1
|
Muñiz Cano B, Ferreiros Y, Pantaleón PA, Dai J, Tallarida M, Figueroa AI, Marinova V, García-Díez K, Mugarza A, Valenzuela SO, Miranda R, Camarero J, Guinea F, Silva-Guillén JA, Valbuena MA. Experimental Demonstration of a Magnetically Induced Warping Transition in a Topological Insulator Mediated by Rare-Earth Surface Dopants. NANO LETTERS 2023. [PMID: 37156508 DOI: 10.1021/acs.nanolett.3c00587] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Magnetic topological insulators constitute a novel class of materials whose topological surface states (TSSs) coexist with long-range ferromagnetic order, eventually breaking time-reversal symmetry. The subsequent bandgap opening is predicted to co-occur with a distortion of the TSS warped shape from hexagonal to trigonal. We demonstrate such a transition by means of angle-resolved photoemission spectroscopy on the magnetically rare-earth (Er and Dy) surface-doped topological insulator Bi2Se2Te. Signatures of the gap opening are also observed. Moreover, increasing the dopant coverage results in a tunable p-type doping of the TSS, thereby allowing for a gradual tuning of the Fermi level toward the magnetically induced bandgap. A theoretical model where a magnetic Zeeman out-of-plane term is introduced in the Hamiltonian governing the TSS rationalizes these experimental results. Our findings offer new strategies to control magnetic interactions with TSSs and open up viable routes for the realization of the quantum anomalous Hall effect.
Collapse
Affiliation(s)
- Beatriz Muñiz Cano
- Instituto Madrileño de Estudios Avanzados, IMDEA Nanociencia, Calle Faraday 9, 28049 Madrid, Spain
| | - Yago Ferreiros
- Instituto Madrileño de Estudios Avanzados, IMDEA Nanociencia, Calle Faraday 9, 28049 Madrid, Spain
| | - Pierre A Pantaleón
- Instituto Madrileño de Estudios Avanzados, IMDEA Nanociencia, Calle Faraday 9, 28049 Madrid, Spain
| | - Ji Dai
- ALBA Synchrotron Light Source, Cerdanyola del Vallès, 08290 Barcelona, Spain
| | - Massimo Tallarida
- ALBA Synchrotron Light Source, Cerdanyola del Vallès, 08290 Barcelona, Spain
| | - Adriana I Figueroa
- Departament de Física de la Matéria Condensada, Universitat de Barcelona, 08028 Barcelona, Spain
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, 08193 Barcelona, Spain
| | - Vera Marinova
- Institute of Optical Materials and Technologies, Bulgarian Academy of Sciences, Acad. G. Bontchev, Str. 109, 1113 Sofia, Bulgaria
| | - Kevin García-Díez
- ALBA Synchrotron Light Source, Cerdanyola del Vallès, 08290 Barcelona, Spain
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, 08193 Barcelona, Spain
| | - Aitor Mugarza
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, 08193 Barcelona, Spain
- ICREA Institució Catalana de Recerca i Estudis Avançats, Lluis Companys 23, 08010 Barcelona, Spain
| | - Sergio O Valenzuela
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, 08193 Barcelona, Spain
- ICREA Institució Catalana de Recerca i Estudis Avançats, Lluis Companys 23, 08010 Barcelona, Spain
| | - Rodolfo Miranda
- Instituto Madrileño de Estudios Avanzados, IMDEA Nanociencia, Calle Faraday 9, 28049 Madrid, Spain
- Departamento de Física de la Materia Condensada, Instituto "Nicolás Cabrera" and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid (UAM), Campus de Cantoblanco, 28049 Madrid, Spain
| | - Julio Camarero
- Instituto Madrileño de Estudios Avanzados, IMDEA Nanociencia, Calle Faraday 9, 28049 Madrid, Spain
- Departamento de Física de la Materia Condensada, Instituto "Nicolás Cabrera" and Condensed Matter Physics Center (IFIMAC), Universidad Autónoma de Madrid (UAM), Campus de Cantoblanco, 28049 Madrid, Spain
| | - Francisco Guinea
- Instituto Madrileño de Estudios Avanzados, IMDEA Nanociencia, Calle Faraday 9, 28049 Madrid, Spain
- Donostia International Physics Center, Paseo Manuel de Lardizábal 4, 20018 San Sebastián, Spain
- Ikerbasque, Basque Foundation for Science, 48009 Bilbao, Spain
| | - Jose Angel Silva-Guillén
- Instituto Madrileño de Estudios Avanzados, IMDEA Nanociencia, Calle Faraday 9, 28049 Madrid, Spain
| | - Miguel A Valbuena
- Instituto Madrileño de Estudios Avanzados, IMDEA Nanociencia, Calle Faraday 9, 28049 Madrid, Spain
| |
Collapse
|
2
|
Ptok A, Kapcia KJ, Ciechan A. Electronic properties of Bi 2Se 3 dopped by 3d transition metal (Mn, Fe, Co, or Ni) ions. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:065501. [PMID: 32957088 DOI: 10.1088/1361-648x/abba6a] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Topological insulators are characterized by the existence of band inversion and the possibility of the realization of surface states. Doping with a magnetic atom, which is a source of the time-reversal symmetry breaking, can lead to realization of novel magneto-electronic properties of the system. In this paper, we study effects of substitution by the transition metal ions (Mn, Fe, Co and Ni) into Bi2Se3 on its electric properties. Using the ab inito supercell technique, we investigate the density of states and the projected band structure. Under such substitution the shift of the Fermi level is observed. We find the existence of nearly dispersionless bands around the Fermi level associated with substituted atoms, especially, in the case of the Co and Ni. Additionally, we discuss the modification of the electron localization function as well as charge and spin redistribution in the system. Our study shows a strong influence of the transition metal-Se bond on local modifications of the physical properties. The results are also discussed in the context of the interplay between energy levels of the magnetic impurities and topological surface states.
Collapse
Affiliation(s)
- Andrzej Ptok
- Institute of Nuclear Physics, Polish Academy of Sciences, ul. W. E. Radzikowskiego 152, PL-31342 Kraków, Poland
| | - Konrad Jerzy Kapcia
- Institute of Nuclear Physics, Polish Academy of Sciences, ul. W. E. Radzikowskiego 152, PL-31342 Kraków, Poland
| | - Anna Ciechan
- Institute of Physics, Polish Academy of Sciences, al. Lotników 32/46, PL-02668 Warsaw, Poland
| |
Collapse
|
3
|
Desvignes L, Stolyarov VS, Aprili M, Massee F. Tunable High Speed Atomic Rotor in Bi 2Se 3 Revealed by Current Noise. ACS NANO 2021; 15:1421-1425. [PMID: 33444496 DOI: 10.1021/acsnano.0c08718] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The ability to manipulate individual atoms and molecules using a scanning tunneling microscope (STM) has been crucial for the development of a vast array of atomic-scale devices and structures ranging from nanoscale motors and switches to quantum corrals. Molecular motors in particular have attracted considerable attention in view of their potential for assembly into complex nanoscale machines. Whereas the manipulated atoms or molecules are usually on top of a substrate, motors embedded in a lattice can be very beneficial for bottom-up construction, and may additionally be used to probe the influence of the lattice on the electronic properties of the host material. Here, we present the discovery of controlled manipulation of a rotor in Fe doped Bi2Se3. We find that the current into the rotor, which can be finely tuned with the voltage, drives omni-directional switching between three equivalent orientations, each of which can be frozen in at small bias voltage. Using current fluctuation measurements at 1 MHz and model simulations, we estimate that switching rates of hundreds of kHz for sub-nanoampere currents are achieved.
Collapse
Affiliation(s)
- Léonard Desvignes
- Université Paris-Saclay, CNRS, Laboratoire de Physique des Solides, 91405, Orsay, France
| | | | - Marco Aprili
- Université Paris-Saclay, CNRS, Laboratoire de Physique des Solides, 91405, Orsay, France
| | - Freek Massee
- Université Paris-Saclay, CNRS, Laboratoire de Physique des Solides, 91405, Orsay, France
| |
Collapse
|
4
|
Cuxart MG, Valbuena MA, Robles R, Moreno C, Bonell F, Sauthier G, Imaz I, Xu H, Nistor C, Barla A, Gargiani P, Valvidares M, Maspoch D, Gambardella P, Valenzuela SO, Mugarza A. Molecular Approach for Engineering Interfacial Interactions in Magnetic/Topological Insulator Heterostructures. ACS NANO 2020; 14:6285-6294. [PMID: 32293865 DOI: 10.1021/acsnano.0c02498] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Controlling interfacial interactions in magnetic/topological insulator heterostructures is a major challenge for the emergence of novel spin-dependent electronic phenomena. As for any rational design of heterostructures that rely on proximity effects, one should ideally retain the overall properties of each component while tuning interactions at the interface. However, in most inorganic interfaces, interactions are too strong, consequently perturbing, and even quenching, both the magnetic moment and the topological surface states at each side of the interface. Here, we show that these properties can be preserved using ligand chemistry to tune the interaction of magnetic ions with the surface states. By depositing Co-based porphyrin and phthalocyanine monolayers on the surface of Bi2Te3 thin films, robust interfaces are formed that preserve undoped topological surface states as well as the pristine magnetic moment of the divalent Co ions. The selected ligands allow us to tune the interfacial hybridization within this weak interaction regime. These results, which are in stark contrast with the observed suppression of the surface state at the first quintuple layer of Bi2Se3 induced by the interaction with Co phthalocyanines, demonstrate the capability of planar metal-organic molecules to span interactions from the strong to the weak limit.
