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Aishwarya A, Cai Z, Raghavan A, Romanelli M, Wang X, Li X, Gu GD, Hirsbrunner M, Hughes T, Liu F, Jiao L, Madhavan V. Spin-selective tunneling from nanowires of the candidate topological Kondo insulator SmB 6. Science 2022; 377:1218-1222. [PMID: 36074835 DOI: 10.1126/science.abj8765] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Incorporating relativistic physics into quantum tunneling can lead to exotic behavior such as perfect transmission through Klein tunneling. Here, we probed the tunneling properties of spin-momentum-locked relativistic fermions by designing and implementing a tunneling geometry that uses nanowires of the topological Kondo insulator candidate samarium hexaboride. The nanowires are attached to the end of scanning tunneling microscope tips and used to image the bicollinear stripe spin order in the antiferromagnet Fe1.03Te with a Neel temperature of about 50 kelvin. The antiferromagnetic stripes become invisible above 10 kelvin concomitant with the suppression of the topological surface states in the tip. We further demonstrate that the direction of spin polarization is tied to the tunneling direction. Our technique establishes samarium hexaboride nanowires as ideal conduits for spin-polarized currents.
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Affiliation(s)
- Anuva Aishwarya
- Department of Physics and Materials Research Laboratory, University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
| | - Zhuozhen Cai
- Department of Physics and Materials Research Laboratory, University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
| | - Arjun Raghavan
- Department of Physics and Materials Research Laboratory, University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
| | - Marisa Romanelli
- Department of Physics and Materials Research Laboratory, University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
| | - Xiaoyu Wang
- National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310, USA
| | - Xu Li
- State Key Laboratory of Optoelectronic Materials and Technologies, Guangdong Province Key Laboratory of Display Material and Technology, and School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510275, China
| | - G D Gu
- Condensed Matter Physics and Materials Science Department, Brookhaven National Laboratory, Upton, NY 11973, USA
| | - Mark Hirsbrunner
- Department of Physics and Materials Research Laboratory, University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
| | - Taylor Hughes
- Department of Physics and Materials Research Laboratory, University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
| | - Fei Liu
- State Key Laboratory of Optoelectronic Materials and Technologies, Guangdong Province Key Laboratory of Display Material and Technology, and School of Electronics and Information Technology, Sun Yat-sen University, Guangzhou 510275, China
| | - Lin Jiao
- Department of Physics and Materials Research Laboratory, University of Illinois Urbana-Champaign, Urbana, IL 61801, USA.,National High Magnetic Field Laboratory, Florida State University, Tallahassee, FL 32310, USA
| | - Vidya Madhavan
- Department of Physics and Materials Research Laboratory, University of Illinois Urbana-Champaign, Urbana, IL 61801, USA
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2
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Fledgling Quantum Spin Hall Effect in Pseudo Gap Phase of Bi2212. Symmetry (Basel) 2022. [DOI: 10.3390/sym14081746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
We studied the emergence of the quantum spin Hall (QSH) states for the pseudo-gap (PG) phase of Bi2212 bilayer system, assumed to be D-density wave (DDW) ordered, starting with a strong Rashba spin-orbit coupling (SOC) armed, and the time reversal symmetry (TRS) complaint Bloch Hamiltonian. The presence of strong SOC gives rise to non-trivial, spin-momentum locked spin texture tunable by electric field. The emergence of quantum anomalous Hall effect with TRS broken Chiral DDW Hamiltonian of Das Sarma et al. is found to be possible.
