excitons' hidden spin polarization. Conversely, the ultrafast formation of momentum-forbidden dark excitons acts as a local spin polarization reservoir, which could be used for spin injection in van der Waals heterostructures involving multilayer transition metal dichalcogenides.
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Affiliation(s)
- Mauro Fanciulli
- Laboratoire de Physique des Matériaux et Surfaces, CY Cergy Paris Université, 95031 Cergy-Pontoise, France
- Université Paris-Saclay, CEA, CNRS, LIDYL, Gif-sur-Yvette, 91191, France
| | - David Bresteau
- Université Paris-Saclay, CEA, CNRS, LIDYL, Gif-sur-Yvette, 91191, France
| | - Jérôme Gaudin
- Université de Bordeaux-CNRS-CEA, CELIA, UMR5107, F33405 Talence, France
| | - Shuo Dong
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Romain Géneaux
- Université Paris-Saclay, CEA, CNRS, LIDYL, Gif-sur-Yvette, 91191, France
| | - Thierry Ruchon
- Université Paris-Saclay, CEA, CNRS, LIDYL, Gif-sur-Yvette, 91191, France
| | | | - Ján Minár
- University of West Bohemia, New Technologies Research Centre, 301 00 Plzeň, Czech Republic
| | - Olivier Heckmann
- Laboratoire de Physique des Matériaux et Surfaces, CY Cergy Paris Université, 95031 Cergy-Pontoise, France
- Université Paris-Saclay, CEA, CNRS, LIDYL, Gif-sur-Yvette, 91191, France
| | - Maria Christine Richter
- Laboratoire de Physique des Matériaux et Surfaces, CY Cergy Paris Université, 95031 Cergy-Pontoise, France
- Université Paris-Saclay, CEA, CNRS, LIDYL, Gif-sur-Yvette, 91191, France
| | - Karol Hricovini
- Laboratoire de Physique des Matériaux et Surfaces, CY Cergy Paris Université, 95031 Cergy-Pontoise, France
- Université Paris-Saclay, CEA, CNRS, LIDYL, Gif-sur-Yvette, 91191, France
| | - Samuel Beaulieu
- Université de Bordeaux-CNRS-CEA, CELIA, UMR5107, F33405 Talence, France
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8
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Shekhar S, Oh Y, Jeong JY, Choi Y, Cho D, Hong S. Nanoscale mapping of edge-state conductivity and charge-trap activity in topological insulators. MATERIALS HORIZONS 2023; 10:2245-2253. [PMID: 37014136 DOI: 10.1039/d2mh01259f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We report the nanoscale mapping of topological edge-state conductivity and the effects of charge-traps on conductivity in a Bi2Se3 multilayer film under ambient conditions. In this strategy, we applied an electric field perpendicular to the surface plane of Bi2Se3via a conducting probe to directly map the charge-trap densities and conductivities with a nanoscale resolution. The results showed that edge regions had one-dimensional characteristics with higher conductivities (two orders) and lower charge-trap densities (four orders) than those of flat surface regions where their conductivities and charge-traps were dominated by bulk effects. Additionally, edges showed an enhanced conductivity with an elevated electric field, possibly due to the creation of new topological states by stronger spin-Hall effects. Importantly, we observed ultra-high photoconductivity predominantly on edge regions compared with that of flat surface regions, which was attributed to the excitation of edge-state carriers by light. Since our method provides an important insight into the charge transport in topological insulators, it could be a significant advancement in the development of error-tolerant topotronic devices.
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Affiliation(s)
- Shashank Shekhar
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul 08826, Korea.
| | - Yuhyeon Oh
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul 08826, Korea.
| | - Jin-Young Jeong
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul 08826, Korea.
| | - Yoonji Choi
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul 08826, Korea.
| | - Duckhyung Cho
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul 08826, Korea.
| | - Seunghun Hong
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul 08826, Korea.
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9
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Schüler M, Schmitt T, Werner P. Probing magnetic orbitals and Berry curvature with circular dichroism in resonant inelastic X-ray scattering. NPJ QUANTUM MATERIALS 2023; 8:6. [PMID: 38666242 PMCID: PMC11041711 DOI: 10.1038/s41535-023-00538-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/28/2022] [Accepted: 01/04/2023] [Indexed: 04/28/2024]
Abstract
Resonant inelastic X-ray scattering (RIXS) can probe localized excitations at selected atoms in materials, including particle-hole transitions between the valence and conduction bands. These transitions are governed by fundamental properties of the corresponding Bloch wave functions, including orbital and magnetic degrees of freedom, and quantum geometric properties such as the Berry curvature. In particular, orbital angular momentum (OAM), which is closely linked to the Berry curvature, can exhibit a nontrivial momentum dependence. We demonstrate how information on such OAM textures can be extracted from the circular dichroism in RIXS. Based on accurate modeling with a first-principles treatment of the key ingredient-the light-matter interaction-we simulate dichroic RIXS spectra for the prototypical transition-metal dichalcogenide MoSe2 and the two-dimensional topological insulator 1T'-MoS2. Guided by an intuitive picture of the optical selection rules, we discuss how the momentum-dependent OAM manifests itself in the dichroic RIXS signal if one controls the momentum transfer. Our calculations are performed for typical experimental geometries and parameter regimes, and demonstrate the possibility of observing the predicted circular dichroism in forthcoming experiments. Thus, our work establishes a new avenue for observing Berry curvature and topological states in quantum materials.