Collapse
Affiliation(s)
- Marc G Cuxart
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, 08193 Barcelona, Spain
| | - Miguel Angel Valbuena
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, 08193 Barcelona, Spain
| | - Roberto Robles
- Centro de Fı́sica de Materiales CFM/MPC (CSIC-UPV/EHU), 20018 Donostia-San Sebastián Spain
| | - César Moreno
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, 08193 Barcelona, Spain
| | - Frédéric Bonell
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, 08193 Barcelona, Spain
| | - Guillaume Sauthier
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, 08193 Barcelona, Spain
| | - Inhar Imaz
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, 08193 Barcelona, Spain
| | - Heng Xu
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, 08193 Barcelona, Spain
| | - Corneliu Nistor
- Department of Materials, ETH Zurich, Hönggerbergring 64, CH-8093 Zurich, Switzerland
| | - Alessandro Barla
- Istituto di Struttura della Materia (ISM), Consiglio Nazionale delle Ricerche (CNR), I-34149 Trieste, Italy
| | - Pierluigi Gargiani
- ALBA Synchrotron Light Source, Carretera BP 1413km 3.3, E-08290 Cerdanyola del Vallès, Spain
| | - Manuel Valvidares
- ALBA Synchrotron Light Source, Carretera BP 1413km 3.3, E-08290 Cerdanyola del Vallès, Spain
| | - Daniel Maspoch
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, 08193 Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), 08070 Barcelona, Spain
| | - Pietro Gambardella
- Department of Materials, ETH Zurich, Hönggerbergring 64, CH-8093 Zurich, Switzerland
| | - Sergio O Valenzuela
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, 08193 Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), 08070 Barcelona, Spain
| | - Aitor Mugarza
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and BIST, Campus UAB, 08193 Barcelona, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), 08070 Barcelona, Spain
| |
Collapse
|
5
|
Yu L, Hu L, Barreda JL, Guan T, He X, Wu K, Li Y, Xiong P. Robust Gapless Surface State against Surface Magnetic Impurities on (Bi_{0.5}Sb_{0.5})_{2}Te_{3} Evidenced by In Situ Magnetotransport Measurements. PHYSICAL REVIEW LETTERS 2020; 124:126601. [PMID: 32281842 DOI: 10.1103/physrevlett.124.126601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 02/28/2020] [Indexed: 06/11/2023]
Abstract
Despite extensive experimental and theoretical efforts, the important issue of the effects of surface magnetic impurities on the topological surface state of a topological insulator (TI) remains unresolved. We elucidate the effects of Cr impurities on epitaxial thin films of (Bi_{0.5}Sb_{0.5})_{2}Te_{3}: Cr adatoms are incrementally deposited onto the TI held in ultrahigh vacuum at low temperatures, and in situ magnetoconductivity and Hall effect measurements are performed at each increment with electrostatic gating. In the experimentally identified surface transport regime, the measured minimum electron density shows a nonmonotonic evolution with the Cr density (n_{Cr}): it first increases and then decreases with n_{Cr}. This unusual behavior is ascribed to the dual roles of the Cr as ionized impurities and electron donors, having competing effects of enhancing and decreasing the electronic inhomogeneities in the surface state at low and high n_{Cr}, respectively. The magnetoconductivity is obtained for different n_{Cr} on one and the same sample, which yields clear evidence that the weak antilocalization effect persists and the surface state remains gapless up to the highest n_{Cr}, contrary to the expectation that the deposited Cr should break the time-reversal symmetry and induce a gap opening at the Dirac point.
Collapse
Affiliation(s)
- Liuqi Yu
- Department of Physics, Florida State University, Tallahassee, Florida 32306, USA
| | - Longqian Hu
- Department of Physics, Florida State University, Tallahassee, Florida 32306, USA
| | - Jorge L Barreda
- Department of Physics, Florida State University, Tallahassee, Florida 32306, USA
| | - Tong Guan
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Xiaoyue He
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Kehui Wu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
| | - Yongqing Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
| | - Peng Xiong
- Department of Physics, Florida State University, Tallahassee, Florida 32306, USA
| |
Collapse
|
6
|
Xue W, Li J, Peng X, He C, Ouyang T, Zhang C, Tang C, Li Z, Liu H, Zhong J. First principles study of semihydrogenated graphene and topological insulator heterojunction. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2019; 31:365002. [PMID: 31100737 DOI: 10.1088/1361-648x/ab228a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Based on first principles calculations, we study the electronic properties of heterostructures formed by a 2D ferromagnetic insulator semihydrogenated graphene (SG) and topological insulator Bi2Se3 thin films of a few quintuple layers (QLs). It is found that the unsaturated C atoms in SG form bonds with Se atoms in Bi2Se3 thin film and the top surface states (at the interface) are strongly hybridized with SG. Due to breaking of time-reversal symmetry, the surface states open gaps of 40 meV and 150 meV for SG/3QL-Bi2Se3 and SG/5QL-Bi2Se3 heterostructures, respectively. Furthermore, a giant Rashba spin splitting is found induced by the SG layer.
Collapse
Affiliation(s)
- Wenming Xue
- Hunan Key Laboratory of Micro-Nano Energy Materials and Devices, Xiangtan University, Hunan 411105, People's Republic of China. School of Physics and Optoelectronics Engineering, Xiangtan University, Hunan 411105, People's Republic of China
| | | | | | | | | | | | | | | | | | | |
Collapse
|
7
|
Tkáč V, Výborný K, Komanický V, Warmuth J, Michiardi M, Ngankeu AS, Vondráček M, Tarasenko R, Vališka M, Stetsovych V, Carva K, Garate I, Bianchi M, Wiebe J, Holý V, Hofmann P, Springholz G, Sechovský V, Honolka J. Influence of an Anomalous Temperature Dependence of the Phase Coherence Length on the Conductivity of Magnetic Topological Insulators. PHYSICAL REVIEW LETTERS 2019; 123:036406. [PMID: 31386447 DOI: 10.1103/physrevlett.123.036406] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2018] [Revised: 05/08/2019] [Indexed: 06/10/2023]
Abstract
Magnetotransport constitutes a useful probe to understand the interplay between electronic band topology and magnetism in spintronic devices. A recent theory of Lu and Shen [Phys. Rev. Lett. 112, 146601 (2014)PRLTAO0031-900710.1103/PhysRevLett.112.146601] on magnetically doped topological insulators predicts that quantum corrections Δκ to the temperature dependence of conductivity can change sign across the Curie transition. This phenomenon has been attributed to a suppression of the Berry phase of the topological surface states at the Fermi level, caused by a magnetic energy gap. Here, we demonstrate experimentally that Δκ can reverse its sign even when the Berry phase at the Fermi level remains unchanged. The contradictory behavior to theory predictions is resolved by extending the model by Lu and Shen to a nonmonotonic temperature scaling of the inelastic scattering length showing a turning point at the Curie transition.
