1
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Breitkreiz M, Brouwer PW. Fermi-Arc Metals. PHYSICAL REVIEW LETTERS 2023; 130:196602. [PMID: 37243660 DOI: 10.1103/physrevlett.130.196602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/09/2023] [Revised: 03/09/2023] [Accepted: 04/27/2023] [Indexed: 05/29/2023]
Abstract
We predict a novel metallic state of matter that emerges in a Weyl-semimetal superstructure with spatially varying Weyl-node positions. In the new state, the Weyl nodes are stretched into extended, anisotropic Fermi surfaces, which can be understood as being built from Fermi arclike states. This "Fermi-arc metal" exhibits the chiral anomaly of the parental Weyl semimetal. However, unlike in the parental Weyl semimetal, in the Fermi-arc metal the "ultraquantum state," in which the anomalous chiral Landau level is the only state at the Fermi energy, is already reached for a finite energy window at zero magnetic field. The dominance of the ultraquantum state implies a universal low-field ballistic magnetoconductance and the absence of quantum oscillations, making the Fermi surface "invisible" to de Haas-van Alphen and Shubnikov-de Haas effects, although it signifies its presence in other response properties.
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Affiliation(s)
- Maxim Breitkreiz
- Dahlem Center for Complex Quantum Systems and Fachbereich Physik, Freie Universität Berlin, 14195 Berlin, Germany
| | - Piet W Brouwer
- Dahlem Center for Complex Quantum Systems and Fachbereich Physik, Freie Universität Berlin, 14195 Berlin, Germany
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2
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Nowak K, Jurczyszyn M, Chrobak M, Maćkosz K, Naumov A, Olszowska N, Rosmus M, Miotkowski I, Kozłowski A, Sikora M, Przybylski M. Influence of Doping on the Topological Surface States of Crystalline Bi2Se3 Topological Insulators. MATERIALS 2022; 15:ma15062083. [PMID: 35329534 PMCID: PMC8949243 DOI: 10.3390/ma15062083] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 03/01/2022] [Accepted: 03/04/2022] [Indexed: 02/04/2023]
Abstract
We present STM/STS, ARPES and magnetotransport studies of the surface topography and electronic structure of pristine Bi2Se3 in comparison to Bi1.96Mg0.04Se3 and Bi1.98Fe0.02Se3. The topography images reveal a large number of complex, triangle-shaped defects at the surface. The local electronic structure of both the defected and non-defected regions is examined by STS. The defect-related states shift together with the Dirac point observed in the undefected area, suggesting that the local electronic structure at the defects is influenced by doping in the same way as the electronic structure of the undefected surface. Additional information about the electronic structure of the samples is provided by ARPES, which reveals the dependence of the bulk and surface electronic bands on doping, including such parameters as the Fermi wave vector. The subtle changes of the surface electronic structure by doping are verified with magneto-transport measurements at low temperatures (200 mK) allowing the detection of Shubnikov-de Haas (SdH) quantum oscillations.
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Affiliation(s)
- Kamil Nowak
- Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, 30-059 Krakow, Poland; (K.N.); (M.C.); (K.M.); (A.K.); (M.P.)
- Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, 30-059 Krakow, Poland; (A.N.); (M.S.)
| | - Michał Jurczyszyn
- Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, 30-059 Krakow, Poland; (A.N.); (M.S.)
- Correspondence: ; Tel.: +48-12-617-5284
| | - Maciej Chrobak
- Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, 30-059 Krakow, Poland; (K.N.); (M.C.); (K.M.); (A.K.); (M.P.)
- Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, 30-059 Krakow, Poland; (A.N.); (M.S.)
| | - Krzysztof Maćkosz
- Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, 30-059 Krakow, Poland; (K.N.); (M.C.); (K.M.); (A.K.); (M.P.)
- Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, 30-059 Krakow, Poland; (A.N.); (M.S.)
| | - Andrii Naumov
- Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, 30-059 Krakow, Poland; (A.N.); (M.S.)
| | - Natalia Olszowska
- National Synchrotron Radiation Centre, Jagiellonian University, 30-392 Krakow, Poland; (N.O.); (M.R.)
| | - Marcin Rosmus
- National Synchrotron Radiation Centre, Jagiellonian University, 30-392 Krakow, Poland; (N.O.); (M.R.)