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3
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Cui Y, Chu Y, Pan Z, Xing Y, Huang S, Xu H. Anisotropic magnetoresistance as evidence of spin-momentum inter-locking in topological Kondo insulator SmB 6 nanowires. NANOSCALE 2021; 13:20417-20424. [PMID: 34878477 DOI: 10.1039/d1nr07047a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
SmB6, which opens up an insulating bulk gap due to hybridization between itinerant d-electrons and localized f-electrons below a critical temperature, turns out to be a topological Kondo insulator possessing exotic conducting states on its surface. However, measurement of the surface-states in SmB6 draws controversial conclusions, depending on the growth methods and experimental techniques used. Herein, we report anisotropic magnetoresistance (AMR) observed in the Kondo energy gap of a single SmB6 nanowire that is immune to magnetic dopant pollution and features a square cross-section to show high-symmetry crystal facets. The AMR clearly shows a cosine function of included angle θ between magnetic field and measuring current with a period of π. The positive AMR is interpreted by anisotropically lifting the topological protection of spin-momentum inter-locking surface-states by rotating the in-plane magnetic field, which, therefore, provides the transport evidence that supports the topologically nontrivial nature of the SmB6 surface-states.
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Affiliation(s)
- Yugui Cui
- Beijing Key Laboratory of Quantum Devices, Key Laboratory for the Physics and Chemistry of Nanodevices, and Department of Electronics, Peking University, Beijing, 100871, P. R. China.
| | - Yi Chu
- Beijing Key Laboratory of Quantum Devices, Key Laboratory for the Physics and Chemistry of Nanodevices, and Department of Electronics, Peking University, Beijing, 100871, P. R. China.
| | - Zhencun Pan
- Beijing Key Laboratory of Quantum Devices, Key Laboratory for the Physics and Chemistry of Nanodevices, and Department of Electronics, Peking University, Beijing, 100871, P. R. China.
| | - Yingjie Xing
- Beijing Key Laboratory of Quantum Devices, Key Laboratory for the Physics and Chemistry of Nanodevices, and Department of Electronics, Peking University, Beijing, 100871, P. R. China.
| | - Shaoyun Huang
- Beijing Key Laboratory of Quantum Devices, Key Laboratory for the Physics and Chemistry of Nanodevices, and Department of Electronics, Peking University, Beijing, 100871, P. R. China.
| | - Hongqi Xu
- Beijing Key Laboratory of Quantum Devices, Key Laboratory for the Physics and Chemistry of Nanodevices, and Department of Electronics, Peking University, Beijing, 100871, P. R. China.
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4
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On Strong f-Electron Localization Effect in a Topological Kondo Insulator. Symmetry (Basel) 2021. [DOI: 10.3390/sym13122245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
We study a strong f-electron localization effect on the surface state of a generic topological Kondo insulator (TKI) system by performing a mean-field theoretic (MFT) calculation within the framework of the periodic Anderson model (PAM) using the slave boson technique. The surface metallicity, together with bulk insulation, requires this type of localization. A key distinction between surface states in a conventional insulator and a topological insulator is that, along a course joining two time-reversal invariant momenta (TRIM) in the same BZ, there will be an intersection of these surface states, an even/odd number of times, with the Fermi energy inside the spectral gap. For an even (odd) number of surface state crossings, the surface states are topologically trivial (non-trivial). The symmetry consideration and the pictorial representation of the surface band structure obtained here show an odd number of crossings, leading to the conclusion that, at least within the PAM framework, the generic system is a strong topological insulator.
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5
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Wang H, Xiao Y, Guo M, Lee-Wong E, Yan GQ, Cheng R, Du CR. Spin Pumping of an Easy-Plane Antiferromagnet Enhanced by Dzyaloshinskii-Moriya Interaction. PHYSICAL REVIEW LETTERS 2021; 127:117202. [PMID: 34558931 DOI: 10.1103/physrevlett.127.117202] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2020] [Revised: 04/05/2021] [Accepted: 08/02/2021] [Indexed: 06/13/2023]
Abstract
Recently, antiferromagnets have received revived interest due to their significant potential for developing next-generation ultrafast magnetic storage. Here, we report dc spin pumping by the acoustic resonant mode in a canted easy-plane antiferromagnet α-Fe_{2}O_{3} enabled by the Dzyaloshinskii-Moriya interaction. Systematic angle and frequency-dependent measurements demonstrate that the observed spin-pumping signals arise from resonance-induced spin injection and inverse spin Hall effect in α-Fe_{2}O_{3}-metal heterostructures, mimicking the behavior of spin pumping in conventional ferromagnet-nonmagnet systems. The pure spin current nature is further corroborated by reversal of the polarity of spin-pumping signals when the spin detector is switched from platinum to tungsten which has an opposite sign of the spin Hall angle. Our results reveal the intriguing physics underlying the low-frequency spin dynamics and transport in canted easy-plane antiferromagnet-based heterostructures.