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Affiliation(s)
- Michael Schüler
- Condensed Matter Theory Group, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
- Laboratory for Materials Simulations, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
- Department of Physics, University of Fribourg, 1700 Fribourg, Switzerland
| | - Thorsten Schmitt
- Photon Science Division, Swiss Light Source, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland
| | - Philipp Werner
- Department of Physics, University of Fribourg, 1700 Fribourg, Switzerland
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10
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Viñas Boström E, Parvini TS, McIver JW, Rubio A, Kusminskiy SV, Sentef MA. Direct Optical Probe of Magnon Topology in Two-Dimensional Quantum Magnets. PHYSICAL REVIEW LETTERS 2023; 130:026701. [PMID: 36706407 DOI: 10.1103/physrevlett.130.026701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2022] [Accepted: 12/12/2022] [Indexed: 06/18/2023]
Abstract
Controlling edge states of topological magnon insulators is a promising route to stable spintronics devices. However, to experimentally ascertain the topology of magnon bands is a challenging task. Here we derive a fundamental relation between the light-matter coupling and the quantum geometry of magnon states. This allows us to establish the two-magnon Raman circular dichroism as an optical probe of magnon topology in honeycomb magnets, in particular of the Chern number and the topological gap. Our results pave the way for interfacing light and topological magnons in functional quantum devices.
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Affiliation(s)
- Emil Viñas Boström
- Max Planck Institute for the Structure and Dynamics of Matter, Center for Free Electron Laser Science (CFEL), Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Tahereh Sadat Parvini
- Institute of Physics, University of Greifswald, Felix-Hausdorff-Strasse 6, Greifswald, 17489, Germany
| | - James W McIver
- Max Planck Institute for the Structure and Dynamics of Matter, Center for Free Electron Laser Science (CFEL), Luruper Chaussee 149, 22761 Hamburg, Germany
- Department of Physics, Columbia University, New York, New York 10027, USA
| | - Angel Rubio
- Max Planck Institute for the Structure and Dynamics of Matter, Center for Free Electron Laser Science (CFEL), Luruper Chaussee 149, 22761 Hamburg, Germany
- Center for Computational Quantum Physics, The Flatiron Institute, 162 Fifth Avenue, New York, New York 10010, USA
| | - Silvia Viola Kusminskiy
- Institute for Theoretical Solid State Physics, RWTH Aachen University, 52074 Aachen, Germany
- Max Planck Institute for the Science of Light, Staudtstrasse 2, PLZ 91058 Erlangen, Germany
| | - Michael A Sentef
- Max Planck Institute for the Structure and Dynamics of Matter, Center for Free Electron Laser Science (CFEL), Luruper Chaussee 149, 22761 Hamburg, Germany
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11
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Chen W, Gu M, Li J, Wang P, Liu Q. Role of Hidden Spin Polarization in Nonreciprocal Transport of Antiferromagnets. PHYSICAL REVIEW LETTERS 2022; 129:276601. [PMID: 36638296 DOI: 10.1103/physrevlett.129.276601] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/19/2022] [Revised: 08/04/2022] [Accepted: 11/22/2022] [Indexed: 06/17/2023]
Abstract
The discovery of hidden spin polarization (HSP) in centrosymmetric nonmagnetic crystals, i.e., spatially distributed spin polarization originated from local symmetry breaking, has promised an expanded material pool for future spintronics. However, the measurements of such exotic effects have been limited to subtle space- and momentum-resolved techniques, unfortunately, hindering their applications. Here, we theoretically predict macroscopic non-reciprocal transports induced by HSP when coupling another spatially distributed quantity, such as staggered local moments in a space-time PT-symmetric antiferromagnet. By using a four-band model Hamiltonian, we demonstrate that HSP plays a crucial role in determining the asymmetric bands with respect to opposite momenta. Such band asymmetry leads to non-reciprocal nonlinear conductivity, exemplified by tetragonal CuMnAs via first-principles calculations. We further provide the material design principles for large nonlinear conductivity, including two-dimensional nature, multiple band crossings near the Fermi level, and symmetry protected HSP. Our Letter not only reveals direct spintronic applications of HSP (such as Néel order detection), but also sheds light on finding observables of other hidden effects, such as hidden optical polarization and hidden Berry curvature.
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Affiliation(s)
- Weizhao Chen
- Shenzhen Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Mingqiang Gu
- Shenzhen Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Jiayu Li
- Shenzhen Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Panshuo Wang
- Shenzhen Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Qihang Liu
- Shenzhen Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
- Guangdong Provincial Key Laboratory of Computational Science and Material Design, Southern University of Science and Technology, Shenzhen 518055, China
- Shenzhen Key Laboratory of Advanced Quantum Functional Materials and Devices, Southern University of Science and Technology, Shenzhen 518055, China
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12
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Schusser J, Bentmann H, Ünzelmann M, Figgemeier T, Min CH, Moser S, Neu JN, Siegrist T, Reinert F. Assessing Nontrivial Topology in Weyl Semimetals by Dichroic Photoemission. PHYSICAL REVIEW LETTERS 2022; 129:246404. [PMID: 36563241 DOI: 10.1103/physrevlett.129.246404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 08/26/2022] [Accepted: 11/21/2022] [Indexed: 06/17/2023]
Abstract
The electronic structure of Weyl semimetals features Berry flux monopoles in the bulk and Fermi arcs at the surface. While angle-resolved photoelectron spectroscopy (ARPES) is successfully used to map the bulk and surface bands, it remains a challenge to explicitly resolve and pinpoint these topological features. Here we combine state-of-the-art photoemission theory and experiments over a wide range of excitation energies for the Weyl semimetals TaAs and TaP. Our results show that simple surface-band-counting schemes, proposed previously to identify nonzero Chern numbers, are ambiguous due to pronounced momentum-dependent spectral weight variations and the pronounced surface-bulk hybridization. Instead, our findings indicate that dichroic ARPES provides an improved approach to identify Fermi arcs but requires an accurate description of the photoelectron final state.