Collapse
Affiliation(s)
- V Tkáč
- Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University, Ke Karlovu 5, CZ-12116 Prague 2, Czech Republic
- Institute of Physics, P. J. Šafárik University, Park Angelinum 9, 040 01 Košice, Slovak Republic
| | - K Výborný
- Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, CZ-16253 Praha 6, Czech Republic
| | - V Komanický
- Institute of Physics, P. J. Šafárik University, Park Angelinum 9, 040 01 Košice, Slovak Republic
| | - J Warmuth
- Department of Physics, University of Hamburg, D-20355 Hamburg, Germany
| | - M Michiardi
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center (iNANO), University of Aarhus, 8000 Aarhus C, Denmark
| | - A S Ngankeu
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center (iNANO), University of Aarhus, 8000 Aarhus C, Denmark
| | - M Vondráček
- Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, CZ-18221 Prague 8, Czech Republic
| | - R Tarasenko
- Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University, Ke Karlovu 5, CZ-12116 Prague 2, Czech Republic
- Institute of Physics, P. J. Šafárik University, Park Angelinum 9, 040 01 Košice, Slovak Republic
| | - M Vališka
- Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University, Ke Karlovu 5, CZ-12116 Prague 2, Czech Republic
| | - V Stetsovych
- Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, CZ-18221 Prague 8, Czech Republic
| | - K Carva
- Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University, Ke Karlovu 5, CZ-12116 Prague 2, Czech Republic
| | - I Garate
- Département de physique and Institut quantique, Université de Sherbrooke, Sherbrooke (Québec), Canada J1K 2R1
| | - M Bianchi
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center (iNANO), University of Aarhus, 8000 Aarhus C, Denmark
| | - J Wiebe
- Department of Physics, University of Hamburg, D-20355 Hamburg, Germany
| | - V Holý
- Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University, Ke Karlovu 5, CZ-12116 Prague 2, Czech Republic
| | - Ph Hofmann
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center (iNANO), University of Aarhus, 8000 Aarhus C, Denmark
| | - G Springholz
- Institute of Semiconductor and Solid State Physics, Johannes Kepler University, Altenbergerstrasse 69, A-4040 Linz, Austria
| | - V Sechovský
- Department of Condensed Matter Physics, Faculty of Mathematics and Physics, Charles University, Ke Karlovu 5, CZ-12116 Prague 2, Czech Republic
| | - J Honolka
- Institute of Physics, Academy of Sciences of the Czech Republic, Na Slovance 2, CZ-18221 Prague 8, Czech Republic
| |
Collapse
|
8
|
Pia AD, Lisi S, Luca OD, Warr DA, Lawrence J, Otrokov MM, Aliev ZS, Chulkov EV, Agostino RG, Arnau A, Papagno M, Costantini G. TCNQ Physisorption on the Topological Insulator Bi 2 Se 3. Chemphyschem 2018; 19:2405-2410. [PMID: 29847012 DOI: 10.1002/cphc.201800259] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2018] [Indexed: 11/07/2022]
Abstract
Topological insulators are promising candidates for spintronic applications due to their topologically protected, spin-momentum locked and gapless surface states. The breaking of the time-reversal symmetry after the introduction of magnetic impurities, such as 3d transition metal atoms embedded in two-dimensional molecular networks, could lead to several phenomena interesting for device fabrication. The first step towards the fabrication of metal-organic coordination networks on the surface of a topological insulator is to investigate the adsorption of the pure molecular layer, which is the aim of this study. Here, the effect of the deposition of the electron acceptor 7,7,8,8-tetracyanoquinodimethane (TCNQ) molecules on the surface of a prototypical topological insulator, bismuth selenide (Bi2 Se3 ), is investigated. Scanning tunneling microscope images at low-temperature reveal the formation of a highly ordered two-dimensional molecular network. The essentially unperturbed electronic structure of the topological insulator observed by photoemission spectroscopy measurements demonstrates a negligible charge transfer between the molecular layer and the substrate. Density functional theory calculations confirm the picture of a weakly interacting adsorbed molecular layer. These results reveal significant potential of TCNQ for the realization of metal-organic coordination networks on the topological insulator surface.
Collapse
Affiliation(s)
- Ada Della Pia
- Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK
| | - Simone Lisi
- Institut Néel, 25 Rue des Martyrs BP 166, 38042, Grenoble, France
| | - Oreste De Luca
- Dipartimento di Fisica, Università della Calabria, 87036, Arcavacata di Rende (CS), Italy
| | - Daniel A Warr
- Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK
| | - J Lawrence
- Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK
| | - Mikhail M Otrokov
- Departamento de Física de Materiales UPV/EHU, Centro de Física de Materiales CFM-MPC and Centro Mixto CSIC-UPV/EHU, 20080, San Sebastián/Donostia, Spain
- Saint Petersburg State University, 198504, Saint Petersburg, Russia
- Tomsk State University, 634050, Tomsk, Russia
| | - Ziya S Aliev
- Azerbaijan State Oil and Industry University, AZ1010, Baku, Azerbaijan
- Materials Science and Nanotechnology Department, Near East University, North Cyprus, Mersin 10, 99138, Nicosia, Turkey
| | - Evgueni V Chulkov
- Departamento de Física de Materiales UPV/EHU, Centro de Física de Materiales CFM-MPC and Centro Mixto CSIC-UPV/EHU, 20080, San Sebastián/Donostia, Spain
- Saint Petersburg State University, 198504, Saint Petersburg, Russia
- Donostia International Physics Center (DIPC), 20018, Donostia-San Sebastian, Spain
| | - Raffaele G Agostino
- Dipartimento di Fisica, Università della Calabria, 87036, Arcavacata di Rende (CS), Italy
| | - Andrés Arnau
- Departamento de Física de Materiales UPV/EHU, Centro de Física de Materiales CFM-MPC and Centro Mixto CSIC-UPV/EHU, 20080, San Sebastián/Donostia, Spain
- Donostia International Physics Center (DIPC), 20018, Donostia-San Sebastian, Spain
| | - Marco Papagno
- Dipartimento di Fisica, Università della Calabria, 87036, Arcavacata di Rende (CS), Italy
| | - Giovanni Costantini
- Department of Chemistry, University of Warwick, Gibbet Hill Road, Coventry CV4 7AL, UK
| |
Collapse
|
9
|
Shao B, Schüler M, Schönhoff G, Frauenheim T, Czycholl G, Wehling TO. Optically and Electrically Controllable Adatom Spin-orbital Dynamics in Transition Metal Dichalcogenides. NANO LETTERS 2017; 17:6721-6726. [PMID: 28978200 DOI: 10.1021/acs.nanolett.7b02785] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We analyze the interplay of spin-valley coupling, orbital physics, and magnetic anisotropy taking place at single magnetic atoms adsorbed on semiconducting transition metal dichalcogenides, MX2 (M = Mo, W; X = S, Se). Orbital selection rules turn out to govern the kinetic exchange coupling between the adatom and charge carriers in the MX2 and lead to highly orbitally dependent spin-flip scattering rates, as we illustrate for the example of transition metal adatoms with d9 configuration. Our ab initio calculations suggest that d9 configurations are realizable by single Co, Rh, or Ir adatoms on MoS2, which additionally exhibit a sizable magnetic anisotropy. We find that the interaction of the adatom with carriers in the MX2 allows to tune its behavior from a quantum regime with full Kondo screening to a regime of "Ising spintronics" where its spin-orbital moment acts as classical bit, which can be erased and written electronically and optically.
Collapse
Affiliation(s)
- Bin Shao
- Bremen Center for Computational Materials Science and ‡Institut für Theoretische Physik, Universität Bremen , 28359 Bremen, Germany
| | - Malte Schüler
- Bremen Center for Computational Materials Science and ‡Institut für Theoretische Physik, Universität Bremen , 28359 Bremen, Germany
| | - Gunnar Schönhoff
- Bremen Center for Computational Materials Science and ‡Institut für Theoretische Physik, Universität Bremen , 28359 Bremen, Germany
| | - Thomas Frauenheim
- Bremen Center for Computational Materials Science and ‡Institut für Theoretische Physik, Universität Bremen , 28359 Bremen, Germany
| | - Gerd Czycholl
- Bremen Center for Computational Materials Science and ‡Institut für Theoretische Physik, Universität Bremen , 28359 Bremen, Germany
| | - Tim O Wehling
- Bremen Center for Computational Materials Science and ‡Institut für Theoretische Physik, Universität Bremen , 28359 Bremen, Germany
| |
Collapse
|
10
|
Kim J, Kim KW, Wang H, Sinova J, Wu R. Understanding the Giant Enhancement of Exchange Interaction in Bi_{2}Se_{3}-EuS Heterostructures. PHYSICAL REVIEW LETTERS 2017; 119:027201. [PMID: 28753347 DOI: 10.1103/physrevlett.119.027201] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Indexed: 06/07/2023]
Abstract
A recent experiment indicated that a ferromagnetic EuS film in contact with a topological insulator Bi_{2}Se_{3} might show a largely enhanced Curie temperature and perpendicular magnetic anisotropy [F. Katmis et al., Nature (London) 533, 513 (2016).NATUAS0028-083610.1038/nature17635]. Through systematic density functional calculations, we demonstrate that in addition to the factor that Bi_{2}Se_{3} has a strong spin orbit coupling, the topological surface states are crucial to make these unusual behaviors robust as they hybridize with EuS states and extend rather far into the magnetic layers. The magnetic moments of Eu atoms are nevertheless not much enhanced, unlike what was reported in the experiment. Our results and model analyses provide useful insights for how these quantities are linked, and pave a way for the control of properties of magnetic films via contact with topological insulators.
Collapse
Affiliation(s)
- Jeongwoo Kim
- Department of Physics and Astronomy, University of California, Irvine, California 92697, USA
| | - Kyoung-Whan Kim
- Institut für Physik, Johannes Gutenberg Universität Mainz, Mainz, 55128, Germany
| | - Hui Wang
- Department of Physics and Astronomy, University of California, Irvine, California 92697, USA
| | - Jairo Sinova
- Institut für Physik, Johannes Gutenberg Universität Mainz, Mainz, 55128, Germany
- Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, 162 53 Praha 6, Czech Republic
| | - Ruqian Wu
- Department of Physics and Astronomy, University of California, Irvine, California 92697, USA
| |
Collapse
|
11
|
Martínez-Velarte MC, Kretz B, Moro-Lagares M, Aguirre MH, Riedemann TM, Lograsso TA, Morellón L, Ibarra MR, Garcia-Lekue A, Serrate D. Chemical Disorder in Topological Insulators: A Route to Magnetism Tolerant Topological Surface States. NANO LETTERS 2017; 17:4047-4054. [PMID: 28605918 DOI: 10.1021/acs.nanolett.7b00311] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We show that the chemical inhomogeneity in ternary three-dimensional topological insulators preserves the topological spin texture of their surface states against a net surface magnetization. The spin texture is that of a Dirac cone with helical spin structure in the reciprocal space, which gives rise to spin-polarized and dissipation-less charge currents. Thanks to the nontrivial topology of the bulk electronic structure, this spin texture is robust against most types of surface defects. However, magnetic perturbations break the time-reversal symmetry, enabling magnetic scattering and loss of spin coherence of the charge carriers. This intrinsic incompatibility precludes the design of magnetoelectronic devices based on the coupling between magnetic materials and topological surface states. We demonstrate that the magnetization coming from individual Co atoms deposited on the surface can disrupt the spin coherence of the carriers in the archetypal topological insulator Bi2Te3, while in Bi2Se2Te the spin texture remains unperturbed. This is concluded from the observation of elastic backscattering events in quasiparticle interference patterns obtained by scanning tunneling spectroscopy. The mechanism responsible for the protection is investigated by energy resolved spectroscopy and ab initio calculations, and it is ascribed to the distorted adsorption geometry of localized magnetic moments due to Se-Te disorder, which suppresses the Co hybridization with the surface states.
