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Kim SJ, Choi D, Kim KW, Lee KY, Kim DH, Hong S, Suh J, Lee C, Kim SK, Park TE, Koo HC. Interface Engineering of Magnetic Anisotropy in van der Waals Ferromagnet-based Heterostructures. ACS NANO 2021; 15:16395-16403. [PMID: 34608798 DOI: 10.1021/acsnano.1c05790] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Interface engineering is an effective approach to tune the magnetic properties of van der Waals (vdW) magnets and their heterostructures. The prerequisites for the practical utilization of vdW magnets and heterostructures are a quantitative analysis of their magnetic anisotropy and the ability to modulate their interfacial properties, which have been challenging to achieve with conventional methods. Here we characterize the magnetic anisotropy of Fe3GeTe2 layers by employing the magnetometric technique based on anomalous Hall measurements and confirm its intrinsic nature. In addition, on the basis of the thickness dependences of the anisotropy field, we identify the interfacial and bulk contributions. Furthermore, we demonstrate that the interfacial anisotropy in Fe3GeTe2-based heterostructures is locally controlled by adjacent layers, leading to the realization of multiple magnetic behaviors in a single channel. This work proposes that the magnetometric technique is a useful platform for investigating the intrinsic properties of vdW magnets and that functional devices can be realized by local interface engineering.
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Affiliation(s)
- Sung Jong Kim
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, Korea
- Center for Spintronics, Korea Institute of Science and Technology, Seoul 02792, Korea
| | - Dongwon Choi
- Center for Spintronics, Korea Institute of Science and Technology, Seoul 02792, Korea
- Display and Nanosystem Laboratory, Department of Electrical Engineering, Korea University, Seoul 02841, Korea
| | - Kyoung-Whan Kim
- Center for Spintronics, Korea Institute of Science and Technology, Seoul 02792, Korea
| | - Ki-Young Lee
- Center for Spintronics, Korea Institute of Science and Technology, Seoul 02792, Korea
| | - Duck-Ho Kim
- Center for Spintronics, Korea Institute of Science and Technology, Seoul 02792, Korea
| | - Seokmin Hong
- Center for Spintronics, Korea Institute of Science and Technology, Seoul 02792, Korea
| | - Joonki Suh
- Department of Materials Science and Engineering, Ulsan National Institute of Science and Technology, Ulsan 44919, Korea
| | - Changgu Lee
- School of Mechanical Engineering, Sungkyunkwan University, Suwon 16419, Korea
| | - Se Kwon Kim
- Department of Physics, Korea Advanced Institute of Science and Technology, Daejeon 34141, Korea
| | - Tae-Eon Park
- Center for Spintronics, Korea Institute of Science and Technology, Seoul 02792, Korea
| | - Hyun Cheol Koo
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, Korea
- Center for Spintronics, Korea Institute of Science and Technology, Seoul 02792, Korea
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Yamaguchi A, Ohkochi T, Oura M, Yamada K, Saiki T, Suzuki S, Utsumi Y, Nakao A. X-ray Photoemission Spectroscopy Study of Uniaxial Magnetic Anisotropy Induced in a Ni Layer Deposited on a LiNbO 3 Substrate. NANOMATERIALS 2021; 11:nano11041024. [PMID: 33923691 PMCID: PMC8073480 DOI: 10.3390/nano11041024] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/17/2021] [Revised: 04/05/2021] [Accepted: 04/10/2021] [Indexed: 11/16/2022]
Abstract
The competition between magnetic shape anisotropy and the induced uniaxial magnetic anisotropy in the heterojunction between a ferromagnetic layer and a ferroelectric substrate serves to control magnetic domain structures as well as magnetization reversal characteristics. The uniaxial magnetic anisotropy, originating from the symmetry breaking effect in the heterojunction, plays a significant role in modifying the characteristics of magnetization dynamics. Magnetoelastic phenomena are known to generate uniaxial magnetic anisotropy; however, the interfacial electronic states that may contribute to the uniaxial magnetic anisotropy have not yet been adequately investigated. Here, we report experimental evidence concerning the binding energy change in the ferromagnetic layer/ferroelectric substrate heterojunction using X-ray photoemission spectroscopy. The binding energy shifts, corresponding to the chemical shifts, reveal the binding states near the interface. Our results shed light on the origin of the uniaxial magnetic anisotropy induced from the heterojunction. This knowledge can provide a means for the simultaneous control of magnetism, mechanics, and electronics in a nano/microsystem consisting of ferromagnetic/ferroelectric materials.
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Affiliation(s)
- Akinobu Yamaguchi
- Laboratory of Advanced Science and Technology for Industry, University of Hyogo, 3-1-2 Kouto, Kamigori, Hyogo 678-1205, Japan; (S.S.); (Y.U.); (A.N.)
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan; (T.O.); (M.O.)
- Correspondence:
| | - Takuo Ohkochi
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan; (T.O.); (M.O.)
- Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5198, Japan
| | - Masaki Oura
- RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo, Hyogo 679-5148, Japan; (T.O.); (M.O.)
| | - Keisuke Yamada
- Department of Chemistry and Biomolecular Science, Faculty of Engineering, Gifu University, 1-1 Yanagido, Gifu City, Gifu 501-1193, Japan;
| | - Tsunemasa Saiki
- Manufacturing Technology Department, Hyogo Prefectural Institute of Technology, 3-1-12 Yukihira, Suma, Kobe 654-0037, Japan;
| | - Satoru Suzuki
- Laboratory of Advanced Science and Technology for Industry, University of Hyogo, 3-1-2 Kouto, Kamigori, Hyogo 678-1205, Japan; (S.S.); (Y.U.); (A.N.)
| | - Yuichi Utsumi
- Laboratory of Advanced Science and Technology for Industry, University of Hyogo, 3-1-2 Kouto, Kamigori, Hyogo 678-1205, Japan; (S.S.); (Y.U.); (A.N.)
| | - Aiko Nakao
- Laboratory of Advanced Science and Technology for Industry, University of Hyogo, 3-1-2 Kouto, Kamigori, Hyogo 678-1205, Japan; (S.S.); (Y.U.); (A.N.)
- Research Organization for Nano and Life Innovation, Waseda University, 513 Tsurumaki-cho, Waseda, Shijuku-ku, Tokyo 162-0041, Japan
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Koo HC, Kim SB, Kim H, Park TE, Choi JW, Kim KW, Go G, Oh JH, Lee DK, Park ES, Hong IS, Lee KJ. Rashba Effect in Functional Spintronic Devices. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e2002117. [PMID: 32930418 DOI: 10.1002/adma.202002117] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2020] [Revised: 05/28/2020] [Indexed: 06/11/2023]
Abstract
Exploiting spin transport increases the functionality of electronic devices and enables such devices to overcome physical limitations related to speed and power. Utilizing the Rashba effect at the interface of heterostructures provides promising opportunities toward the development of high-performance devices because it enables electrical control of the spin information. Herein, the focus is mainly on progress related to the two most compelling devices that exploit the Rashba effect: spin transistors and spin-orbit torque devices. For spin field-effect transistors, the gate-voltage manipulation of the Rashba effect and subsequent control of the spin precession are discussed, including for all-electric spin field-effect transistors. For spin-orbit torque devices, recent theories and experiments on interface-generated spin current are discussed. The future directions of manipulating the Rashba effect to realize fully integrated spin logic and memory devices are also discussed.
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Affiliation(s)
- Hyun Cheol Koo
- Center for Spintronics, Korea Institute of Science and Technology, Seoul, 02792, South Korea
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, 02841, South Korea
| | - Seong Been Kim
- Center for Spintronics, Korea Institute of Science and Technology, Seoul, 02792, South Korea
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, 02841, South Korea
| | - Hansung Kim
- Center for Spintronics, Korea Institute of Science and Technology, Seoul, 02792, South Korea
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, 02841, South Korea
| | - Tae-Eon Park
- Center for Spintronics, Korea Institute of Science and Technology, Seoul, 02792, South Korea
| | - Jun Woo Choi
- Center for Spintronics, Korea Institute of Science and Technology, Seoul, 02792, South Korea
| | - Kyoung-Whan Kim
- Center for Spintronics, Korea Institute of Science and Technology, Seoul, 02792, South Korea
| | - Gyungchoon Go
- Department of Materials Science and Engineering, Korea University, Seoul, 02841, South Korea
| | - Jung Hyun Oh
- Department of Materials Science and Engineering, Korea University, Seoul, 02841, South Korea
| | - Dong-Kyu Lee
- Department of Materials Science and Engineering, Korea University, Seoul, 02841, South Korea
| | - Eun-Sang Park
- Center for Spintronics, Korea Institute of Science and Technology, Seoul, 02792, South Korea
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, 02841, South Korea
| | - Ik-Sun Hong
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, 02841, South Korea
| | - Kyung-Jin Lee
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, 02841, South Korea
- Department of Materials Science and Engineering, Korea University, Seoul, 02841, South Korea
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Qaiumzadeh A, Ado IA, Duine RA, Titov M, Brataas A. Theory of the Interfacial Dzyaloshinskii-Moriya Interaction in Rashba Antiferromagnets. PHYSICAL REVIEW LETTERS 2018; 120:197202. [PMID: 29799247 DOI: 10.1103/physrevlett.120.197202] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/26/2017] [Revised: 01/31/2018] [Indexed: 06/08/2023]
Abstract
In antiferromagnetic (AFM) thin films, broken inversion symmetry or coupling to adjacent heavy metals can induce Dzyaloshinskii-Moriya (DM) interactions. Knowledge of the DM parameters is essential for understanding and designing exotic spin structures, such as hedgehog Skyrmions and chiral Néel walls, which are attractive for use in novel information storage technologies. We introduce a framework for computing the DM interaction in two-dimensional Rashba antiferromagnets. Unlike in Rashba ferromagnets, the DM interaction is not suppressed even at low temperatures. The material parameters control both the strength and the sign of the interfacial DM interaction. Our results suggest a route toward controlling the DM interaction in AFM materials by means of doping and electric fields.