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Affiliation(s)
- Hailong Wang
- Center for Memory and Recording Research, University of California, San Diego, La Jolla, California 92093, USA
| | - Yuxuan Xiao
- Center for Memory and Recording Research, University of California, San Diego, La Jolla, California 92093, USA
| | - Mingda Guo
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
| | - Eric Lee-Wong
- Department of Physics, University of California, San Diego, La Jolla, California 92093, USA
| | - Gerald Q Yan
- Department of Physics, University of California, San Diego, La Jolla, California 92093, USA
| | - Ran Cheng
- Department of Physics and Astronomy, University of California, Riverside, California 92521, USA
- Department of Electrical and Computer Engineering, University of California, Riverside, California 92521, USA
| | - Chunhui Rita Du
- Center for Memory and Recording Research, University of California, San Diego, La Jolla, California 92093, USA
- Department of Physics, University of California, San Diego, La Jolla, California 92093, USA
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6
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Dc M, Chen JY, Peterson T, Sahu P, Ma B, Mousavi N, Harjani R, Wang JP. Observation of High Spin-to-Charge Conversion by Sputtered Bismuth Selenide Thin Films at Room Temperature. NANO LETTERS 2019; 19:4836-4844. [PMID: 31283247 DOI: 10.1021/acs.nanolett.8b05011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We investigated spin-to-charge conversion in sputtered Bi43Se57/Co20Fe60B20 heterostructures with in-plane magnetization at room temperature. High spin-to-charge conversion voltage signals have been observed at room temperature. The transmission electron microscope images show that the sputtered bismuth selenide thin films are nanogranular in structure. The spin-pumping voltage decreases with an increase in the size of the grains. The inverse Edelstein effect length (λIEE) is estimated to be as large as 0.32 nm. The large λIEE is due to the spin-momentum locking and is further enhanced by quantum confinement in the nanosized grains of the sputtered bismuth selenide films. We also investigated the effect on spin-pumping voltage due to the insertion of layers of MgO and Ag. The MgO insertion layer has almost completely suppressed the spin-pumping voltage, whereas the Ag insertion layer has enhanced the λIEE by 43%.