Collapse
Affiliation(s)
- M Carmen Martínez-Velarte
- Instituto de Nanociencia de Aragón (INA) & Laboratorio de Microscopias Avanzadas (LMA), University of Zaragoza , 50018 Zaragoza, Spain
- Department of Condensed Matter Physics, University of Zaragoza , 50009 Zaragoza, Spain
- Fundación Instituto de Nanociencia de Aragón (FINA) , 50018 Zaragoza, Spain
| | - Bernhard Kretz
- Donostia International Physics Center (DIPC) , E-20018 San Sebastián, Spain
| | - María Moro-Lagares
- Instituto de Nanociencia de Aragón (INA) & Laboratorio de Microscopias Avanzadas (LMA), University of Zaragoza , 50018 Zaragoza, Spain
- Department of Condensed Matter Physics, University of Zaragoza , 50009 Zaragoza, Spain
| | - Myriam H Aguirre
- Instituto de Nanociencia de Aragón (INA) & Laboratorio de Microscopias Avanzadas (LMA), University of Zaragoza , 50018 Zaragoza, Spain
- Department of Condensed Matter Physics, University of Zaragoza , 50009 Zaragoza, Spain
- Fundación Instituto de Nanociencia de Aragón (FINA) , 50018 Zaragoza, Spain
| | - Trevor M Riedemann
- Ames Laboratory , U.S. Department of Energy, Ames, Iowa 50011, United States
| | - Thomas A Lograsso
- Ames Laboratory , U.S. Department of Energy, Ames, Iowa 50011, United States
- Department of Materials Sciences & Engineering, Iowa State University , Ames, Iowa 50011 United States
| | - Luis Morellón
- Instituto de Nanociencia de Aragón (INA) & Laboratorio de Microscopias Avanzadas (LMA), University of Zaragoza , 50018 Zaragoza, Spain
- Department of Condensed Matter Physics, University of Zaragoza , 50009 Zaragoza, Spain
- Fundación Instituto de Nanociencia de Aragón (FINA) , 50018 Zaragoza, Spain
| | - M Ricardo Ibarra
- Instituto de Nanociencia de Aragón (INA) & Laboratorio de Microscopias Avanzadas (LMA), University of Zaragoza , 50018 Zaragoza, Spain
- Department of Condensed Matter Physics, University of Zaragoza , 50009 Zaragoza, Spain
- Fundación Instituto de Nanociencia de Aragón (FINA) , 50018 Zaragoza, Spain
| | - Arán Garcia-Lekue
- Donostia International Physics Center (DIPC) , E-20018 San Sebastián, Spain
- IKERBASQUE, Basque Foundation for Science , E-48011 Bilbao, Spain
| | - David Serrate
- Instituto de Nanociencia de Aragón (INA) & Laboratorio de Microscopias Avanzadas (LMA), University of Zaragoza , 50018 Zaragoza, Spain
- Department of Condensed Matter Physics, University of Zaragoza , 50009 Zaragoza, Spain
- Fundación Instituto de Nanociencia de Aragón (FINA) , 50018 Zaragoza, Spain
| |
Collapse
|
12
|
Zhong M, Li S, Duan HJ, Hu LB, Yang M, Wang RQ. Effect of impurity resonant states on optical and thermoelectric properties on the surface of a topological insulator. Sci Rep 2017. [PMID: 28638115 PMCID: PMC5479872 DOI: 10.1038/s41598-017-04360-x] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
We investigate the thermoelectric effect on a topological insulator surface with particular interest in impurity-induced resonant states. To clarify the role of the resonant states, we calculate the dc and ac conductivities and the thermoelectric coefficients along the longitudinal direction within the full Born approximation. It is found that at low temperatures, the impurity resonant state with strong energy de-pendence can lead to a zero-energy peak in the dc conductivity, whose height is sensitively dependent on the strength of scattering potential, and even can reverse the sign of the thermopower, implying the switching from n- to p-type carriers. Also, we exhibit the thermoelectric signatures for the filling process of a magnetic band gap by the resonant state. We further study the impurity effect on the dynamic optical conductivity, and find that the resonant state also generates an optical conductivity peak at the absorption edge for the interband transition. These results provide new perspectives for understanding the doping effect on topological insulator materials.
Collapse
Affiliation(s)
- Min Zhong
- Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou, 510006, China
| | - Shuai Li
- Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou, 510006, China
| | - Hou-Jian Duan
- Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou, 510006, China
| | - Liang-Bin Hu
- Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou, 510006, China
| | - Mou Yang
- Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou, 510006, China
| | - Rui-Qiang Wang
- Guangdong Provincial Key Laboratory of Quantum Engineering and Quantum Materials, School of Physics and Telecommunication Engineering, South China Normal University, Guangzhou, 510006, China.
| |
Collapse
|
13
|
Sánchez-Barriga J, Ogorodnikov II, Kuznetsov MV, Volykhov AA, Matsui F, Callaert C, Hadermann J, Verbitskiy NI, Koch RJ, Varykhalov A, Rader O, Yashina LV. Observation of hidden atomic order at the interface between Fe and topological insulator Bi2Te3. Phys Chem Chem Phys 2017; 19:30520-30532. [DOI: 10.1039/c7cp04875k] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
The first compelling evidence of unique atomic order at the ferromagnet Fe/topological insulator Bi2Te3 interface.
Collapse
Affiliation(s)
| | - Ilya I. Ogorodnikov
- Institute of Solid State Chemistry of the Ural Branch of the Russian Academy of Sciences
- 620990 Ekaterinburg
- Russia
| | - Mikhail V. Kuznetsov
- Institute of Solid State Chemistry of the Ural Branch of the Russian Academy of Sciences
- 620990 Ekaterinburg
- Russia
| | - Andrey A. Volykhov
- Department of Chemistry, Lomonosov Moscow State University
- 119991 Moscow
- Russia
- Kurnakov Institute of General and Inorganic Chemistry RAS
- 119991 Moscow
| | | | | | - Joke Hadermann
- EMAT, Department of Physics
- University of Antwerp
- 2020 Antwerp
- Belgium
| | | | - Roland J. Koch
- Advanced Light Source, Lawrence Berkeley National Laboratory
- Berkeley
- USA
| | - Andrei Varykhalov
- Helmholtz-Zentrum Berlin für Materialien und Energie
- 12489 Berlin
- Germany
| | - Oliver Rader
- Helmholtz-Zentrum Berlin für Materialien und Energie
- 12489 Berlin
- Germany
| | - Lada V. Yashina
- Department of Chemistry, Lomonosov Moscow State University
- 119991 Moscow
- Russia
| |
Collapse
|
14
|
Paaske J, Gaidamauskas E. Tunable Magnetic Anisotropy from Higher-Harmonics Exchange Scattering on the Surface of a Topological Insulator. PHYSICAL REVIEW LETTERS 2016; 117:177201. [PMID: 27824441 DOI: 10.1103/physrevlett.117.177201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Indexed: 06/06/2023]
Abstract
We show that higher-harmonics exchange scattering from a magnetic adatom on the surface of a three dimensional topological insulator leads to a magnetic anisotropy whose magnitude and sign may be tuned by adjusting the chemical potential of the helical surface band. As the chemical potential moves from the Dirac point towards the surface band edge, the surface normal is found to change from a magnetic easy to a hard axis. Hexagonal warping is shown to diminish the region with easy axis anisotropy, and to suppress the anisotropy altogether. This indirect contribution can be comparable in magnitude to the intrinsic term arising from crystal field splitting and atomic spin-orbit coupling, and its tunability with the chemical potential makes the two contributions experimentally discernible, and endows this source of anisotropy with potentially interesting magnetic functionality.