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Affiliation(s)
- J Schusser
- Experimentelle Physik VII and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, D-97074 Würzburg, Germany
| | - H Bentmann
- Experimentelle Physik VII and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, D-97074 Würzburg, Germany
| | - M Ünzelmann
- Experimentelle Physik VII and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, D-97074 Würzburg, Germany
| | - T Figgemeier
- Experimentelle Physik VII and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, D-97074 Würzburg, Germany
| | - C-H Min
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, Kiel, Germany
- Ruprecht Haensel Laboratory, Kiel University and DESY, Kiel, Germany
| | - S Moser
- Experimentelle Physik IV and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, D-97074 Würzburg, Germany
| | - J N Neu
- National High Magnetic Field Laboratory, Tallahassee, Florida 32310, USA
- Nuclear Nonproliferation Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA
| | - T Siegrist
- National High Magnetic Field Laboratory, Tallahassee, Florida 32310, USA
- Department of Chemical and Biomedical Engineering, FAMU-FSU College of Engineering, Tallahassee, Florida 32310, USA
| | - F Reinert
- Experimentelle Physik VII and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, D-97074 Würzburg, Germany
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13
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Caruso F, Schebek M, Pan Y, Vona C, Draxl C. Chirality of Valley Excitons in Monolayer Transition-Metal Dichalcogenides. J Phys Chem Lett 2022; 13:5894-5899. [PMID: 35729685 DOI: 10.1021/acs.jpclett.2c01034] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
By enabling control of valley degrees of freedom in transition-metal dichalcogenides, valley-selective circular dichroism has become a key concept in valleytronics. Herein, we show that valley excitons, bound electron-hole pairs formed at the K or K̅ valleys upon absorption of circularly polarized light, are chiral quasiparticles characterized by a finite orbital angular momentum (OAM). We further formulate an ab initio many-body theory of valley-selective circular dichroism and valley excitons based on the Bethe-Salpeter equation. Besides governing the interaction with circularly polarized light, the OAM confers upon excitons a finite magnetization that manifests itself through an excitonic Zeeman splitting upon interaction with external magnetic fields. The good agreement between our ab initio calculations and recent experimental measurements of the exciton Zeeman shifts corroborates this picture, indicating that valley excitons can carry angular momentum even in their singlet state.
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Affiliation(s)
- Fabio Caruso
- Institut für Theoretische Physik und Astrophysik, Christian-Albrechts-Universität zu Kiel, 24118 Kiel, Germany
| | - Maximilian Schebek
- Institut für Physik and IRIS Adlershof, Humboldt-Universität zu Berlin, 12489 Berlin, Germany
| | - Yiming Pan
- Institut für Theoretische Physik und Astrophysik, Christian-Albrechts-Universität zu Kiel, 24118 Kiel, Germany
| | - Cecilia Vona
- Institut für Physik and IRIS Adlershof, Humboldt-Universität zu Berlin, 12489 Berlin, Germany
| | - Claudia Draxl
- Institut für Physik and IRIS Adlershof, Humboldt-Universität zu Berlin, 12489 Berlin, Germany
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14
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Abstract
Optically excited systems can host unprecedented phenomena and reveal key information. The spin-channel physics in the photoexcited dynamics of quantum matter remains largely unexplored. This study finds the topological surface state under contemporary time-resolved pump-probe spectroscopy an exceptionally capable platform in this regard. Spin signals exhibit interesting tornado-like spiral patterns, and the unusual topological optical activity can be indicative of spintronic applications. This exemplifies a purely nonequilibrium topological winding phenomenon, where all the hidden helicity factors in the light–matter-coupled system are robustly encoded. These results open a direction of nonequilibrium topological spin states in quantum materials. Nonequilibrium quantum dynamics of many-body systems is the frontier of condensed matter physics; recent advances in various time-resolved spectroscopic techniques continue to reveal rich phenomena. Angle-resolved photoemission spectroscopy (ARPES) as one powerful technique can resolve electronic energy, momentum, and spin along the time axis after excitation. However, dynamics of spin textures in momentum space remains mostly unexplored. Here, we demonstrate theoretically that the photoexcited surface state of genuine or magnetically doped topological insulators shows intriguing topological spin textures (i.e., tornado-like patterns) in the spin-resolved ARPES. We systematically reveal its origin as a unique nonequilibrium photoinduced topological winding phenomenon. As all intrinsic and extrinsic topological helicity factors of both material and light are embedded in a robust and delicate manner, the tornado patterns not only allow a remarkable tomography of such important system information, but also enable various unique dichroic topological switchings of the momentum-space spin texture. These results open a direction of nonequilibrium topological spin states in quantum materials.
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15
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Sun X, Qin F, Huang J, Zhou L, Li Z, Bi X, Ao L, Duan S, Cheng F, Qiu C, Lu Y, Lu H, Gou H, Yuan H. Emergent Fabry-Pérot Interference for Light-Matter Interaction in van der Waals WS 2/SiP 2 Heterostructures. ACS APPLIED MATERIALS & INTERFACES 2022; 14:7464-7470. [PMID: 35099944 DOI: 10.1021/acsami.1c22768] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/14/2023]
Abstract
Fabry-Pérot interference plays an important role in modulating the spectral intensity of optical response originating from light-matter interactions. Examples of such interference occurring in the substrate as the resonating cavity have been demonstrated and probed by two-dimensional layered materials. Similarly, the Fabry-Pérot interference can occur and modulate the optical response in the heterostructure; however, this remains elusive. Herein, we observe the Fabry-Pérot interference on photoluminescence (PL) and Raman spectra in monolayer WS2/SiP2 heterostructures by varying the thickness of bottom SiP2 from 2 to 193 nm, which serves as the Fabry-Pérot cavity. Both the intensities of the PL spectra and the E2g1 Raman mode of WS2/SiP2 heterostructures first decrease to almost zero while displaying an interference increase at a SiP2 thickness of 75 nm. Our findings clearly demonstrate the Fabry-Pérot interference in the optical response of heterostructures, providing crucial information to optimize the optical response and paving the way toward photodetector applications.