- Marian Smoluchowski Institute of Physics, Jagiellonian University, 30-348 Krakow, Poland
| | - Ireneusz Miotkowski
- Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907, USA;
| | - Andrzej Kozłowski
- Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, 30-059 Krakow, Poland; (K.N.); (M.C.); (K.M.); (A.K.); (M.P.)
| | - Marcin Sikora
- Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, 30-059 Krakow, Poland; (A.N.); (M.S.)
| | - Marek Przybylski
- Faculty of Physics and Applied Computer Science, AGH University of Science and Technology, 30-059 Krakow, Poland; (K.N.); (M.C.); (K.M.); (A.K.); (M.P.)
- Academic Centre for Materials and Nanotechnology, AGH University of Science and Technology, 30-059 Krakow, Poland; (A.N.); (M.S.)
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3
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Europium Doping Impact on the Properties of MBE Grown Bi 2Te 3 Thin Film. MATERIALS 2020; 13:ma13143111. [PMID: 32668572 PMCID: PMC7411847 DOI: 10.3390/ma13143111] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/11/2020] [Revised: 07/07/2020] [Accepted: 07/08/2020] [Indexed: 11/16/2022]
Abstract
The impact of europium doping on the electronic and structural properties of the topological insulator Bi2Te3 is studied in this paper. The crystallographic structure studied by electron diffraction and transmission microscopy confirms that grown by Molecular Beam Epitaxy (MBE) system film with the Eu content of about 3% has a trigonal structure with relatively large monocrystalline grains. The X-ray photoemission spectroscopy indicates that europium in Bi2Te3 matrix remains divalent and substitutes bismuth in a Bi2Te3 matrix. An exceptional ratio of the photoemission 4d multiplet components in Eu doped film was observed. However, some spatial inhomogeneity at the nanometer scale is revealed. Firstly, local conductivity measurements indicate that the surface conductivity is inhomogeneous and is correlated with a topographic image revealing possible coexistence of conducting surface states with insulating regions. Secondly, Time of Flight Secondary Ion Mass Spectrometry (TOF-SIMS) depth-profiling also shows partial chemical segregation. Such in-depth inhomogeneity has an impact on the lattice dynamics (phonon lifetime) evaluated by femtosecond spectroscopy. This unprecedented set of experimental investigations provides important insights for optimizing the process of growth of high-quality Eu-doped thin films of a Bi2Te3 topological insulator. Understanding such complex behaviors at the nanoscale level is a necessary step before considering topological insulator thin films as a component of innovative devices.
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4
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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.
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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
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5
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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.
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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
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6
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Jeong K, Park H, Chae J, Sim KI, Yang WJ, Kim JH, Hong SB, Kim JH, Cho MH. Topological Phase Control of Surface States in Bi 2Se 3 via Spin-Orbit Coupling Modulation through Interface Engineering between HfO 2-X. ACS APPLIED MATERIALS & INTERFACES 2020; 12:12215-12226. [PMID: 32073823 DOI: 10.1021/acsami.9b17555] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The direct control of topological surface states in topological insulators is an important prerequisite for the application of these materials. Conventional attempts to utilize magnetic doping, mechanical tuning, structural engineering, external bias, and external magnetic fields suffer from a lack of reversible switching and have limited tunability. We demonstrate the direct control of topological phases in a bismuth selenide (Bi2Se3) topological insulator in 3 nm molecular beam epitaxy-grown films through the hybridization of the topological surface states with the hafnium (Hf) d-orbitals in the topmost layer of an underlying oxygen-deficient hafnium oxide (HfO2) substrate. The higher angular momentum of the d-orbitals of Hf is hybridized strongly by topological insulators, thereby enhancing the spin-orbit coupling and perturbing the topological surface states asymmetry in Bi2Se3. As the oxygen defect is cured or generated reversibly by external electric fields, our research facilitates the complete electrical control of the topological phases of topological insulators by controlling the defect density in the adjacent transition metal oxide. In addition, this mechanism can be applied in other related topological materials such as Weyl and Dirac semimetals in future endeavors to facilitate practical applications in unit-element devices for quantum computing and quantum communication.