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Affiliation(s)
- Alireza Qaiumzadeh
- Center for Quantum Spintronics, Department of Physics, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
| | - Ivan A Ado
- Radboud University, Institute for Molecules and Materials, 6525 AJ Nijmegen, Netherlands
| | - Rembert A Duine
- Center for Quantum Spintronics, Department of Physics, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
- Institute for Theoretical Physics and Center for Extreme Matter and Emergent Phenomena, Utrecht University, Princetonplein 5, 3584 CC Utrecht, Netherlands
- Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, Netherlands
| | - Mikhail Titov
- Radboud University, Institute for Molecules and Materials, 6525 AJ Nijmegen, Netherlands
- ITMO University, Saint Petersburg 197101, Russia
| | - Arne Brataas
- Center for Quantum Spintronics, Department of Physics, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
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Kim KW, Lee KJ, Sinova J, Lee HW, Stiles MD. Spin-orbit torques from interfacial spin-orbit coupling for various interfaces. PHYSICAL REVIEW. B 2017; 96:104438. [PMID: 29333523 PMCID: PMC5761703 DOI: 10.1103/physrevb.96.104438] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
We use a perturbative approach to study the effects of interfacial spin-orbit coupling in magnetic multilayers by treating the two-dimensional Rashba model in a fully three-dimensional description of electron transport near an interface. This formalism provides a compact analytic expression for current-induced spin-orbit torques in terms of unperturbed scattering coefficients, allowing computation of spin-orbit torques for various contexts, by simply substituting scattering coefficients into the formulas. It applies to calculations of spin-orbit torques for magnetic bilayers with bulk magnetism, those with interface magnetism, a normal metal/ferromagnetic insulator junction, and a topological insulator/ferromagnet junction. It predicts a dampinglike component of spin-orbit torque that is distinct from any intrinsic contribution or those that arise from particular spin relaxation mechanisms. We discuss the effects of proximity-induced magnetism and insertion of an additional layer and provide formulas for in-plane current, which is induced by a perpendicular bias, anisotropic magnetoresistance, and spin memory loss in the same formalism.
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Affiliation(s)
- Kyoung-Whan Kim
- Institut für Physik, Johannes Gutenberg Universität Mainz, Mainz 55128, Germany
- Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
- Maryland NanoCenter, University of Maryland, College Park, Maryland 20742, USA
| | - Kyung-Jin Lee
- Department of Materials Science and Engineering, Korea University, Seoul 02841, Korea
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, Korea
| | - Jairo Sinova
- Institut für Physik, Johannes Gutenberg Universität Mainz, Mainz 55128, Germany
- Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, 162 53 Praha 6 Czech Republic
| | - Hyun-Woo Lee
- PCTP and Department of Physics, Pohang University of Science and Technology, Pohang 37673, Korea
| | - M D Stiles
- Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
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Kim J, Kim KW, Wang H, Sinova J, Wu R. Understanding the Giant Enhancement of Exchange Interaction in Bi_{2}Se_{3}-EuS Heterostructures. PHYSICAL REVIEW LETTERS 2017; 119:027201. [PMID: 28753347 DOI: 10.1103/physrevlett.119.027201] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/21/2016] [Indexed: 06/07/2023]
Abstract
A recent experiment indicated that a ferromagnetic EuS film in contact with a topological insulator Bi_{2}Se_{3} might show a largely enhanced Curie temperature and perpendicular magnetic anisotropy [F. Katmis et al., Nature (London) 533, 513 (2016).NATUAS0028-083610.1038/nature17635]. Through systematic density functional calculations, we demonstrate that in addition to the factor that Bi_{2}Se_{3} has a strong spin orbit coupling, the topological surface states are crucial to make these unusual behaviors robust as they hybridize with EuS states and extend rather far into the magnetic layers. The magnetic moments of Eu atoms are nevertheless not much enhanced, unlike what was reported in the experiment. Our results and model analyses provide useful insights for how these quantities are linked, and pave a way for the control of properties of magnetic films via contact with topological insulators.
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Affiliation(s)
- Jeongwoo Kim
- Department of Physics and Astronomy, University of California, Irvine, California 92697, USA
| | - Kyoung-Whan Kim
- Institut für Physik, Johannes Gutenberg Universität Mainz, Mainz, 55128, Germany
| | - Hui Wang
- Department of Physics and Astronomy, University of California, Irvine, California 92697, USA
| | - Jairo Sinova
- Institut für Physik, Johannes Gutenberg Universität Mainz, Mainz, 55128, Germany
- Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnická 10, 162 53 Praha 6, Czech Republic
| | - Ruqian Wu
- Department of Physics and Astronomy, University of California, Irvine, California 92697, USA
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