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Affiliation(s)
- Mahendra Dc
- School of Physics and Astronomy , University of Minnesota , Minneapolis , Minnesota 55455 , United States
| | - Jun-Yang Chen
- Department of Electrical and Computer Engineering , University of Minnesota , Minneapolis , Minnesota 55455 , United States
| | - Thomas Peterson
- School of Physics and Astronomy , University of Minnesota , Minneapolis , Minnesota 55455 , United States
| | - Protuysh Sahu
- School of Physics and Astronomy , University of Minnesota , Minneapolis , Minnesota 55455 , United States
| | - Bin Ma
- Department of Electrical and Computer Engineering , University of Minnesota , Minneapolis , Minnesota 55455 , United States
| | - Naser Mousavi
- Department of Electrical and Computer Engineering , University of Minnesota , Minneapolis , Minnesota 55455 , United States
| | - Ramesh Harjani
- Department of Electrical and Computer Engineering , University of Minnesota , Minneapolis , Minnesota 55455 , United States
| | - Jian-Ping Wang
- School of Physics and Astronomy , University of Minnesota , Minneapolis , Minnesota 55455 , United States
- Department of Electrical and Computer Engineering , University of Minnesota , Minneapolis , Minnesota 55455 , United States
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7
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Jiao L, Rößler S, Kasinathan D, Rosa PFS, Guo C, Yuan H, Liu CX, Fisk Z, Steglich F, Wirth S. Magnetic and defect probes of the SmB 6 surface state. SCIENCE ADVANCES 2018; 4:eaau4886. [PMID: 30430137 PMCID: PMC6226282 DOI: 10.1126/sciadv.aau4886] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/15/2018] [Accepted: 10/12/2018] [Indexed: 06/09/2023]
Abstract
The impact of nonmagnetic and magnetic impurities on topological insulators is a central focus concerning their fundamental physics and possible spintronics and quantum computing applications. Combining scanning tunneling spectroscopy with transport measurements, we investigate, both locally and globally, the effect of nonmagnetic and magnetic substituents in SmB6, a predicted topological Kondo insulator. Around the so-introduced substitutents and in accord with theoretical predictions, the surface states are locally suppressed with different length scales depending on the substituent's magnetic properties. For sufficiently high substituent concentrations, these states are globally destroyed. Similarly, using a magnetic tip in tunneling spectroscopy also resulted in largely suppressed surface states. Hence, a destruction of the surface states is always observed close to atoms with substantial magnetic moment. This points to the topological nature of the surface states in SmB6 and illustrates how magnetic impurities destroy the surface states from microscopic to macroscopic length scales.
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Affiliation(s)
- Lin Jiao
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
| | - Sahana Rößler
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
| | - Deepa Kasinathan
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
| | - Priscila F. S. Rosa
- Department of Physics and Astronomy, University of California, Irvine, CA 92697, USA
- Los Alamos National Laboratory, Los Alamos, NM 87545, USA
| | - Chunyu Guo
- Center for Correlated Matter, Zhejiang University, Hangzhou 310058, People’s Republic of China
- Department of Physics, Zhejiang University, Hangzhou 310058, People’s Republic of China
| | - Huiqiu Yuan
- Center for Correlated Matter, Zhejiang University, Hangzhou 310058, People’s Republic of China
- Department of Physics, Zhejiang University, Hangzhou 310058, People’s Republic of China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing 210093, People’s Republic of China
| | - Chao-Xing Liu
- Department of Physics, The Pennsylvania State University, University Park, PA 16802, USA
| | - Zachary Fisk
- Department of Physics and Astronomy, University of California, Irvine, CA 92697, USA
| | - Frank Steglich
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
- Center for Correlated Matter, Zhejiang University, Hangzhou 310058, People’s Republic of China
- Institute of Physics, Chinese Academy of Sciences, Beijing 100190, People’s Republic of China
| | - Steffen Wirth
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzer Straße 40, 01187 Dresden, Germany
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8
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Parfenov OE, Averyanov DV, Tokmachev AM, Karateev IA, Taldenkov AN, Kondratev OA, Storchak VG. Interface-Induced Anomalous Hall Conductivity in a Confined Metal. ACS APPLIED MATERIALS & INTERFACES 2018; 10:35589-35598. [PMID: 30247015 DOI: 10.1021/acsami.8b10962] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The mature silicon technological platform is actively explored for spintronic applications. Metal silicides are an integral part of the Si technology used as interconnects, gate electrodes, and diffusion barriers; their epitaxial integration with Si results in premier contacts. Recent studies highlight the exceptional role of electronic discontinuities at interfaces in the spin-dependent transport properties. Here, we report a new type of Hall conductivity driven by sharp interfaces of Eu silicide, an antiferromagnetic metal, sandwiched between two insulators - Si and SiO x. Quasi-ballistic transport probes spin-orbit coupling at the interfaces, in particular, charge-spin interconversion. Transverse magnetic field results in anomalous Hall effect signals of an unusual line shape. The interplay between opposite-sign signals from the two interfaces allows efficient control over the magnitude and sign of the overall effect. Selective engineering of interfaces singles out a particular spin signal. The two-channel nature of the effect and its high tunability offer new functional possibilities for future spintronic devices.