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Affiliation(s)
- Kwangsik Jeong
- Institute of Physics and Applied Physics, Yonsei University, Seoul 120-749, Republic of Korea
| | - Hanbum Park
- Institute of Physics and Applied Physics, Yonsei University, Seoul 120-749, Republic of Korea
| | - Jimin Chae
- Institute of Physics and Applied Physics, Yonsei University, Seoul 120-749, Republic of Korea
| | - Kyung-Ik Sim
- Institute of Physics and Applied Physics, Yonsei University, Seoul 120-749, Republic of Korea
| | - Won Jun Yang
- Institute of Physics and Applied Physics, Yonsei University, Seoul 120-749, Republic of Korea
| | - Jong-Hoon Kim
- Institute of Physics and Applied Physics, Yonsei University, Seoul 120-749, Republic of Korea
| | - Seok-Bo Hong
- Institute of Physics and Applied Physics, Yonsei University, Seoul 120-749, Republic of Korea
| | - Jae Hoon Kim
- Institute of Physics and Applied Physics, Yonsei University, Seoul 120-749, Republic of Korea
| | - Mann-Ho Cho
- Institute of Physics and Applied Physics, Yonsei University, Seoul 120-749, Republic of Korea
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7
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Abstract
This review briefly describes the development of synthetic topological insulator materials in the application of advanced electronic devices. As a new class of quantum matter, topological insulators with insulating bulk and conducting surface states have attracted attention in more and more research fields other than condensed matter physics due to their intrinsic physical properties, which provides an excellent basis for novel nanoelectronic, optoelectronic, and spintronic device applications. In comparison to the mechanically exfoliated samples, the newly emerging topological insulator nanostructures prepared with various synthetical approaches are more intriguing because the conduction contribution of the surface states can be significantly enhanced due to the larger surface-to-volume ratio, better manifesting the unique properties of the gapless surface states. So far, these synthetic topological insulator nanostructures have been implemented in different electrically accessible device platforms via electrical, magnetic and optical characterizations for material investigations and device applications, which will be introduced in this review.
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8
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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.
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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
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9
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Chang SJ, Chuang PY, Chong CW, Chen YJ, Andrew Huang JC, Chen PW, Tseng YC. Heterostructured ferromagnet-topological insulator with dual-phase magnetic properties. RSC Adv 2018; 8:7785-7791. [PMID: 35539151 PMCID: PMC9078499 DOI: 10.1039/c8ra00068a] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2018] [Accepted: 02/05/2018] [Indexed: 12/02/2022] Open
Abstract
The introduction of ferromagnetism at the surface of a topological insulator (TI) produces fascinating spin-charge phenomena. It has been assumed that these fascinating effects are associated with a homogeneous ferromagnetic (FM) layer possessing a single type of magnetic phase. However, we obtained phase separation within the FM layer of a Ni80Fe20/Bi2Se3 heterostructure. This phase separation was caused by the diffusion of Ni into Bi2Se3, forming a ternary magnetic phase of Ni:Bi2Se3. The inward diffusion of Ni led to the formation of an FeSe phase outward, transforming the original Ni80Fe20/Bi2Se3 into a sandwich structure comprising FeSe/Ni:Bi2Se3/Bi2Se3 with dual-phase magnetic characteristics similar to that driven by the proximity effect. Such a phenomenon might have been overlooked in previous studies with a strong focus on the proximity effect. X-ray magnetic spectroscopy revealed that FeSe and Ni:Bi2Se3 possess horizontal and perpendicular magnetic anisotropy, respectively. The overall magnetic order of the heterostructure can be easily tuned by adjusting the thickness of the Bi2Se3 as it compromises the magnetic orders of the two magnetic phases. This discovery is essential to the quantification of spin-charge phenomena in similar material combinations where the FM layer is composed of multiple elements.