Collapse
Affiliation(s)
- Jens Paaske
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark
| | - Erikas Gaidamauskas
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark
| |
Collapse
|
15
|
Ibañez-Azpiroz J, Dos Santos Dias M, Blügel S, Lounis S. Zero-Point Spin-Fluctuations of Single Adatoms. NANO LETTERS 2016; 16:4305-4311. [PMID: 27248465 DOI: 10.1021/acs.nanolett.6b01344] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Stabilizing the magnetic signal of single adatoms is a crucial step toward their successful usage in widespread technological applications such as high-density magnetic data storage devices. The quantum mechanical nature of these tiny objects, however, introduces intrinsic zero-point spin-fluctuations that tend to destabilize the local magnetic moment of interest by dwindling the magnetic anisotropy potential barrier even at absolute zero temperature. Here, we elucidate the origins and quantify the effect of the fundamental ingredients determining the magnitude of the fluctuations, namely, the (i) local magnetic moment, (ii) spin-orbit coupling, and (iii) electron-hole Stoner excitations. Based on a systematic first-principles study of 3d and 4d adatoms, we demonstrate that the transverse contribution of the fluctuations is comparable in size to the magnetic moment itself, leading to a remarkable ≳50% reduction of the magnetic anisotropy energy. Our analysis gives rise to a comprehensible diagram relating the fluctuation magnitude to characteristic features of adatoms, providing practical guidelines for designing magnetically stable nanomagnets with minimal quantum fluctuations.
Collapse
Affiliation(s)
- Julen Ibañez-Azpiroz
- Peter Grünberg Institute and Institute for Advanced Simulation, Forschungszentrum Jülich & JARA, D-52425 Jülich, Germany
| | - Manuel Dos Santos Dias
- Peter Grünberg Institute and Institute for Advanced Simulation, Forschungszentrum Jülich & JARA, D-52425 Jülich, Germany
| | - Stefan Blügel
- Peter Grünberg Institute and Institute for Advanced Simulation, Forschungszentrum Jülich & JARA, D-52425 Jülich, Germany
| | - Samir Lounis
- Peter Grünberg Institute and Institute for Advanced Simulation, Forschungszentrum Jülich & JARA, D-52425 Jülich, Germany
| |
Collapse
|
16
|
Zhang W, Hajiheidari F, Li Y, Mazzarello R. Electronic and magnetic properties of H-terminated graphene nanoribbons deposited on the topological insulator Sb2Te3. Sci Rep 2016; 6:29009. [PMID: 27405058 PMCID: PMC4941537 DOI: 10.1038/srep29009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2016] [Accepted: 06/09/2016] [Indexed: 11/09/2022] Open
Abstract
Magnetism in zigzag graphene nanoribbons (GNRs) has received enormous attention recently, due to the one-dimensional nature of this phenomenon, as well as its potential applications in the field of spintronics. In this work, we present a density functional theory (DFT) investigation of H-passivated GNRs on the (111) surface of the topological insulator Sb2Te3. We show that the chemical interaction between the GNR and the substrate is weak. As a result, the GNR-surface distance is large, of the order of 3.4 Angstrom, doping effects are almost negligible, and the mean-field magnetic properties of the GNR are preserved. Nevertheless, the presence of the substrate affects significantly the magnitude of the exchange coupling constants between the edges. Although our DFT calculations do not properly describe quantum fluctuations that destabilize the edge magnetism in free-standing GNRs, they provide important information about the stabilizing mechanisms which originate from the substrate-induced spin orbit coupling and the decoherence effects due to the surface states of Sb2Te3. We argue that, owing to these mechanisms, Sb2Te3 may be a suitable substrate to investigate experimentally the transition from "quantum" to "classical" magnetism in GNRs.
Collapse
Affiliation(s)
- Wei Zhang
- Center for Advancing Materials Performance from the Nanoscale, State Key Laboratory for Mechanical Behavior of Materials, Xi'an Jiaotong University, Xi'an 710049, P.R. China.,Institute for Theoretical Solid State Physics, RWTH Aachen University, D-52074 Aachen, Germany
| | - Farideh Hajiheidari
- Institute for Theoretical Solid State Physics, RWTH Aachen University, D-52074 Aachen, Germany
| | - Yan Li
- Institute for Theoretical Solid State Physics, RWTH Aachen University, D-52074 Aachen, Germany.,Institute of Energy and Climate Research (IEK-6), Forschungszentrum Jülich, D-52425 Jülich, Germany
| | - Riccardo Mazzarello
- Institute for Theoretical Solid State Physics, RWTH Aachen University, D-52074 Aachen, Germany.,JARA-FIT and JARA-HPC, RWTH Aachen University, D-52074 Aachen, Germany
| |
Collapse
|
17
|
Caputo M, Panighel M, Lisi S, Khalil L, Santo GD, Papalazarou E, Hruban A, Konczykowski M, Krusin-Elbaum L, Aliev ZS, Babanly MB, Otrokov MM, Politano A, Chulkov EV, Arnau A, Marinova V, Das PK, Fujii J, Vobornik I, Perfetti L, Mugarza A, Goldoni A, Marsi M. Manipulating the Topological Interface by Molecular Adsorbates: Adsorption of Co-Phthalocyanine on Bi2Se3. NANO LETTERS 2016; 16:3409-3414. [PMID: 27010705 DOI: 10.1021/acs.nanolett.5b02635] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Topological insulators are a promising class of materials for applications in the field of spintronics. New perspectives in this field can arise from interfacing metal-organic molecules with the topological insulator spin-momentum locked surface states, which can be perturbed enhancing or suppressing spintronics-relevant properties such as spin coherence. Here we show results from an angle-resolved photemission spectroscopy (ARPES) and scanning tunnelling microscopy (STM) study of the prototypical cobalt phthalocyanine (CoPc)/Bi2Se3 interface. We demonstrate that that the hybrid interface can act on the topological protection of the surface and bury the Dirac cone below the first quintuple layer.
Collapse
Affiliation(s)
- Marco Caputo
- Laboratoire de Physique des Solides, CNRS, Universitè Paris-Sud, Université Paris-Saclay , 91405 Orsay Cedex, France
- Laboratory Micro & Nano-Carbon, Elettra - Sincrotrone Trieste S.C.p.A., s.s.14 Km 163.5, 34149 Trieste, Italy
| | - Mirko Panighel
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and The Barcelona Institute of Science and Technology, Campus UAB, Bellaterra, 08193 Barcelona, Spain
- Laboratory Micro & Nano-Carbon, Elettra - Sincrotrone Trieste S.C.p.A., s.s.14 Km 163.5, 34149 Trieste, Italy
| | - Simone Lisi
- Dipartimento di Fisica, Università di Roma La Sapienza , Piazzale A. Moro 5, 00185 Roma, Italy
- Institut Néel, CNRS/UGA UPR2940, 25 Rue des Martyrs BP 166, 38042 Grenoble, France
| | - Lama Khalil
- Laboratoire de Physique des Solides, CNRS, Universitè Paris-Sud, Université Paris-Saclay , 91405 Orsay Cedex, France
- Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, BP48, 91192 Gif-sur-Yvette Cedex, France
| | - Giovanni Di Santo
- Laboratory Micro & Nano-Carbon, Elettra - Sincrotrone Trieste S.C.p.A., s.s.14 Km 163.5, 34149 Trieste, Italy
| | - Evangelos Papalazarou
- Laboratoire de Physique des Solides, CNRS, Universitè Paris-Sud, Université Paris-Saclay , 91405 Orsay Cedex, France
| | - Andrzej Hruban
- Institute of Electronic Materials Technology, 01-919 Warsaw, Poland
| | - Marcin Konczykowski
- Laboratoire des Solides Irradiés, Ecole Polytechnique, CNRS, CEA, Université Paris-Saclay , 91128 Palaiseau Cedex, France
| | - Lia Krusin-Elbaum
- Department of Physics, The City College of New York, CUNY , New York, New York 10031, United States
| | - Ziya S Aliev
- Institute of Catalisys and Inorganic Chemistry, Institute of Physics, Azerbaijan National Academy of Sciences , AZ-1143, Baku, Azerbaijan
| | - Mahammad B Babanly
- Institute of Catalisys and Inorganic Chemistry, Institute of Physics, Azerbaijan National Academy of Sciences , AZ-1143, Baku, Azerbaijan
| | - Mikhail M Otrokov
- Donostia International Physics Center (DIPC), 20018 Donostia-San Sebastian, Spain
- Tomsk State University , 634050 Tomsk, Russia
| | - Antonio Politano
- Department of Physics, University of Calabria , via ponte Bucci 31/C, 87036 Rende (CS), Italy
| | - Evgueni V Chulkov
- Donostia International Physics Center (DIPC), 20018 Donostia-San Sebastian, Spain
- Department of Materials Physics, University of the Basque Country UPV/EHU , 20018 Donostia-San Sebastian, Spain
- Centro de Fı́sica de Materiales (CFM), Materials Physics Center (MPC), Centro Mixto CSIC-UPV/EHU, 20018 Donostia-San Sebastian, Spain
- Saint Petersburg State University , 198504 Saint Petersburg, Russia
| | - Andrés Arnau