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Affiliation(s)
- Oleg E Parfenov
- National Research Center "Kurchatov Institute" , Kurchatov Sq. 1 , Moscow 123182 , Russia
| | - Dmitry V Averyanov
- National Research Center "Kurchatov Institute" , Kurchatov Sq. 1 , Moscow 123182 , Russia
| | - Andrey M Tokmachev
- National Research Center "Kurchatov Institute" , Kurchatov Sq. 1 , Moscow 123182 , Russia
| | - Igor A Karateev
- National Research Center "Kurchatov Institute" , Kurchatov Sq. 1 , Moscow 123182 , Russia
| | - Alexander N Taldenkov
- National Research Center "Kurchatov Institute" , Kurchatov Sq. 1 , Moscow 123182 , Russia
| | - Oleg A Kondratev
- National Research Center "Kurchatov Institute" , Kurchatov Sq. 1 , Moscow 123182 , Russia
| | - Vyacheslav G Storchak
- National Research Center "Kurchatov Institute" , Kurchatov Sq. 1 , Moscow 123182 , Russia
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9
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Li CH, van 't Erve OMJ, Yan C, Li L, Jonker BT. Electrical Detection of Charge-to-spin and Spin-to-Charge Conversion in a Topological Insulator Bi 2Te 3 Using BN/Al 2O 3 Hybrid Tunnel Barrier. Sci Rep 2018; 8:10265. [PMID: 29980749 PMCID: PMC6035191 DOI: 10.1038/s41598-018-28547-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Accepted: 06/18/2018] [Indexed: 11/18/2022] Open
Abstract
One of the most striking properties of three-dimensional topological insulators (TIs) is spin-momentum locking, where the spin is locked at right angles to momentum and hence an unpolarized charge current creates a net spin polarization. Alternatively, if a net spin is injected into the TI surface state system, it is distinctively associated with a unique carrier momentum and hence should generate a charge accumulation, as in the so-called inverse Edelstein effect. Here using a Fe/Al2O3/BN tunnel barrier, we demonstrate both effects in a single device in Bi2Te3: the electrical detection of the spin accumulation generated by an unpolarized current flowing through the surface states, and that of the charge accumulation generated by spins injected into the surface state system. This work is the first to utilize BN as part of a hybrid tunnel barrier on TI, where we observed a high spin polarization of 93% for the TI surfaces states. The reverse spin-to-charge measurement is an independent confirmation that spin and momentum are locked in the surface states of TI, and offers additional avenues for spin manipulation. It further demonstrates the robustness and versatility of electrical access to the spin system within TI surface states, an important step towards its utilization in TI-based spintronics devices.
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Affiliation(s)
- C H Li
- Materials Science and Technology Division, Naval Research Laboratory, Washington, DC, 20375, USA.