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Affiliation(s)
- Xiaojun Sun
- College of Engineering and Applied Sciences, National Laboratory of Solid State Microstructures and Jiangsu Key Laboratory of Artificial Functional Materials, Nanjing University, Nanjing 210000, China
| | - Feng Qin
- College of Engineering and Applied Sciences, National Laboratory of Solid State Microstructures and Jiangsu Key Laboratory of Artificial Functional Materials, Nanjing University, Nanjing 210000, China
| | - Junwei Huang
- College of Engineering and Applied Sciences, National Laboratory of Solid State Microstructures and Jiangsu Key Laboratory of Artificial Functional Materials, Nanjing University, Nanjing 210000, China
| | - Ling Zhou
- College of Engineering and Applied Sciences, National Laboratory of Solid State Microstructures and Jiangsu Key Laboratory of Artificial Functional Materials, Nanjing University, Nanjing 210000, China
| | - Zeya Li
- College of Engineering and Applied Sciences, National Laboratory of Solid State Microstructures and Jiangsu Key Laboratory of Artificial Functional Materials, Nanjing University, Nanjing 210000, China
| | - Xiangyu Bi
- College of Engineering and Applied Sciences, National Laboratory of Solid State Microstructures and Jiangsu Key Laboratory of Artificial Functional Materials, Nanjing University, Nanjing 210000, China
| | - Lingyi Ao
- College of Engineering and Applied Sciences, National Laboratory of Solid State Microstructures and Jiangsu Key Laboratory of Artificial Functional Materials, Nanjing University, Nanjing 210000, China
| | - Siyu Duan
- College of Engineering and Applied Sciences, National Laboratory of Solid State Microstructures and Jiangsu Key Laboratory of Artificial Functional Materials, Nanjing University, Nanjing 210000, China
| | - Fanghua Cheng
- College of Engineering and Applied Sciences, National Laboratory of Solid State Microstructures and Jiangsu Key Laboratory of Artificial Functional Materials, Nanjing University, Nanjing 210000, China
| | - Caiyu Qiu
- College of Engineering and Applied Sciences, National Laboratory of Solid State Microstructures and Jiangsu Key Laboratory of Artificial Functional Materials, Nanjing University, Nanjing 210000, China
| | - Yangfan Lu
- College of Materials Science and Engineering, National Engineering Research Center for Magnesium Alloys, Chongqing University, Chongqing 400030, China
| | - Hong Lu
- College of Engineering and Applied Sciences, National Laboratory of Solid State Microstructures and Jiangsu Key Laboratory of Artificial Functional Materials, Nanjing University, Nanjing 210000, China
| | - Huiyang Gou
- Center for High Pressure Science and Technology Advanced Research, Beijing 100094, China
| | - Hongtao Yuan
- College of Engineering and Applied Sciences, National Laboratory of Solid State Microstructures and Jiangsu Key Laboratory of Artificial Functional Materials, Nanjing University, Nanjing 210000, China
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16
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Sohn B, Lee E, Park SY, Kyung W, Hwang J, Denlinger JD, Kim M, Kim D, Kim B, Ryu H, Huh S, Oh JS, Jung JK, Oh D, Kim Y, Han M, Noh TW, Yang BJ, Kim C. Sign-tunable anomalous Hall effect induced by two-dimensional symmetry-protected nodal structures in ferromagnetic perovskite thin films. NATURE MATERIALS 2021; 20:1643-1649. [PMID: 34608283 DOI: 10.1038/s41563-021-01101-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2019] [Accepted: 08/11/2021] [Indexed: 06/13/2023]
Abstract
Magnetism and spin-orbit coupling are two quintessential ingredients underlying topological transport phenomena in itinerant ferromagnets. When spin-polarized bands support nodal points/lines with band degeneracy that can be lifted by spin-orbit coupling, the nodal structures become a source of Berry curvature, leading to a large anomalous Hall effect. However, two-dimensional systems can possess stable nodal structures only when proper crystalline symmetry exists. Here we show that two-dimensional spin-polarized band structures of perovskite oxides generally support symmetry-protected nodal lines and points that govern both the sign and the magnitude of the anomalous Hall effect. To demonstrate this, we performed angle-resolved photoemission studies of ultrathin films of SrRuO3, a representative metallic ferromagnet with spin-orbit coupling. We show that the sign-changing anomalous Hall effect upon variation in the film thickness, magnetization and chemical potential can be well explained by theoretical models. Our work may facilitate new switchable devices based on ferromagnetic ultrathin films.
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Affiliation(s)
- Byungmin Sohn
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, Korea
| | - Eunwoo Lee
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, Korea
- Center for Theoretical Physics, Seoul National University, Seoul, Korea
| | - Se Young Park
- Department of Physics and Origin of Matter and Evolution of Galaxies (OMEG) Institute, Soongsil University, Seoul, Korea.
| | - Wonshik Kyung
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, Korea
| | - Jinwoong Hwang
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, USA
| | | | - Minsoo Kim
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, Korea
| | - Donghan Kim
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, Korea
| | - Bongju Kim
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, Korea
| | - Hanyoung Ryu
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, Korea
| | - Soonsang Huh
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, Korea
| | - Ji Seop Oh
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, Korea
| | - Jong Keun Jung
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, Korea
| | - Dongjin Oh
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, Korea
| | - Younsik Kim
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, Korea
| | - Moonsup Han
- Department of Physics, University of Seoul, Seoul, Korea
| | - Tae Won Noh
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, Korea
- Department of Physics and Astronomy, Seoul National University, Seoul, Korea
| | - Bohm-Jung Yang
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, Korea.
- Department of Physics and Astronomy, Seoul National University, Seoul, Korea.
- Center for Theoretical Physics, Seoul National University, Seoul, Korea.
| | - Changyoung Kim
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul, Korea.
- Department of Physics and Astronomy, Seoul National University, Seoul, Korea.
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17
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Design and realization of topological Dirac fermions on a triangular lattice. Nat Commun 2021; 12:5396. [PMID: 34518548 PMCID: PMC8438025 DOI: 10.1038/s41467-021-25627-y] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2021] [Accepted: 08/22/2021] [Indexed: 11/17/2022] Open
Abstract
Large-gap quantum spin Hall insulators are promising materials for room-temperature applications based on Dirac fermions. Key to engineer the topologically non-trivial band ordering and sizable band gaps is strong spin-orbit interaction. Following Kane and Mele’s original suggestion, one approach is to synthesize monolayers of heavy atoms with honeycomb coordination accommodated on templates with hexagonal symmetry. Yet, in the majority of cases, this recipe leads to triangular lattices, typically hosting metals or trivial insulators. Here, we conceive and realize “indenene”, a triangular monolayer of indium on SiC exhibiting non-trivial valley physics driven by local spin-orbit coupling, which prevails over inversion-symmetry breaking terms. By means of tunneling microscopy of the 2D bulk we identify the quantum spin Hall phase of this triangular lattice and unveil how a hidden honeycomb connectivity emerges from interference patterns in Bloch px ± ipy-derived wave functions. Atomic monolayers of large-gap quantum spin Hall insulators are challenging to synthesize. Here, the authors realize massive Dirac fermions emerging from Bloch wave-function interference on a triangular lattice and achieve topologically non-trivial domains with unprecedented spatial extension.