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Affiliation(s)
- Shu-Jui Chang
- Department of Materials Science & Engineering, National Chiao Tung University Hsinchu Taiwan
| | - Pei-Yu Chuang
- Department of Physics, National Cheng Kung University Tainan Taiwan
| | - Cheong-Wei Chong
- Department of Physics, National Cheng Kung University Tainan Taiwan
| | - Yu-Jung Chen
- Department of Materials Science & Engineering, National Chiao Tung University Hsinchu Taiwan
| | - Jung-Chun Andrew Huang
- Department of Physics, National Cheng Kung University Tainan Taiwan
- Advanced Optoelectronic Technology Center, National Cheng Kung University Tainan Taiwan
- Taiwan Consortium of Emergent Crystalline Materials, Ministry of Science and Technology Taipei Taiwan
| | - Po-Wen Chen
- Division of Physics, Institute of Nuclear Energy Research Taoyuan Taiwan
| | - Yuan-Chieh Tseng
- Department of Materials Science & Engineering, National Chiao Tung University Hsinchu Taiwan
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10
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Takagaki Y, Herfort J, Ramsteiner M, Jahn U, Jenichen B. Overgrowth of Bi2Te3 nanoislands on Fe-based epitaxial ferromagnetic layers. CrystEngComm 2018. [DOI: 10.1039/c8ce00882e] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Bi2Te3 is deposited by hot wall epitaxy in an attempt to form nanosheets on epitaxially-grown ferromagnetic layers of Fe, Fe3Si and Co2FeSi.
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Affiliation(s)
- Yukihiko Takagaki
- Paul-Drude-Institut für Festkörperelektronik
- Leibniz-Institut im Forschungsverbund
- 10117 Berlin
- Germany
| | - Jens Herfort
- Paul-Drude-Institut für Festkörperelektronik
- Leibniz-Institut im Forschungsverbund
- 10117 Berlin
- Germany
| | - Manfred Ramsteiner
- Paul-Drude-Institut für Festkörperelektronik
- Leibniz-Institut im Forschungsverbund
- 10117 Berlin
- Germany
| | - Uwe Jahn
- Paul-Drude-Institut für Festkörperelektronik
- Leibniz-Institut im Forschungsverbund
- 10117 Berlin
- Germany
| | - Bernd Jenichen
- Paul-Drude-Institut für Festkörperelektronik
- Leibniz-Institut im Forschungsverbund
- 10117 Berlin
- Germany
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11
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Yeats AL, Mintun PJ, Pan Y, Richardella A, Buckley BB, Samarth N, Awschalom DD. Local optical control of ferromagnetism and chemical potential in a topological insulator. Proc Natl Acad Sci U S A 2017; 114:10379-10383. [PMID: 28900003 PMCID: PMC5625936 DOI: 10.1073/pnas.1713458114] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Many proposed experiments involving topological insulators (TIs) require spatial control over time-reversal symmetry and chemical potential. We demonstrate reconfigurable micron-scale optical control of both magnetization (which breaks time-reversal symmetry) and chemical potential in ferromagnetic thin films of Cr-(Bi,Sb)2Te3 grown on SrTiO3 By optically modulating the coercivity of the films, we write and erase arbitrary patterns in their remanent magnetization, which we then image with Kerr microscopy. Additionally, by optically manipulating a space charge layer in the underlying SrTiO3 substrates, we control the local chemical potential of the films. This optical gating effect allows us to write and erase p-n junctions in the films, which we study with photocurrent microscopy. Both effects are persistent and may be patterned and imaged independently on a few-micron scale. Dynamic optical control over both magnetization and chemical potential of a TI may be useful in efforts to understand and control the edge states predicted at magnetic domain walls in quantum anomalous Hall insulators.
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Affiliation(s)
- Andrew L Yeats
- Institute for Molecular Engineering, University of Chicago, Chicago, IL 60637
- Materials Science Division, Argonne National Laboratory, Argonne, IL 60439
| | - Peter J Mintun
- Institute for Molecular Engineering, University of Chicago, Chicago, IL 60637
| | - Yu Pan
- Materials Research Institute, The Pennsylvania State University, University Park PA 16802
- Department of Physics, The Pennsylvania State University, University Park PA 16802
| | - Anthony Richardella
- Materials Research Institute, The Pennsylvania State University, University Park PA 16802
- Department of Physics, The Pennsylvania State University, University Park PA 16802
| | - Bob B Buckley
- Institute for Molecular Engineering, University of Chicago, Chicago, IL 60637
| | - Nitin Samarth
- Materials Research Institute, The Pennsylvania State University, University Park PA 16802
- Department of Physics, The Pennsylvania State University, University Park PA 16802
| | - David D Awschalom
- Institute for Molecular Engineering, University of Chicago, Chicago, IL 60637;
- Materials Science Division, Argonne National Laboratory, Argonne, IL 60439
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12
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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.