| | - O M J van 't Erve
- Materials Science and Technology Division, Naval Research Laboratory, Washington, DC, 20375, USA
| | - C Yan
- Department of Physics and Astronomy, West Virginia University, Morgantown, WV, 26506, USA
| | - L Li
- Department of Physics and Astronomy, West Virginia University, Morgantown, WV, 26506, USA
| | - B T Jonker
- Materials Science and Technology Division, Naval Research Laboratory, Washington, DC, 20375, USA
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10
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Tang C, Song Q, Chang CZ, Xu Y, Ohnuma Y, Matsuo M, Liu Y, Yuan W, Yao Y, Moodera JS, Maekawa S, Han W, Shi J. Dirac surface state-modulated spin dynamics in a ferrimagnetic insulator at room temperature. SCIENCE ADVANCES 2018; 4:eaas8660. [PMID: 29868645 PMCID: PMC5983918 DOI: 10.1126/sciadv.aas8660] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/27/2017] [Accepted: 04/20/2018] [Indexed: 06/08/2023]
Abstract
This work demonstrates markedly modified spin dynamics of magnetic insulator (MI) by the spin momentum-locked Dirac surface states of the adjacent topological insulator (TI), which can be harnessed for spintronic applications. As the Bi concentration x is systematically tuned in 5-nm-thick (Bi x Sb1-x )2Te3 TI films, the weight of the surface relative to bulk states peaks at x = 0.32 when the chemical potential approaches the Dirac point. At this concentration, the Gilbert damping constant of the precessing magnetization in 10-nm-thick Y3Fe5O12 MI films in the MI/TI heterostructures is enhanced by an order of magnitude, the largest among all concentrations. In addition, the MI acquires additional strong magnetic anisotropy that favors the in-plane orientation with similar Bi concentration dependence. These extraordinary effects of the Dirac surface states distinguish TI from other materials such as heavy metals in modulating spin dynamics of the neighboring magnetic layer.
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Affiliation(s)
- Chi Tang
- Department of Physics and Astronomy, University of California, Riverside, Riverside, CA 92521, USA
| | - Qi Song
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
| | - Cui-Zu Chang
- Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Department of Physics, The Pennsylvania State University, University Park, PA 16802, USA
| | - Yadong Xu
- Department of Physics and Astronomy, University of California, Riverside, Riverside, CA 92521, USA
| | - Yuichi Ohnuma
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai 319-1195, Ibaraki, Japan
| | - Mamoru Matsuo
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai 319-1195, Ibaraki, Japan
- Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Miyagi, Japan
| | - Yawen Liu
- Department of Physics and Astronomy, University of California, Riverside, Riverside, CA 92521, USA
| | - Wei Yuan
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
| | - Yunyan Yao
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
| | - Jagadeesh S. Moodera
- Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Sadamichi Maekawa
- Department of Physics, The Pennsylvania State University, University Park, PA 16802, USA
| | - Wei Han
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
| | - Jing Shi
- Department of Physics and Astronomy, University of California, Riverside, Riverside, CA 92521, USA
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11
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Liu T, Li Y, Gu L, Ding J, Chang H, Janantha PAP, Kalinikos B, Novosad V, Hoffmann A, Wu R, Chien CL, Wu M. Nontrivial Nature and Penetration Depth of Topological Surface States in SmB_{6} Thin Films. PHYSICAL REVIEW LETTERS 2018; 120:207206. [PMID: 29864320 DOI: 10.1103/physrevlett.120.207206] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2017] [Indexed: 06/08/2023]
Abstract
The nontrivial feature and penetration depth of the topological surface states (TSS) in SmB_{6} were studied via spin pumping. The experiments used SmB_{6} thin films grown on the bulk magnetic insulator Y_{3}Fe_{5}O_{12} (YIG). Upon the excitation of magnetization precession in the YIG, a spin current is generated in the SmB_{6} that produces, via spin-orbit coupling, a lateral electrical voltage in the film. This spin-pumping voltage signal becomes considerably stronger as the temperature decreases from 150 to 10 K, and such an enhancement most likely originates from the spin-momentum locking of the TSS and may thereby serve as evidence for the nontrivial nature of the TSS. The voltage data also show a unique film thickness dependence that suggests a TSS depth of ∼32 nm. The spin-pumping results are supported by transport measurements and analyses using a tight binding model.