- Donostia International Physics Center (DIPC), 20018 Donostia-San Sebastian, Spain
- Department of Materials Physics, University of the Basque Country UPV/EHU , 20018 Donostia-San Sebastian, Spain
- Centro de Fı́sica de Materiales (CFM), Materials Physics Center (MPC), Centro Mixto CSIC-UPV/EHU, 20018 Donostia-San Sebastian, Spain
| | - Vera Marinova
- Institute of Optical Materials and Technologies, "Acad. G. Bonchev" Str 109, Sofia, Bulgaria
| | - Pranab K Das
- Istituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, Area Science Park, s.s.14, Km 163.5, 34149 Trieste, Italy
- International Centre for Theoretical Physics, Strada Costiera 11, 34100 Trieste, Italy
| | - Jun Fujii
- Istituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, Area Science Park, s.s.14, Km 163.5, 34149 Trieste, Italy
| | - Ivana Vobornik
- Istituto Officina dei Materiali (IOM)-CNR, Laboratorio TASC, Area Science Park, s.s.14, Km 163.5, 34149 Trieste, Italy
| | - Luca Perfetti
- Laboratoire des Solides Irradiés, Ecole Polytechnique, CNRS, CEA, Université Paris-Saclay , 91128 Palaiseau Cedex, France
| | - Aitor Mugarza
- Catalan Institute of Nanoscience and Nanotechnology (ICN2), CSIC and The Barcelona Institute of Science and Technology, Campus UAB, Bellaterra, 08193 Barcelona, Spain
- ICREA - Instituciò Catalana de Recerca i Estudis Avancast, Lluis Companys 23, 08010 Barcelona, Spain
| | - Andrea Goldoni
- Laboratory Micro & Nano-Carbon, Elettra - Sincrotrone Trieste S.C.p.A., s.s.14 Km 163.5, 34149 Trieste, Italy
| | - Marino Marsi
- Laboratoire de Physique des Solides, CNRS, Universitè Paris-Sud, Université Paris-Saclay , 91405 Orsay Cedex, France
| |
Collapse
|
18
|
Kummer K, Fondacaro A, Jimenez E, Velez-Fort E, Amorese A, Aspbury M, Yakhou-Harris F, van der Linden P, Brookes NB. The high-field magnet endstation for X-ray magnetic dichroism experiments at ESRF soft X-ray beamline ID32. JOURNAL OF SYNCHROTRON RADIATION 2016; 23:464-73. [PMID: 26917134 PMCID: PMC5297906 DOI: 10.1107/s160057751600179x] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 01/29/2016] [Indexed: 05/27/2023]
Abstract
A new high-field magnet endstation for X-ray magnetic dichroism experiments has been installed and commissioned at the ESRF soft X-ray beamline ID32. The magnet consists of two split-pairs of superconducting coils which can generate up to 9 T along the beam and up to 4 T orthogonal to the beam. It is connected to a cluster of ultra-high-vacuum chambers that offer a comprehensive set of surface preparation and characterization techniques. The endstation and the beam properties have been designed to provide optimum experimental conditions for X-ray magnetic linear and circular dichroism experiments in the soft X-ray range between 400 and 1600 eV photon energy. User operation started in November 2014.
Collapse
Affiliation(s)
- K. Kummer
- European Synchrotron Radiation Facility, 71 Avenue des Martyrs, CS40220, F-38043 Grenoble Cedex 9, France
| | - A. Fondacaro
- European Synchrotron Radiation Facility, 71 Avenue des Martyrs, CS40220, F-38043 Grenoble Cedex 9, France
| | - E. Jimenez
- European Synchrotron Radiation Facility, 71 Avenue des Martyrs, CS40220, F-38043 Grenoble Cedex 9, France
| | - E. Velez-Fort
- European Synchrotron Radiation Facility, 71 Avenue des Martyrs, CS40220, F-38043 Grenoble Cedex 9, France
| | - A. Amorese
- European Synchrotron Radiation Facility, 71 Avenue des Martyrs, CS40220, F-38043 Grenoble Cedex 9, France
| | - M. Aspbury
- European Synchrotron Radiation Facility, 71 Avenue des Martyrs, CS40220, F-38043 Grenoble Cedex 9, France
| | - F. Yakhou-Harris
- European Synchrotron Radiation Facility, 71 Avenue des Martyrs, CS40220, F-38043 Grenoble Cedex 9, France
| | - P. van der Linden
- European Synchrotron Radiation Facility, 71 Avenue des Martyrs, CS40220, F-38043 Grenoble Cedex 9, France
| | - N. B. Brookes
- European Synchrotron Radiation Facility, 71 Avenue des Martyrs, CS40220, F-38043 Grenoble Cedex 9, France
| |
Collapse
|
19
|
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] [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.
Collapse
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
| |
Collapse
|
20
|
Carrier-mediated ferromagnetism in the magnetic topological insulator Cr-doped (Sb,Bi)2Te3. Nat Commun 2015; 6:8913. [PMID: 26582485 PMCID: PMC4673827 DOI: 10.1038/ncomms9913] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2014] [Accepted: 10/15/2015] [Indexed: 11/22/2022] Open
Abstract
Magnetically doped topological insulators, possessing an energy gap created at the Dirac point through time-reversal-symmetry breaking, are predicted to exhibit exotic phenomena including the quantized anomalous Hall effect and a dissipationless transport, which facilitate the development of low-power-consumption devices using electron spins. Although several candidates of magnetically doped topological insulators were demonstrated to show long-range magnetic order, the realization of the quantized anomalous Hall effect is so far restricted to the Cr-doped (Sb,Bi)2Te3 system at extremely low temperature; however, the microscopic origin of its ferromagnetism is poorly understood. Here we present an element-resolved study for Cr-doped (Sb,Bi)2Te3 using X-ray magnetic circular dichroism to unambiguously show that the long-range magnetic order is mediated by the p-hole carriers of the host lattice, and the interaction between the Sb(Te) p and Cr d states is crucial. Our results are important for material engineering in realizing the quantized anomalous Hall effect at higher temperatures. Magnetically doped topological insulators may exhibit exotic transport phenomena such as the quantum anomalous Hall effect, however the underlying mechanisms of ferromagnetic order are currently debated. Here, the authors reveal stabilized ferromagnetism in Cr-doped (Sb,Bi)2Te3 mediated by Te and Sb p-hole carriers.
Collapse
|
21
|
Yang HH, Chu YH, Lu CI, Butler CJ, Sankar R, Chou FC, Lin MT. Organic Monolayer Protected Topological Surface State. NANO LETTERS 2015; 15:6896-6900. [PMID: 26393876 DOI: 10.1021/acs.nanolett.5b02811] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Perylene-3,4,9,10-tetracarboxylic dianhydride (PTCDA)/Bi2Se3 and Fe/PTCDA/Bi2Se3 heterointerfaces are investigated using scanning tunneling microscopy and spectroscopy. The close-packed self-assembled PTCDA monolayer possesses big molecular band gap and weak molecule-substrate interactions, which leaves the Bi2Se3 topological surface state intact under PTCDA. Formation of Fe-PTCDA hybrids removes interactions between the Fe dopant and the Bi2Se3 surface, such as doping effects and Coulomb scattering. Our findings reveal the functionality of PTCDA to prevent dopant disturbances in the TSS and provide an effective alternative for interface designs of realistic TI devices.
Collapse
Affiliation(s)
| | | | | | | | - Raman Sankar
- Institute of Atomic and Molecular Sciences, Academia Sinica , Taipei 10617, Taiwan
| | - Fang-Cheng Chou
- National Synchrotron Radiation Research Center , Hsinchu 30076, Taiwan
- Taiwan Consortium of Emergent Crystalline Materials (TCECM), Ministry of Science and Technology , Taipei 10622, Taiwan
| | - Minn-Tsong Lin
- Institute of Atomic and Molecular Sciences, Academia Sinica , Taipei 10617, Taiwan
| |
Collapse
|
22
|
Heinrich BW, Braun L, Pascual JI, Franke KJ. Tuning the Magnetic Anisotropy of Single Molecules. NANO LETTERS 2015; 15:4024-8. [PMID: 25942560 DOI: 10.1021/acs.nanolett.5b00987] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/12/2023]
Abstract
The magnetism of single atoms and molecules is governed by the atomic scale environment. In general, the reduced symmetry of the surrounding splits the d states and aligns the magnetic moment along certain favorable directions. Here, we show that we can reversibly modify the magnetocrystalline anisotropy by manipulating the environment of single iron(II) porphyrin molecules adsorbed on Pb(111) with the tip of a scanning tunneling microscope. When we decrease the tip-molecule distance, we first observe a small increase followed by an exponential decrease of the axial anisotropy on the molecules. This is in contrast to the monotonous increase observed earlier for the same molecule with an additional axial Cl ligand ( Nat. Phys. 2013 , 9 , 765 ). We ascribe the changes in the anisotropy of both species to a deformation of the molecules in the presence of the attractive force of the tip, which leads to a change in the d level alignment. These experiments demonstrate the feasibility of a precise tuning of the magnetic anisotropy of an individual molecule by mechanical control.