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18
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Ünzelmann M, Bentmann H, Figgemeier T, Eck P, Neu JN, Geldiyev B, Diekmann F, Rohlf S, Buck J, Hoesch M, Kalläne M, Rossnagel K, Thomale R, Siegrist T, Sangiovanni G, Sante DD, Reinert F. Momentum-space signatures of Berry flux monopoles in the Weyl semimetal TaAs. Nat Commun 2021; 12:3650. [PMID: 34131129 PMCID: PMC8206138 DOI: 10.1038/s41467-021-23727-3] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2020] [Accepted: 05/12/2021] [Indexed: 11/16/2022] Open
Abstract
Since the early days of Dirac flux quantization, magnetic monopoles have been sought after as a potential corollary of quantized electric charge. As opposed to magnetic monopoles embedded into the theory of electromagnetism, Weyl semimetals (WSM) exhibit Berry flux monopoles in reciprocal parameter space. As a function of crystal momentum, such monopoles locate at the crossing point of spin-polarized bands forming the Weyl cone. Here, we report momentum-resolved spectroscopic signatures of Berry flux monopoles in TaAs as a paradigmatic WSM. We carried out angle-resolved photoelectron spectroscopy at bulk-sensitive soft X-ray energies (SX-ARPES) combined with photoelectron spin detection and circular dichroism. The experiments reveal large spin- and orbital-angular-momentum (SAM and OAM) polarizations of the Weyl-fermion states, resulting from the broken crystalline inversion symmetry in TaAs. Supported by first-principles calculations, our measurements image signatures of a topologically non-trivial winding of the OAM at the Weyl nodes and unveil a chirality-dependent SAM of the Weyl bands. Our results provide directly bulk-sensitive spectroscopic support for the non-trivial band topology in the WSM TaAs, promising to have profound implications for the study of quantum-geometric effects in solids. Weyl semimetals exhibit Berry flux monopoles in momentum-space, but direct experimental evidence has remained elusive. Here, the authors reveal topologically non-trivial winding of the orbital-angular-momentum at the Weyl nodes and a chirality-dependent spin-angular-momentum of the Weyl bands, as a direct signature of the Berry flux monopoles in TaAs.
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Affiliation(s)
- M Ünzelmann
- Experimentelle Physik VII and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, Würzburg, Germany
| | - H Bentmann
- Experimentelle Physik VII and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, Würzburg, Germany.
| | - T Figgemeier
- Experimentelle Physik VII and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, Würzburg, Germany
| | - P Eck
- Theoretische Physik I, Universität Würzburg, Würzburg, Germany
| | - J N Neu
- Department of Chemical and Biomedical Engineering, FAMU-FSU College of Engineering, Tallahassee, FL, USA.,National High Magnetic Field Laboratory, Tallahassee, FL, USA
| | - B Geldiyev
- Experimentelle Physik VII and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, Würzburg, Germany
| | - F Diekmann
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, Kiel, Germany.,Ruprecht Haensel Laboratory, Kiel University and DESY, Kiel, Germany
| | - S Rohlf
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, Kiel, Germany.,Ruprecht Haensel Laboratory, Kiel University and DESY, Kiel, Germany
| | - J Buck
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, Kiel, Germany.,Ruprecht Haensel Laboratory, Kiel University and DESY, Kiel, Germany
| | - M Hoesch
- Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany
| | - M Kalläne
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, Kiel, Germany.,Ruprecht Haensel Laboratory, Kiel University and DESY, Kiel, Germany
| | - K Rossnagel
- Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, Kiel, Germany.,Ruprecht Haensel Laboratory, Kiel University and DESY, Kiel, Germany.,Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany
| | - R Thomale
- Theoretische Physik I, Universität Würzburg, Würzburg, Germany
| | - T Siegrist
- Department of Chemical and Biomedical Engineering, FAMU-FSU College of Engineering, Tallahassee, FL, USA.,National High Magnetic Field Laboratory, Tallahassee, FL, USA
| | - G Sangiovanni
- Theoretische Physik I, Universität Würzburg, Würzburg, Germany
| | - D Di Sante
- Theoretische Physik I, Universität Würzburg, Würzburg, Germany.,Department of Physics and Astronomy, University of Bologna, Bologna, Italy.,Center for Computational Quantum Physics, Flatiron Institute, New York, NY, USA
| | - F Reinert
- Experimentelle Physik VII and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, Würzburg, Germany
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19
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Bao C, Zhang H, Zhang T, Wu X, Luo L, Zhou S, Li Q, Hou Y, Yao W, Liu L, Yu P, Li J, Duan W, Yao H, Wang Y, Zhou S. Experimental Evidence of Chiral Symmetry Breaking in Kekulé-Ordered Graphene. PHYSICAL REVIEW LETTERS 2021; 126:206804. [PMID: 34110212 DOI: 10.1103/physrevlett.126.206804] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2021] [Accepted: 03/30/2021] [Indexed: 06/12/2023]
Abstract
The low-energy excitations of graphene are relativistic massless Dirac fermions with opposite chiralities at valleys K and K^{'}. Breaking the chiral symmetry could lead to gap opening in analogy to dynamical mass generation in particle physics. Here we report direct experimental evidences of chiral symmetry breaking (CSB) from both microscopic and spectroscopic measurements in a Li-intercalated graphene. The CSB is evidenced by gap opening at the Dirac point, Kekulé-O type modulation, and chirality mixing near the gap edge. Our work opens up opportunities for investigating CSB related physics in a Kekulé-ordered graphene.