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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
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13
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Majumder S, Jarvis K, Banerjee SK, Kavanagh KL. Interfacial reactions at Fe/topological insulator spin contacts. JOURNAL OF VACUUM SCIENCE AND TECHNOLOGY. B, NANOTECHNOLOGY & MICROELECTRONICS : MATERIALS, PROCESSING, MEASUREMENT, & PHENOMENA : JVST B 2017; 35:04F105. [PMID: 28713648 PMCID: PMC5500119 DOI: 10.1116/1.4991331] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/15/2017] [Revised: 06/15/2017] [Accepted: 06/16/2017] [Indexed: 06/07/2023]
Abstract
The authors study the composition and abruptness of the interfacial layers that form during deposition and patterning of a ferromagnet, Fe on a topological insulator (TI), Bi2Se3, Bi2Te3, and SiOx/Bi2Te3. Such structures are potentially useful for spintronics. Cross-sectional transmission electron microscopy, including interfacial elemental mapping, confirms that Fe reacts with Bi2Se3 near room temperature, forming an abrupt 5 nm thick FeSe0.92 single crystalline binary phase, predominantly (001) oriented, with lattice fringe spacing of 0.55 nm. In contrast, Fe/Bi2Te3 forms a polycrystalline Fe/TI interfacial alloy that can be prevented by the addition of an evaporated SiOx separating Fe from the TI.
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Affiliation(s)
- Sarmita Majumder
- Microelectronics Research Center, University of Texas, Austin, Texas 78758
| | - Karalee Jarvis
- Microelectronics Research Center, University of Texas, Austin, Texas 78758
| | - Sanjay K Banerjee
- Microelectronics Research Center, University of Texas, Austin, Texas 78758
| | - Karen L Kavanagh
- Department of Physics, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
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14
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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.
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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.
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15
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Kiraly B, Hauptmann N, Rudenko AN, Katsnelson MI, Khajetoorians AA. Probing Single Vacancies in Black Phosphorus at the Atomic Level. NANO LETTERS 2017; 17:3607-3612. [PMID: 28481547 PMCID: PMC5474690 DOI: 10.1021/acs.nanolett.7b00766] [Citation(s) in RCA: 38] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Revised: 05/04/2017] [Indexed: 05/26/2023]
Abstract
Utilizing a combination of low-temperature scanning tunneling microscopy/spectroscopy (STM/STS) and electronic structure calculations, we characterize the structural and electronic properties of single atomic vacancies within several monolayers of the surface of black phosphorus. We illustrate, with experimental analysis and tight-binding calculations, that we can depth profile these vacancies and assign them to specific sublattices within the unit cell. Measurements reveal that the single vacancies exhibit strongly anisotropic and highly delocalized charge density, laterally extended up to 20 atomic unit cells. The vacancies are then studied with STS, which reveals in-gap resonance states near the valence band edge and a strong p-doping of the bulk black phosphorus crystal. Finally, quasiparticle interference generated near these vacancies enables the direct visualization of the anisotropic band structure of black phosphorus.
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16
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Singh UR, Warmuth J, Markmann V, Wiebe J, Wiesendanger R. Structural and electronic properties of ultrathin FeSe films grown on Bi 2Se 3(0 0 0 1) studied by STM/STS. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:025004. [PMID: 27841999 DOI: 10.1088/0953-8984/29/2/025004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
We report scanning tunnelling microscopy and spectroscopy (STM/STS) studies on one and two unit cell (UC) high FeSe thin films grown on Bi2Se3(0 0 0 1). In our thin films, we find the tetragonal phase of FeSe and dumb-bell shaped defects oriented along Se-Se bond directions. In addition, we observe striped moiré patterns with a periodicity of (7.3 ± 0.1) nm generated by the mismatch between the FeSe lattice and the Bi2Se3 lattice. We could not find any signature of a superconducting gap in the tunneling spectra measured on the surface of one and two UC thick islands of FeSe down to 6.5 K. The spectra rather show an asymmetric behavior across and a finite density of states at the Fermi level (E F) resembling those taken in the normal state of bulk FeSe.