Collapse
Affiliation(s)
- Benjamin W Heinrich
- †Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Lukas Braun
- †Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| | - Jose I Pascual
- †Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
- ‡CIC nanoGUNE, 20018 Donostia-San Sebastián, Spain
- §Ikerbasque, Basque Foundation for Science, 48011 Bilbao, Spain
| | - Katharina J Franke
- †Fachbereich Physik, Freie Universität Berlin, Arnimallee 14, 14195 Berlin, Germany
| |
Collapse
|
23
|
Wang E, Tang P, Wan G, Fedorov AV, Miotkowski I, Chen YP, Duan W, Zhou S. Robust gapless surface state and Rashba-splitting bands upon surface deposition of magnetic Cr on Bi2Se3. NANO LETTERS 2015; 15:2031-2036. [PMID: 25710329 DOI: 10.1021/nl504900s] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The interaction between magnetic impurities and the gapless surface state is of critical importance for realizing novel quantum phenomena and new functionalities in topological insulators. By combining angle-resolved photoemission spectroscopic experiments with density functional theory calculations, we show that surface deposition of Cr atoms on Bi2Se3 does not lead to gap opening of the surface state at the Dirac point, indicating the absence of long-range out-of-plane ferromagnetism down to our measurement temperature of 15 K. This is in sharp contrast to bulk Cr doping, and the origin is attributed to different Cr occupation sites. These results highlight the importance of nanoscale configuration of doped magnetic impurities in determining the electronic and magnetic properties of topological insulators.
Collapse
Affiliation(s)
- Eryin Wang
- State Key Laboratory of Low Dimensional Quantum Physics and Department of Physics, Tsinghua University , Beijing 100084, P.R. China
| | | | | | | | | | | | | | | |
Collapse
|
24
|
Yu Y, She L, Fu H, Huang M, Li H, Meng S, Cao G. Kondo effect mediated topological protection: Co on Sb(111). ACS NANO 2014; 8:11576-11582. [PMID: 25350607 DOI: 10.1021/nn504817m] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We report on a Kondo effect on Co/Sb(111) mediating topological protection of the surface states against local magnetic perturbations. A sharp scanning tunneling spectroscopic peak near the Fermi energy is interpreted as a fingerprint of the Kondo resonance with a high Kondo temperature of about 200 K. Density function theory calculations reveal that the protruding Co adatoms are responsible for the Kondo peak, while the Co atoms underneath present as nonmagnetic impurities. By identifying the quasiparticle interference wavevectors, we demonstrate that only scattering channels related to backscattering confinements are observed for surfaces with and without the Co adsorption. It suggests that the Kondo effect suppresses the backscattering of the topological surface states and may help to expand the functionality of magnetically coupled topological materials for spintronics applications.
Collapse
Affiliation(s)
- Yinghui Yu
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences , Wuhan 430071, China
| | | | | | | | | | | | | |
Collapse
|
25
|
Signatures of Dirac fermion-mediated magnetic order. Nat Commun 2014; 5:5349. [DOI: 10.1038/ncomms6349] [Citation(s) in RCA: 63] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2014] [Accepted: 09/23/2014] [Indexed: 11/09/2022] Open
|
26
|
van der Laan G, Figueroa AI. X-ray magnetic circular dichroism—A versatile tool to study magnetism. Coord Chem Rev 2014. [DOI: 10.1016/j.ccr.2014.03.018] [Citation(s) in RCA: 153] [Impact Index Per Article: 15.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
|
27
|
Zhao K, Lv YF, Ji SH, Ma X, Chen X, Xue QK. Scanning tunneling microscopy studies of topological insulators. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:394003. [PMID: 25214502 DOI: 10.1088/0953-8984/26/39/394003] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Scanning tunneling microscopy (STM), with surface sensitivity, is an ideal tool to probe the intriguing properties of the surface state of topological insulators (TIs) and topological crystalline insulators (TCIs). We summarize the recent progress on those topological phases revealed by STM studies. STM observations have directly confirmed the existence of the topological surface states and clearly revealed their novel properties. We also discuss STM work on magnetic doped TIs, topological superconductors and crystalline symmetry-protected surface states in TCIs. The studies have greatly promoted our understanding of the exotic properties of the new topological phases, as well as put forward new challenges. STM will continue to play an important role in this rapidly growing field from the point view of both fundamental physics and applications.
Collapse
Affiliation(s)
- Kun Zhao
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
| | | | | | | | | | | |
Collapse
|
28
|
Atomic and electronic structure of an alloyed topological insulator, Bi1.5Sb0.5Te1.7Se1.3. Sci Rep 2014; 3:2656. [PMID: 24030733 PMCID: PMC3772381 DOI: 10.1038/srep02656] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2013] [Accepted: 08/27/2013] [Indexed: 11/08/2022] Open
Abstract
Bi2-xSbxTe3-ySey has been argued to exhibit both topological surface states and insulating bulk states, but has not yet been studied with local probes on the atomic scale. Here we report on the atomic and electronic structures of Bi1.5Sb0.5Te1.7Se1.3 studied using scanning tunnelling microscopy (STM) and spectroscopy (STS). Although there is significant surface disorder due to alloying of constituent atoms, cleaved surfaces of the crystals present a well-ordered hexagonal lattice with 10 Å high quintuple layer steps. STS results reflect the band structure and indicate that the surface state and Fermi energy are both located inside the energy gap. In particular, quasi-particle interference patterns from electron scattering demonstrate that the surface states possess linear dispersion and chirality from spin texture, thus verifying its topological nature. This finding demonstrates that alloying is a promising route to achieve full suppression of bulk conduction in topological insulators whilst keeping the topological surface state intact.
Collapse
|
29
|
Shen L, Zeng M, Lu Y, Yang M, Feng YP. Simultaneous magnetic and charge doping of topological insulators with carbon. PHYSICAL REVIEW LETTERS 2013; 111:236803. [PMID: 24476296 DOI: 10.1103/physrevlett.111.236803] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2013] [Revised: 05/25/2013] [Indexed: 06/03/2023]
Abstract
A two-step doping process, magnetic followed by charge or vice versa, is required to produce massive topological surface states (TSS) in topological insulators for many physics and device applications. Here, we demonstrate simultaneous magnetic and hole doping achieved with a single dopant, carbon, in Bi2Se3 by first-principles calculations. Carbon substitution for Se (C(Se)) results in an opening of a sizable surface Dirac gap (up to 82 meV), while the Fermi level remains inside the bulk gap and close to the Dirac point at moderate doping concentrations. The strong localization of 2p states of C(Se) favors spontaneous spin polarization via a p-p interaction and formation of ordered magnetic moments mediated by surface states. Meanwhile, holes are introduced into the system by C(Se). This dual function of carbon doping suggests a simple way to realize insulating massive TSS.
Collapse
Affiliation(s)
- Lei Shen
- Department of Physics, 2 Science Drive 3, National University of Singapore, Singapore 117542, Singapore
| | - Minggang Zeng
- Department of Physics, 2 Science Drive 3, National University of Singapore, Singapore 117542, Singapore
| | - Yunhao Lu
- Department of Physics, 2 Science Drive 3, National University of Singapore, Singapore 117542, Singapore
| | - Ming Yang
- Department of Physics, 2 Science Drive 3, National University of Singapore, Singapore 117542, Singapore
| | - Yuan Ping Feng
- Department of Physics, 2 Science Drive 3, National University of Singapore, Singapore 117542, Singapore
| |
Collapse
|
30
|
Schmidt TM, Miwa RH, Fazzio A. Carrier-mediated magnetism in transition metal doped Bi₂Se₃ topological insulator. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2013; 25:445003. [PMID: 24056032 DOI: 10.1088/0953-8984/25/44/445003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
The Dirac surface states of topological insulators are protected by time-reversal symmetry, suppressing backscattering. Magnetic impurities adsorbed on the surface of topological insulators are expected to degrade the coherence of these protected surface states, breaking time-reversal symmetry. Some results are in agreement with this prediction. There are others where no bandgap opening was observed. Here, based upon first principles calculations, we show that one mechanism that plays a key role in these controversial results is the intrinsic carrier concentration. The magnetic phase of Fe-, Co- and Ni-doped Bi2Se3 has been computed and compared to the same systems in the presence of n- or p-type doping. Our results show that the magnetic phase is dependent on both the carrier concentration and the magnetic impurity coverage, resulting in a phase diagram for the existence or not of the protected Dirac states.
Collapse
Affiliation(s)
- Tome M Schmidt
- Instituto de Física, Universidade Federal de Uberlândia, Caixa Postal 593, CEP 38400-902, Uberlândia, Minas Gerais, Brazil
| | | | | |
Collapse
|
31
|
Yang F, Song YR, Li H, Zhang KF, Yao X, Liu C, Qian D, Gao CL, Jia JF. Identifying magnetic anisotropy of the topological surface state of Cr(0.05)Sb(1.95)Te(3) with spin-polarized STM. PHYSICAL REVIEW LETTERS 2013; 111:176802. [PMID: 24206512 DOI: 10.1103/physrevlett.111.176802] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2013] [Revised: 05/24/2013] [Indexed: 06/02/2023]
Abstract
The surface magnetic property plays a key role in determining magnetic related quantum phenomena of magnetic topological insulators. Using spin-polarized scanning tunneling microscopy, we investigate the surface magnetism and anisotropy of a Cr doped topological insulator: Cr(0.05)Sb(1.95)Te(3). It is found that the topological surface state of Cr(0.05)Sb(1.95)Te(3) is spin polarized in the surface plane while the bulk shows a ferromagnetism with an out-of-plane easy axis. The upper and lower branch of the helical Dirac cone harbors the opposite spin polarization and the polarization at the Dirac point is zero. Our results show the complexity of surface magnetism of magnetic doped topological insulators.