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Affiliation(s)
- Changhua Bao
- State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
| | - Hongyun Zhang
- State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
| | - Teng Zhang
- School of Information and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing 100081, People's Republic of China
| | - Xi Wu
- Shenzhen Geim Graphene Center and Institute of Materials Research, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, People's Republic of China
| | - Laipeng Luo
- State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
| | - Shaohua Zhou
- State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
| | - Qian Li
- State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
| | - Yanhui Hou
- School of Information and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing 100081, People's Republic of China
| | - Wei Yao
- State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
| | - Liwei Liu
- School of Information and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing 100081, People's Republic of China
| | - Pu Yu
- State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
- Frontier Science Center for Quantum Information, Beijing 100084, People's Republic of China
| | - Jia Li
- Shenzhen Geim Graphene Center and Institute of Materials Research, Tsinghua Shenzhen International Graduate School, Tsinghua University, Shenzhen 518055, People's Republic of China
| | - Wenhui Duan
- State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
- Frontier Science Center for Quantum Information, Beijing 100084, People's Republic of China
| | - Hong Yao
- Institute for Advanced Study, Tsinghua University, Beijing 100084, People's Republic of China
- Department of Physics, Stanford University, Stanford, California 94305, USA
| | - Yeliang Wang
- School of Information and Electronics, MIIT Key Laboratory for Low-Dimensional Quantum Structure and Devices, Beijing Institute of Technology, Beijing 100081, People's Republic of China
| | - Shuyun Zhou
- State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
- Frontier Science Center for Quantum Information, Beijing 100084, People's Republic of China
- Beijing Advanced Innovation Center for Future Chip, Beijing 100084, People's Republic of China
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20
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Ab Initio Theory of Photoemission from Graphene. NANOMATERIALS 2021; 11:nano11051212. [PMID: 34063600 PMCID: PMC8147655 DOI: 10.3390/nano11051212] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/30/2021] [Revised: 04/28/2021] [Accepted: 04/30/2021] [Indexed: 11/17/2022]
Abstract
Angle-resolved photoemission from monolayer and bilayer graphene is studied based on an ab initio one-step theory. The outgoing photoelectron is represented by the time-reversed low energy electron diffraction (LEED) state ΦLEED*, which is calculated using a scattering theory formulated in terms of augmented plane waves. A strong enhancement of the emission intensity is found to occur around the scattering resonances. The effect of the photoelectron scattering by the underlying substrate on the polarization dependence of the photocurrent is discussed. The constant initial state spectra I(k||,ℏω) are compared to electron transmission spectra T(E) of graphene, and the spatial structure of the outgoing waves is analyzed. It turns out that the emission intensity variations do not correlate with the structure of the T(E) spectra and are caused by rather subtle interference effects. Earlier experimental observations of the photon energy and polarization dependence of the emission intensity I(k||,ℏω) are well reproduced within the dipole approximation, and the Kohn-Sham eigenstates are found to provide a quite reasonable description of the photoemission final states.
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21
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Hedayat H, Bugini D, Yi H, Chen C, Zhou X, Cerullo G, Dallera C, Carpene E. Ultrafast evolution of bulk, surface and surface resonance states in photoexcited [Formula: see text]. Sci Rep 2021; 11:4924. [PMID: 33649414 PMCID: PMC7921141 DOI: 10.1038/s41598-021-83848-z] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Accepted: 02/05/2021] [Indexed: 11/09/2022] Open
Abstract
We use circular dichroism (CD) in time- and angle-resolved photoemission spectroscopy (trARPES) to measure the femtosecond charge dynamics in the topological insulator (TI) [Formula: see text]. We detect clear CD signatures from topological surface states (TSS) and surface resonance (SR) states. In time-resolved measurements, independently from the pump polarization or intensity, the CD shows a dynamics which provides access to the unexplored electronic evolution in unoccupied states of [Formula: see text]. In particular, we are able to disentangle the unpolarized electron dynamics in the bulk states from the spin-textured TSS and SR states on the femtosecond timescale. Our study demonstrates that photoexcitation mainly involves the bulk states and is followed by sub-picosecond transport to the surface. This provides essential details on intra- and interband scattering in the relaxation process of TSS and SR states. Our results reveal the significant role of SRs in the subtle ultrafast interaction between bulk and surface states of TIs.
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Affiliation(s)
- Hamoon Hedayat
- IFN-CNR, Dipartimento di Fisica, Politecnico di Milano, 20133 Milan, Italy
- Dipartimento di Fisica, Politecnico di Milano, 20133 Milan, Italy
| | - Davide Bugini
- Dipartimento di Fisica, Politecnico di Milano, 20133 Milan, Italy
| | - Hemian Yi
- National Lab for Superconductivity, Institute of Physics, Chinese Academy of Science, Beijing, 100190 China
| | - Chaoyu Chen
- National Lab for Superconductivity, Institute of Physics, Chinese Academy of Science, Beijing, 100190 China
| | - Xingjiang Zhou
- National Lab for Superconductivity, Institute of Physics, Chinese Academy of Science, Beijing, 100190 China
| | - Giulio Cerullo
- Dipartimento di Fisica, Politecnico di Milano, 20133 Milan, Italy
| | - Claudia Dallera
- Dipartimento di Fisica, Politecnico di Milano, 20133 Milan, Italy
| | - Ettore Carpene
- IFN-CNR, Dipartimento di Fisica, Politecnico di Milano, 20133 Milan, Italy
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22
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Cho S, Park JH, Huh S, Hong J, Kyung W, Park BG, Denlinger JD, Shim JH, Kim C, Park SR. Studying local Berry curvature in 2H-WSe 2 by circular dichroism photoemission utilizing crystal mirror plane. Sci Rep 2021; 11:1684. [PMID: 33462247 PMCID: PMC7814090 DOI: 10.1038/s41598-020-79672-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Accepted: 11/20/2020] [Indexed: 11/23/2022] Open
Abstract
It was recently reported that circular dichroism in angle-resolved photoemission spectroscopy (CD-ARPES) can be used to observe the Berry curvature in 2H-WSe2 (Cho et al. in Phys Rev Lett 121:186401, 2018). In that study, the mirror plane of the experiment was intentionally set to be perpendicular to the crystal mirror plane, such that the Berry curvature becomes a symmetric function about the experimental mirror plane. In the present study, we performed CD-ARPES on 2H-WSe2 with the crystal mirror plane taken as the experimental mirror plane. Within such an experimental constraint, two experimental geometries are possible for CD-ARPES. The Berry curvature distributions for the two geometries are expected to be antisymmetric about the experimental mirror plane and exactly opposite to each other. Our experimental CD intensities taken with the two geometries were found to be almost opposite near the corners of the 2D projected hexagonal Brillouin zone (BZ) and were almost identical near the center of the BZ. This observation is well explained by taking the Berry curvature or the atomic orbital angular momentum (OAM) into account. The Berry curvature (or OAM) contribution to the CD intensities can be successfully extracted through a comparison of the CD-ARPES data for the two experimental geometries. Thus, the CD-ARPES experimental procedure described provides a method for mapping Berry curvature in the momentum space of topological materials, such as Weyl semimetals.