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Affiliation(s)
- Udai Raj Singh
- Department of Physics, University of Hamburg, D-20355 Hamburg, Germany
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17
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Manna S, Kamlapure A, Cornils L, Hänke T, Hedegaard EMJ, Bremholm M, Iversen BB, Hofmann P, Wiebe J, Wiesendanger R. Interfacial superconductivity in a bi-collinear antiferromagnetically ordered FeTe monolayer on a topological insulator. Nat Commun 2017; 8:14074. [PMID: 28094258 PMCID: PMC5247605 DOI: 10.1038/ncomms14074] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Accepted: 11/25/2016] [Indexed: 11/09/2022] Open
Abstract
The discovery of high-temperature superconductivity in Fe-based compounds triggered numerous investigations on the interplay between superconductivity and magnetism, and on the enhancement of transition temperatures through interface effects. It is widely believed that the emergence of optimal superconductivity is intimately linked to the suppression of long-range antiferromagnetic (AFM) order, although the exact microscopic picture remains elusive because of the lack of atomically resolved data. Here we present spin-polarized scanning tunnelling spectroscopy of ultrathin FeTe1-xSex (x=0, 0.5) films on bulk topological insulators. Surprisingly, we find an energy gap at the Fermi level, indicating superconducting correlations up to Tc∼6 K for one unit cell FeTe grown on Bi2Te3, in contrast to the non-superconducting bulk FeTe. The gap spatially coexists with bi-collinear AFM order. This finding opens perspectives for theoretical studies of competing orders in Fe-based superconductors and for experimental investigations of exotic phases in superconducting layers on topological insulators.
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Affiliation(s)
- S Manna
- Department of Physics, University of Hamburg, Jungiusstrasse 11, D-20355 Hamburg, Germany
| | - A Kamlapure
- Department of Physics, University of Hamburg, Jungiusstrasse 11, D-20355 Hamburg, Germany
| | - L Cornils
- Department of Physics, University of Hamburg, Jungiusstrasse 11, D-20355 Hamburg, Germany
| | - T Hänke
- Department of Physics, University of Hamburg, Jungiusstrasse 11, D-20355 Hamburg, Germany
| | - E M J Hedegaard
- Department of Chemistry and iNANO, Center for Materials Crystallography, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C, Denmark
| | - M Bremholm
- Department of Chemistry and iNANO, Center for Materials Crystallography, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C, Denmark
| | - B B Iversen
- Department of Chemistry and iNANO, Center for Materials Crystallography, Aarhus University, Langelandsgade 140, DK-8000 Aarhus C, Denmark
| | - Ph Hofmann
- Department of Physics and Astronomy, Interdisciplinary Nanoscience Center, Aarhus University, DK-8000 Aarhus C, Denmark
| | - J Wiebe
- Department of Physics, University of Hamburg, Jungiusstrasse 11, D-20355 Hamburg, Germany
| | - R Wiesendanger
- Department of Physics, University of Hamburg, Jungiusstrasse 11, D-20355 Hamburg, Germany
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18
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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.
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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
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19
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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.
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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
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20
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Gooth J, Zierold R, Sergelius P, Hamdou B, Garcia J, Damm C, Rellinghaus B, Pettersson HJ, Pertsova A, Canali C, Borg M, Nielsch K. Local Magnetic Suppression of Topological Surface States in Bi2Te3 Nanowires. ACS NANO 2016; 10:7180-7188. [PMID: 27351276 DOI: 10.1021/acsnano.6b03537] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Locally induced, magnetic order on the surface of a topological insulator nanowire could enable room-temperature topological quantum devices. Here we report on the realization of selective magnetic control over topological surface states on a single facet of a rectangular Bi2Te3 nanowire via a magnetic insulating Fe3O4 substrate. Low-temperature magnetotransport studies provide evidence for local time-reversal symmetry breaking and for enhanced gapping of the interfacial 1D energy spectrum by perpendicular magnetic-field components, leaving the remaining nanowire facets unaffected. Our results open up great opportunities for development of dissipation-less electronics and spintronics.