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Affiliation(s)
- Tao Liu
- Department of Physics, Colorado State University, Fort Collins, Colorado 80523, USA
| | - Yufan Li
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - Lei Gu
- Department of Physics and Astronomy, University of California, Irvine, California 92697, USA
| | - Junjia Ding
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - Houchen Chang
- Department of Physics, Colorado State University, Fort Collins, Colorado 80523, USA
| | - P A Praveen Janantha
- Department of Physics, Colorado State University, Fort Collins, Colorado 80523, USA
| | - Boris Kalinikos
- Department of Physics, Colorado State University, Fort Collins, Colorado 80523, USA
- St. Petersburg Electrotechnical University, St. Petersburg 197376, Russia
| | - Valentyn Novosad
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - Axel Hoffmann
- Materials Science Division, Argonne National Laboratory, Lemont, Illinois 60439, USA
| | - Ruqian Wu
- Department of Physics and Astronomy, University of California, Irvine, California 92697, USA
| | - C L Chien
- Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - Mingzhong Wu
- Department of Physics, Colorado State University, Fort Collins, Colorado 80523, USA
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12
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Geng H, Luo W, Deng WY, Sheng L, Shen R, Xing DY. Theory of Inverse Edelstein Effect of The Surface States of A Topological Insulator. Sci Rep 2017; 7:3755. [PMID: 28623269 PMCID: PMC5473866 DOI: 10.1038/s41598-017-03346-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2017] [Accepted: 04/27/2017] [Indexed: 11/24/2022] Open
Abstract
The surface states of three-dimensional topological insulators possess the unique property of spin-momentum interlocking. This property gives rise to the interesting inverse Edelstein effect (IEE), in which an applied spin bias μ is converted to a measurable charge voltage difference V. We develop a semiclassical theory for the IEE of the surface states of Bi2Se3 thin films, which is applicable from the ballistic regime to diffusive regime. We find that the efficiency of the spin-charge conversion, defined as γ = V/μ, exhibits a universal dependence on the ratio between sample size and electron mean free path. The efficiency increases from γ = π/4 in the ballistic limit to γ = π in the diffusive limit, suggesting that sufficient strength of impurity scattering is favorable for the IEE.
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Affiliation(s)
- H Geng
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing, 210093, China
| | - W Luo
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing, 210093, China
| | - W Y Deng
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing, 210093, China
| | - L Sheng
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing, 210093, China.
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China.
| | - R Shen
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing, 210093, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
| | - D Y Xing
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing, 210093, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing University, Nanjing, 210093, China
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Song Q, Zhang H, Su T, Yuan W, Chen Y, Xing W, Shi J, Sun J, Han W. Observation of inverse Edelstein effect in Rashba-split 2DEG between SrTiO 3 and LaAlO 3 at room temperature. SCIENCE ADVANCES 2017; 3:e1602312. [PMID: 28345050 PMCID: PMC5357130 DOI: 10.1126/sciadv.1602312] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/21/2016] [Accepted: 02/03/2017] [Indexed: 05/14/2023]
Abstract
The Rashba physics has been intensively studied in the field of spin orbitronics for the purpose of searching novel physical properties and the ferromagnetic (FM) magnetization switching for technological applications. We report our observation of the inverse Edelstein effect up to room temperature in the Rashba-split two-dimensional electron gas (2DEG) between two insulating oxides, SrTiO3 and LaAlO3, with the LaAlO3 layer thickness from 3 to 40 unit cells (UC). We further demonstrate that the spin voltage could be markedly manipulated by electric field effect for the 2DEG between SrTiO3 and 3-UC LaAlO3. These results demonstrate that the Rashba-split 2DEG at the complex oxide interface can be used for efficient charge-and-spin conversion at room temperature for the generation and detection of spin current.
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Affiliation(s)
- Qi Song
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
| | - Hongrui Zhang
- Beijing National Laboratory for Condensed Matter Physics and the Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Tang Su
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
| | - Wei Yuan
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
| | - Yangyang Chen
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
| | - Wenyu Xing
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
| | - Jing Shi
- Department of Physics and Astronomy, University of California, Riverside, Riverside, CA 92521, USA
| | - Jirong Sun
- Beijing National Laboratory for Condensed Matter Physics and the Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Wei Han
- International Center for Quantum Materials, School of Physics, Peking University, Beijing 100871, China
- Collaborative Innovation Center of Quantum Matter, Beijing 100871, China
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