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Affiliation(s)
- Soohyun Cho
- State Key Laboratory of Functional Materials for Informatics, Shanghai Institute of Microsystem and Information Technology (SIMIT), Chinese Academy of Sciences, Shanghai, 200050, People's Republic of China.,Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 08826, Republic of Korea.,CAS Center for Excellence in Superconducting Electronics (CENSE), Shanghai, 200050, People's Republic of China
| | - Jin-Hong Park
- Department of Physics, Sungkyunkwan University, Suwon, 16419, Republic of Korea
| | - Soonsang Huh
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 08826, Republic of Korea.,Department of Physics and Astronomy, Seoul National University (SNU), Seoul, 08826, Republic of Korea
| | - Jisook Hong
- The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Wonshik Kyung
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 08826, Republic of Korea
| | - Byeong-Gyu Park
- Pohang Accelerator Laboratory, Pohang University of Science and Technology, Pohang, 37673, Republic of Korea
| | - J D Denlinger
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Ji Hoon Shim
- Department of Chemistry, Pohang University of Science and Technology, Pohang, 37673, Republic of Korea.,Department of Physics and Division of Advanced Nuclear Engineering, Pohang University of Science and Technology, Pohang, 37673, Republic of Korea
| | - Changyoung Kim
- Center for Correlated Electron Systems, Institute for Basic Science (IBS), Seoul, 08826, Republic of Korea. .,Department of Physics and Astronomy, Seoul National University (SNU), Seoul, 08826, Republic of Korea.
| | - Seung Ryong Park
- Department of Physics, Incheon National University, Incheon, 22012, Republic of Korea.
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23
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Beaulieu S, Schusser J, Dong S, Schüler M, Pincelli T, Dendzik M, Maklar J, Neef A, Ebert H, Hricovini K, Wolf M, Braun J, Rettig L, Minár J, Ernstorfer R. Revealing Hidden Orbital Pseudospin Texture with Time-Reversal Dichroism in Photoelectron Angular Distributions. PHYSICAL REVIEW LETTERS 2020; 125:216404. [PMID: 33274965 DOI: 10.1103/physrevlett.125.216404] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 10/13/2020] [Indexed: 06/12/2023]
Abstract
We performed angle-resolved photoemission spectroscopy (ARPES) of bulk 2H-WSe_{2} for different crystal orientations linked to each other by time-reversal symmetry. We introduce a new observable called time-reversal dichroism in photoelectron angular distributions (TRDAD), which quantifies the modulation of the photoemission intensity upon effective time-reversal operation. We demonstrate that the hidden orbital pseudospin texture leaves its imprint on TRDAD, due to multiple orbital interference effects in photoemission. Our experimental results are in quantitative agreement with both the tight-binding model and state-of-the-art fully relativistic calculations performed using the one-step model of photoemission. While spin-resolved ARPES probes the spin component of entangled spin-orbital texture in multiorbital systems, we unambiguously demonstrate that TRDAD reveals its orbital pseudospin texture counterpart.
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Affiliation(s)
- S Beaulieu
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
| | - J Schusser
- Laboratoire de Physique des Matériaux et Surfaces, CY Cergy Paris Université, 95031 Cergy-Pontoise, France
- New Technologies-Research Center, University of West Bohemia, 30614 Pilsen, Czech Republic
| | - S Dong
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
| | - M Schüler
- Stanford Institute for Materials and Energy Sciences (SIMES), SLAC National Accelerator Laboratory, Menlo Park, California 94025, USA
| | - T Pincelli
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
| | - M Dendzik
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
- Department of Applied Physics, KTH Royal Institute of Technology, Hannes Alfvéns väg 12, 114 19 Stockholm, Sweden
| | - J Maklar
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
| | - A Neef
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
| | - H Ebert
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 11, 81377 München, Germany
| | - K Hricovini
- Laboratoire de Physique des Matériaux et Surfaces, CY Cergy Paris Université, 95031 Cergy-Pontoise, France
- LIDYL, CEA, CNRS, Université Paris-Saclay, CEA Saclay, F-91191 Gif-sur-Yvette Cedex, France
| | - M Wolf
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
| | - J Braun
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 11, 81377 München, Germany
| | - L Rettig
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
| | - J Minár
- New Technologies-Research Center, University of West Bohemia, 30614 Pilsen, Czech Republic
| | - R Ernstorfer
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
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24
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Boyers E, Crowley PJD, Chandran A, Sushkov AO. Exploring 2D Synthetic Quantum Hall Physics with a Quasiperiodically Driven Qubit. PHYSICAL REVIEW LETTERS 2020; 125:160505. [PMID: 33124857 DOI: 10.1103/physrevlett.125.160505] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 09/13/2020] [Indexed: 06/11/2023]
Abstract
Quasiperiodically driven quantum systems are predicted to exhibit quantized topological properties, in analogy with the quantized transport properties of topological insulators. We use a single nitrogen-vacancy center in diamond to experimentally study a synthetic quantum Hall effect with a two-tone drive. We measure the evolution of trajectories of two quantum states, initially prepared at nearby points in synthetic phase space. We detect the synthetic Hall effect through the predicted overlap oscillations at a quantized fundamental frequency proportional to the Chern number, which characterizes the topological phases of the system. We further observe half-quantization of the Chern number at the transition between the synthetic Hall regime and the trivial regime, and the associated concentration of local Berry curvature in synthetic phase space. Our Letter opens up the possibility of using driven qubits to design and study higher-dimensional topological insulators and semimetals in synthetic dimensions.