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Affiliation(s)
- Johannes Gooth
- Institute of Nanostructure and Solid State Physics, Universität Hamburg , Jungiusstrasse 11 B, 20355 Hamburg, Germany
- IBM Research-Zurich , Säumerstrasse 4, 8803 Rüschlikon, Switzerland
| | - Robert Zierold
- Institute of Nanostructure and Solid State Physics, Universität Hamburg , Jungiusstrasse 11 B, 20355 Hamburg, Germany
| | - Philip Sergelius
- Institute of Nanostructure and Solid State Physics, Universität Hamburg , Jungiusstrasse 11 B, 20355 Hamburg, Germany
| | - Bacel Hamdou
- Institute of Nanostructure and Solid State Physics, Universität Hamburg , Jungiusstrasse 11 B, 20355 Hamburg, Germany
| | - Javier Garcia
- Institute for Metallic Materials, IFW Dresden , Helmholtzstrasse 20, 01069 Dresden, Germany
| | - Christine Damm
- Institute for Metallic Materials, IFW Dresden , Helmholtzstrasse 20, 01069 Dresden, Germany
| | - Bernd Rellinghaus
- Institute for Metallic Materials, IFW Dresden , Helmholtzstrasse 20, 01069 Dresden, Germany
| | - Håkan Jan Pettersson
- Division of Solid State Physics and NanoLund, Lund University , Box 118, 22100 Lund, Sweden
- Center for Applied Mathematics and Physics, Halmstad University , Box 823, 30118 Halmstad, Sweden
| | - Anna Pertsova
- Department of Physics and Electrical Engineering, Linnaeus University , 39182 Kalmar, Sweden
| | - Carlo Canali
- Department of Physics and Electrical Engineering, Linnaeus University , 39182 Kalmar, Sweden
| | - Mattias Borg
- IBM Research-Zurich , Säumerstrasse 4, 8803 Rüschlikon, Switzerland
| | - Kornelius Nielsch
- Institute of Nanostructure and Solid State Physics, Universität Hamburg , Jungiusstrasse 11 B, 20355 Hamburg, Germany
- Institute for Metallic Materials, IFW Dresden , Helmholtzstrasse 20, 01069 Dresden, Germany
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21
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Dual nature of magnetic dopants and competing trends in topological insulators. Nat Commun 2016; 7:12027. [PMID: 27345240 PMCID: PMC4931223 DOI: 10.1038/ncomms12027] [Citation(s) in RCA: 64] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2016] [Accepted: 05/24/2016] [Indexed: 11/29/2022] Open
Abstract
Topological insulators interacting with magnetic impurities have been reported to host several unconventional effects. These phenomena are described within the framework of gapping Dirac quasiparticles due to broken time-reversal symmetry. However, the overwhelming majority of studies demonstrate the presence of a finite density of states near the Dirac point even once topological insulators become magnetic. Here, we map the response of topological states to magnetic impurities at the atomic scale. We demonstrate that magnetic order and gapless states can coexist. We show how this is the result of the delicate balance between two opposite trends, that is, gap opening and emergence of a Dirac node impurity band, both induced by the magnetic dopants. Our results evidence a more intricate and rich scenario with respect to the once generally assumed, showing how different electronic and magnetic states may be generated and controlled in this fascinating class of materials. Magnetic impurities break time reversal symmetry in topological insulators, but there has been disagreement between theory and experiment. Here, the authors study the response of topological states to magnetic dopants at the atomic level and show that, contrary to what generally believed, magnetic order and gapless states can coexist.
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22
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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: 16] [Impact Index Per Article: 2.0] [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.
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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
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23
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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.
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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
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24
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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.