Collapse
Affiliation(s)
- Fang Yang
- Department of Physics and Astronomy, Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education). Shanghai Jiao Tong University, Shanghai 200240, China
| | | | | | | | | | | | | | | | | |
Collapse
|
32
|
Ye M, Kuroda K, Takeda Y, Saitoh Y, Okamoto K, Zhu SY, Shirai K, Miyamoto K, Arita M, Nakatake M, Okuda T, Ueda Y, Shimada K, Namatame H, Taniguchi M, Kimura A. Perpendicular magnetic anisotropy with enhanced orbital moments of Fe adatoms on a topological surface of Bi2Se3. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2013; 25:232201. [PMID: 23670139 DOI: 10.1088/0953-8984/25/23/232201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
We have found a perpendicular magnetic anisotropy of iron adatoms on a surface of the prototypical three-dimensional topological insulator Bi2Se3 by using x-ray magnetic circular dichroism measurements. The orbital magnetic moment of Fe is strongly enhanced at lower coverage, where angle-resolved photoemission spectroscopy shows coexistence of non-trivial topological states at the surface.
Collapse
Affiliation(s)
- Mao Ye
- Hiroshima Synchrotron Radiation Center, Hiroshima University, 2-313 Kagamiyama, Higashi-Hiroshima, Japan
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
33
|
Schlenk T, Bianchi M, Koleini M, Eich A, Pietzsch O, Wehling TO, Frauenheim T, Balatsky A, Mi JL, Iversen BB, Wiebe J, Khajetoorians AA, Hofmann P, Wiesendanger R. Controllable magnetic doping of the surface state of a topological insulator. PHYSICAL REVIEW LETTERS 2013; 110:126804. [PMID: 25166834 DOI: 10.1103/physrevlett.110.126804] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/08/2012] [Indexed: 05/04/2023]
Abstract
A combined experimental and theoretical study of doping individual Fe atoms into Bi(2)Se(3) is presented. It is shown through a scanning tunneling microscopy study that single Fe atoms initially located at hollow sites on top of the surface (adatoms) can be incorporated into subsurface layers by thermally activated diffusion. Angle-resolved photoemission spectroscopy in combination with ab initio calculations suggest that the doping behavior changes from electron donation for the Fe adatom to neutral or electron acceptance for Fe incorporated into substitutional Bi sites. According to first principles calculations within density functional theory, these Fe substitutional impurities retain a large magnetic moment, thus presenting an alternative scheme for magnetically doping the topological surface state. For both types of Fe doping, we see no indication of a gap at the Dirac point.
Collapse
Affiliation(s)
- T Schlenk
- Institute for Applied Physics, Universität Hamburg, D-20355 Hamburg, Germany
| | - M Bianchi
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University, 8000 Aarhus C, Denmark
| | - M Koleini
- Bremen Center for Computational Materials Science, University of Bremen, D-28359 Bremen, Germany
| | - A Eich
- Institute for Applied Physics, Universität Hamburg, D-20355 Hamburg, Germany
| | - O Pietzsch
- Institute for Applied Physics, Universität Hamburg, D-20355 Hamburg, Germany
| | - T O Wehling
- Bremen Center for Computational Materials Science, University of Bremen, D-28359 Bremen, Germany and Institute for Theoretical Physics, University of Bremen, D-28359 Bremen, Germany
| | - T Frauenheim
- Bremen Center for Computational Materials Science, University of Bremen, D-28359 Bremen, Germany
| | - A Balatsky
- Theoretical Division and Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA and Nordic Institute for Theoretical Physics (NORDITA), S-106 91 Stockholm, Sweden
| | - J-L Mi
- Center for Materials Crystallography, Department of Chemistry, Interdisciplinary Nanoscience Center, Aarhus University, 8000 Aarhus C, Denmark
| | - B B Iversen
- Center for Materials Crystallography, Department of Chemistry, Interdisciplinary Nanoscience Center, Aarhus University, 8000 Aarhus C, Denmark
| | - J Wiebe
- Institute for Applied Physics, Universität Hamburg, D-20355 Hamburg, Germany
| | - A A Khajetoorians
- Institute for Applied Physics, Universität Hamburg, D-20355 Hamburg, Germany
| | - Ph Hofmann
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University, 8000 Aarhus C, Denmark
| | - R Wiesendanger
- Institute for Applied Physics, Universität Hamburg, D-20355 Hamburg, Germany
| |
Collapse
|
34
|
Zhang F, Kane CL, Mele EJ. Surface state magnetization and chiral edge states on topological insulators. PHYSICAL REVIEW LETTERS 2013; 110:046404. [PMID: 25166181 DOI: 10.1103/physrevlett.110.046404] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/14/2012] [Indexed: 06/03/2023]
Abstract
We study the interaction between a ferromagnetically ordered medium and the surface states of a topological insulator with a general surface termination that were identified recently [F. Zhang et al. Phys. Rev. B 86, 081303(R) (2012)]. This interaction is strongly crystal face dependent and can generate chiral states along edges between crystal facets even for a uniform magnetization. While magnetization parallel to quintuple layers shifts the momentum of the Dirac point, perpendicular magnetization lifts the Kramers degeneracy at any Dirac points except on the side face, where the spectrum remains gapless and the Hall conductivity switches sign. Chiral states can be found at any edge that reverses the projection of the surface normal to the stacking direction of quintuple layers. Magnetization also weakly hybridizes noncleavage surfaces.
Collapse
Affiliation(s)
- Fan Zhang
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - C L Kane
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| | - E J Mele
- Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
| |
Collapse
|
35
|
Huang Z, Peng X, Yang H, He C, Xue L, Hao G, Zhang C, Liu W, Qi X, Zhong J. The structural, electronic and magnetic properties of bi-layered MoS2 with transition-metals doped in the interlayer. RSC Adv 2013. [DOI: 10.1039/c3ra41490f] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
|
36
|
Soriano D, Ortmann F, Roche S. Three-dimensional models of topological insulators: engineering of Dirac cones and robustness of the spin texture. PHYSICAL REVIEW LETTERS 2012; 109:266805. [PMID: 23368601 DOI: 10.1103/physrevlett.109.266805] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Indexed: 06/01/2023]
Abstract
We design three-dimensional models of topological insulator thin films, showing a tunability of the odd number of Dirac cones driven by the atomic-scale geometry at the boundaries. A single Dirac cone at the Γ-point can be obtained as well as full suppression of quantum tunneling between Dirac states at geometrically differentiated surfaces. The spin texture of surface states changes from a spin-momentum-locking symmetry to a surface spin randomization upon the introduction of bulk disorder. These findings illustrate the richness of the Dirac physics emerging in thin films of topological insulators and may prove utile for engineering Dirac cones and for quantifying bulk disorder in materials with ultraclean surfaces.
Collapse
Affiliation(s)
- David Soriano
- CIN2 (ICN-CSIC) and Universitat Autònoma de Barcelona, Catalan Institute of Nanotechnology, Campus de la UAB, 08193 Bellaterra (Barcelona), Spain
| | | | | |
Collapse
|
37
|
Zhang JM, Zhu W, Zhang Y, Xiao D, Yao Y. Tailoring magnetic doping in the topological insulator Bi2Se3. PHYSICAL REVIEW LETTERS 2012; 109:266405. [PMID: 23368592 DOI: 10.1103/physrevlett.109.266405] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Indexed: 06/01/2023]
Abstract
We theoretically investigate the possibility of establishing ferromagnetism in the topological insulator Bi2Se3 via magnetic doping of 3d transition metal elements. The formation energies, charge states, band structures, and magnetic properties of doped Bi2Se3 are studied using first-principles calculations within density functional theory. Our results show that Bi substitutional sites are energetically more favorable than interstitial sites for single impurities. Detailed electronic structure analysis reveals that Cr and Fe doped materials are still insulating in the bulk but the intrinsic band gap of Bi2Se3 is substantially reduced due to the strong hybridization between the d states of the dopants and the p states of the neighboring Se atoms. The calculated magnetic coupling suggests that Cr doped Bi2Se3 is possible to be both ferromagnetic and insulating, while Fe doped Bi2Se3 tends to be weakly antiferromagnetic.
Collapse
Affiliation(s)
- Jian-Min Zhang
- School of Physics, Beijing Institute of Technology, Beijing 100081, China
| | | | | | | | | |
Collapse
|
38
|
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. PHYSICAL REVIEW LETTERS 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] [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.
Collapse
Affiliation(s)
- M R Scholz
- Helmholtz-Zentrum Berlin für Materialien und Energie, Elektronenspeicherring BESSY II, Albert-Einstein-Strasse 15, D-12489 Berlin, Germany
| | | | | | | | | | | | | |
Collapse
|