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Affiliation(s)
- Eric Boyers
- Department of Physics, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, USA
| | - Philip J D Crowley
- Department of Physics, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, USA
| | - Anushya Chandran
- Department of Physics, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, USA
| | - Alexander O Sushkov
- Department of Physics, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, USA
- Department of Electrical and Computer Engineering, Boston University, Boston, Massachusetts 02215, USA
- Photonics Center, Boston University, Boston, Massachusetts 02215, USA
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25
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De Giovannini U, Hübener H, Sato SA, Rubio A. Direct Measurement of Electron-Phonon Coupling with Time-Resolved ARPES. PHYSICAL REVIEW LETTERS 2020; 125:136401. [PMID: 33034494 DOI: 10.1103/physrevlett.125.136401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Accepted: 08/25/2020] [Indexed: 06/11/2023]
Abstract
Time- and angular- resolved photoelectron spectroscopy is a powerful technique to measure electron dynamics in solids. Recent advances in this technique have facilitated band and energy resolved observations of the effect that excited phonons, have on the electronic structure. Here, we show with the help of ab initio simulations that the Fourier analysis of the time-resolved measurements of solids with excited phonon modes enables the determination of the band- and mode-resolved electron-phonon coupling directly from the experimental data without any additional input from theory. Such an observation is not restricted to regions of strong electron-phonon coupling and does not require strongly excited or hot phonons, but can be employed to monitor the dynamical renormalization of phonons in driven phases of matter.
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Affiliation(s)
- Umberto De Giovannini
- Max Planck Institute for the Structure and Dynamics of Matter and Center for Free Electron Laser Science, 22761 Hamburg, Germany
| | - Hannes Hübener
- Max Planck Institute for the Structure and Dynamics of Matter and Center for Free Electron Laser Science, 22761 Hamburg, Germany
| | - Shunsuke A Sato
- Max Planck Institute for the Structure and Dynamics of Matter and Center for Free Electron Laser Science, 22761 Hamburg, Germany
- Center for Computational Sciences, University of Tsukuba, Tsukuba 305-8577, Japan
| | - Angel Rubio
- Max Planck Institute for the Structure and Dynamics of Matter and Center for Free Electron Laser Science, 22761 Hamburg, Germany
- Center for Computational Quantum Physics (CCQ), The Flatiron Institute, 162 Fifth avenue, New York, New York 10010, USA
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26
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Ünzelmann M, Bentmann H, Eck P, Kißlinger T, Geldiyev B, Rieger J, Moser S, Vidal RC, Kißner K, Hammer L, Schneider MA, Fauster T, Sangiovanni G, Di Sante D, Reinert F. Orbital-Driven Rashba Effect in a Binary Honeycomb Monolayer AgTe. PHYSICAL REVIEW LETTERS 2020; 124:176401. [PMID: 32412286 DOI: 10.1103/physrevlett.124.176401] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Accepted: 03/25/2020] [Indexed: 06/11/2023]
Abstract
The Rashba effect is fundamental to the physics of two-dimensional electron systems and underlies a variety of spintronic phenomena. It has been proposed that the formation of Rashba-type spin splittings originates microscopically from the existence of orbital angular momentum (OAM) in the Bloch wave functions. Here, we present detailed experimental evidence for this OAM-based origin of the Rashba effect by angle-resolved photoemission (ARPES) and two-photon photoemission experiments for a monolayer AgTe on Ag(111). Using quantitative low-energy electron diffraction analysis, we determine the structural parameters and the stacking of the honeycomb overlayer with picometer precision. Based on an orbital-symmetry analysis in ARPES and supported by first-principles calculations, we unequivocally relate the presence and absence of Rashba-type spin splittings in different bands of AgTe to the existence of OAM.
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Affiliation(s)
- Maximilian Ünzelmann
- Experimentelle Physik VII and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Hendrik Bentmann
- Experimentelle Physik VII and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Philipp Eck
- Institut für Theoretische Physik und Astrophysik and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, 97074 Würzburg, Germany
| | - Tilman Kißlinger
- Lehrstuhl für Festkörperphysik, Universität Erlangen-Nürnberg, Staudtstraße 7, D-91058 Erlangen, Germany
| | - Begmuhammet Geldiyev
- Lehrstuhl für Festkörperphysik, Universität Erlangen-Nürnberg, Staudtstraße 7, D-91058 Erlangen, Germany
| | - Janek Rieger
- Lehrstuhl für Festkörperphysik, Universität Erlangen-Nürnberg, Staudtstraße 7, D-91058 Erlangen, Germany
| | - Simon Moser
- Experimentelle Physik IV and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Raphael C Vidal
- Experimentelle Physik VII and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Katharina Kißner
- Experimentelle Physik VII and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
| | - Lutz Hammer
- Lehrstuhl für Festkörperphysik, Universität Erlangen-Nürnberg, Staudtstraße 7, D-91058 Erlangen, Germany
| | - M Alexander Schneider
- Lehrstuhl für Festkörperphysik, Universität Erlangen-Nürnberg, Staudtstraße 7, D-91058 Erlangen, Germany
| | - Thomas Fauster
- Lehrstuhl für Festkörperphysik, Universität Erlangen-Nürnberg, Staudtstraße 7, D-91058 Erlangen, Germany
| | - Giorgio Sangiovanni
- Institut für Theoretische Physik und Astrophysik and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, 97074 Würzburg, Germany
| | - Domenico Di Sante
- Institut für Theoretische Physik und Astrophysik and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, 97074 Würzburg, Germany
| | - Friedrich Reinert
- Experimentelle Physik VII and Würzburg-Dresden Cluster of Excellence ct.qmat, Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany
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