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Affiliation(s)
- Kun Zhao
- State Key Laboratory of Low-Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
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25
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Sessi P, Bathon T, Kokh KA, Tereshchenko OE, Bode M. Probing the electronic properties of individual MnPc molecules coupled to topological states. NANO LETTERS 2014; 14:5092-5096. [PMID: 25111590 DOI: 10.1021/nl5017893] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Hybrid organic/inorganic interfaces have been widely reported to host emergent properties that go beyond those of their single constituents. Coupling molecules to the recently discovered topological insulators, which possess linearly dispersing and spin-momentum-locked Dirac fermions, may offer a promising platform toward new functionalities. Here, we report a scanning tunneling microscopy and spectroscopy study of the prototypical interface between MnPc molecules and a Bi2Te3 surface. MnPc is found to bind stably to the substrate through its central Mn atom. The adsorption process is only accompanied by a minor charge transfer across the interface, resulting in a moderately n-doped Bi2Te3 surface. More remarkably, topological states remain completely unaffected by the presence of the molecules, as evidenced by the absence of scattering patterns around adsorption sites. Interestingly, we show that, while the HOMO and LUMO orbitals closely resemble those of MnPc in the gas phase, a new hybrid state emerges through interaction with the substrate. Our results pave the way toward hybrid organic-topological insulator heterostructures, which may unveil a broad range of exciting and unknown phenomena.
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Affiliation(s)
- P Sessi
- Physikalisches Institut, Experimentelle Physik 2, Universität Würzburg , Am Hubland, 97074 Würzburg, Germany
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26
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Kröger P, Sologub S, Tegenkamp C, Pfnür H. Scattering of charge carriers by Cr impurities in magnetotransport on a Bi(1 1 1) ultra-thin film. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:225002. [PMID: 24810521 DOI: 10.1088/0953-8984/26/22/225002] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
In this investigation we tested the role of Cr impurities on the strongly spin-polarized surface states of ultra-thin epitaxially grown Bi(1 1 1) films by measuring surface magnetoconductance and the Hall effect in conjunction with low-energy electron diffraction at a low temperature (10 K). Compared with Fe and Co, investigated recently, Cr atoms turned out to have scattering cross-sections that are about a factor of three higher than the former atoms. Nevertheless, only a small electron donation (0.03 e/atom) was found for Cr. It also exhibits strong spin-orbit scattering, as judged from quantitative analysis of weak localization effects. As a result, all spin-dependent selection rules are gradually relaxed with increasing Cr concentration, so that the initially observed weak anti-localization shifts towards weak localization. The non-monotonic decrease of conductance as a function of Cr concentration, even at 10 K, indicates high diffusivity and activated adsorption into its final optimal adsorption site.
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Affiliation(s)
- P Kröger
- Institut für Festkörperphysik, Abteilung Atomare und Molekulare Strukturen, Leibniz Universität Hannover, Appelstr. 2, D-30167 Hannover, Germany
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27
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Li Y, Zou X, Li J, Zhou G. Ferromagnetism and topological surface states of manganese doped Bi2Te3: insights from density-functional calculations. J Chem Phys 2014; 140:124704. [PMID: 24697467 DOI: 10.1063/1.4869146] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Based on first-principles calculations, the electronic, magnetic, and topological characters of manganese (Mn) doped topological insulator Bi2Te3 were investigated. The Mn substitutionally doped Bi2Te3, where Mn atoms tend to be uniformly distributed, was shown to be p-type ferromagnetic, arising from hole-mediated Ruderman-Kittel-Kasuya-Yosida interaction. Mn doping leads to an intrinsic band splitting at Γ point, which is substantially different from that of nonmagnetic dopant. The topological surface state of Bi2Te3 is indeed gapped by Mn doping; however, the bulk conductance limits the appearance of an insulating state. Moreover, the n-type doping behavior of Bi2Te3 is derived from Mn entering into the van der Waals gap of Bi2Te3.
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Affiliation(s)
- Yuanchang Li
- National Center for Nanoscience and Technology, Beijing 100190, People's Republic of China
| | - Xiaolong Zou
- Department of Materials Science and Nanoengineering, Rice University, Houston, Texas 77005, USA
| | - Jia Li
- Key Laboratory of Thermal Management Engineering and Materials, Graduate School at Shenzhen, Tsinghua University, Shenzhen 518055, People's Republic of China
| | - Gang Zhou
- Department of Physics, Tsinghua University, Beijing 100084, People's Republic of China
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