1
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Miura Y, Okabayashi J. Understanding magnetocrystalline anisotropy based on orbital and quadrupole moments. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:473001. [PMID: 36137512 DOI: 10.1088/1361-648x/ac943f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Accepted: 09/22/2022] [Indexed: 06/16/2023]
Abstract
Understanding magnetocrystalline anisotropy (MCA) is fundamentally important for developing novel magnetic materials. Therefore, clarifying the relationship between MCA and local physical quantities observed by spectroscopic measurements, such as the orbital and quadrupole moments, is necessary. In this review, we discuss MCA and the distortion effects in magnetic materials with transition metals (TMs) based on the orbital and quadrupole moments, which are related to the spin-conserving and spin-flip terms in the second-order perturbation calculations, respectively. We revealed that orbital moment stabilized the spin moment in the direction of the larger orbital moment, while the quadrupole moment stabilized the spin moment along the longitudinal direction of the spin-density distribution. The MCA of the magnetic materials with TMs and their interfaces can be determined from the competition between these two contributions. We showed that the perpendicular MCA of the face-centered cubic Ni with tensile tetragonal distortion arose from the orbital moment anisotropy, whereas that of Mn-Ga alloys originated from the quadrupole moment of spin density. In contrast, in the Co/Pd(111) multilayer and Fe/MgO(001), both the orbital moment anisotropy and quadrupole moment of spin density at the interfaces contributed to the perpendicular MCA. Understanding the MCA of magnetic materials and interfaces based on orbital and quadrupole moments is essential to design MCA of novel magnetic applications.
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Affiliation(s)
- Yoshio Miura
- Research Center for Magnetic and Spintronic Materials, National Institute for Materials Science (NIMS), Sengen 1-2-1, Tsukuba 305-0047, Japan
- Center for Spintronics Research Network (CSRN), Graduate School of Engineering Science, Osaka University, Machikaneyama 1-3, Toyonaka, Osaka 560-8531, Japan
| | - Jun Okabayashi
- Research Center for Spectrochemistry, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
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2
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González JA, Andrés JP, López Antón R. Applied Trends in Magnetic Rare Earth/Transition Metal Alloys and Multilayers. SENSORS (BASEL, SWITZERLAND) 2021; 21:5615. [PMID: 34451055 PMCID: PMC8402375 DOI: 10.3390/s21165615] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Revised: 08/14/2021] [Accepted: 08/17/2021] [Indexed: 11/16/2022]
Abstract
Ferrimagnetic thin films formerly played a very important role in the development of information storage technology. Now they are again at the forefront of the rising field of spintronics. From new, more efficient magnetic recording media and sensors based on spin valves to the promising technologies envisaged by all-optical switching, ferrimagnets offer singular properties that deserve to be studies both from the point of view of fundamental physics and for applications. In this review, we will focus on ferrimagnetic thin films based on the combination of rare earths (RE) and transition metals (TM).
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Affiliation(s)
- Juan Antonio González
- Instituto Regional de Investigación Científica Aplicada (IRICA), Universidad de Castilla-La Mancha, 13071 Ciudad Real, Spain; (J.A.G.); (J.P.A.)
- Departamento de Física Aplicada, Universidad de Castilla-La Mancha, 13071 Ciudad Real, Spain
| | - Juan Pedro Andrés
- Instituto Regional de Investigación Científica Aplicada (IRICA), Universidad de Castilla-La Mancha, 13071 Ciudad Real, Spain; (J.A.G.); (J.P.A.)
- Departamento de Física Aplicada, Universidad de Castilla-La Mancha, 13071 Ciudad Real, Spain
| | - Ricardo López Antón
- Instituto Regional de Investigación Científica Aplicada (IRICA), Universidad de Castilla-La Mancha, 13071 Ciudad Real, Spain; (J.A.G.); (J.P.A.)
- Departamento de Física Aplicada, Universidad de Castilla-La Mancha, 13071 Ciudad Real, Spain
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3
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Controllable field-free switching of perpendicular magnetization through bulk spin-orbit torque in symmetry-broken ferromagnetic films. Nat Commun 2021; 12:2473. [PMID: 33931644 PMCID: PMC8087697 DOI: 10.1038/s41467-021-22819-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2020] [Accepted: 03/30/2021] [Indexed: 11/24/2022] Open
Abstract
Programmable magnetic field-free manipulation of perpendicular magnetization switching is essential for the development of ultralow-power spintronic devices. However, the magnetization in a centrosymmetric single-layer ferromagnetic film cannot be switched directly by passing an electrical current in itself. Here, we demonstrate a repeatable bulk spin-orbit torque (SOT) switching of the perpendicularly magnetized CoPt alloy single-layer films by introducing a composition gradient in the thickness direction to break the inversion symmetry. Experimental results reveal that the bulk SOT-induced effective field on the domain walls leads to the domain walls motion and magnetization switching. Moreover, magnetic field-free perpendicular magnetization switching caused by SOT and its switching polarity (clockwise or counterclockwise) can be reversibly controlled in the IrMn/Co/Ru/CoPt heterojunctions based on the exchange bias and interlayer exchange coupling. This unique composition gradient approach accompanied with electrically controllable SOT magnetization switching provides a promising strategy to access energy-efficient control of memory and logic devices. A major challenge of spintronics is achieving magnetic field free electrical control of magnetisation. Here, Xie et al. achieve perpendicular magnetisation switching in a CoPt alloy, breaking inversion symmetry by varying the composition of the alloy in the growth direction.
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Tang M, Shen K, Xu S, Yang H, Hu S, Lü W, Li C, Li M, Yuan Z, Pennycook SJ, Xia K, Manchon A, Zhou S, Qiu X. Bulk Spin Torque-Driven Perpendicular Magnetization Switching in L1 0 FePt Single Layer. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e2002607. [PMID: 32596934 DOI: 10.1002/adma.202002607] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 06/04/2020] [Indexed: 06/11/2023]
Abstract
Due to its inherent superior perpendicular magnetocrystalline anisotropy, the FePt in L10 phase enables magnetic storage and memory devices with ultrahigh capacity. However, reversing the FePt magnetic state, and therefore encoding information, has proven to be extremely difficult. Here, it is demonstrated that an electric current can exert a large spin torque on an L10 FePt magnet, ultimately leading to reversible magnetization switching. The spin torque monotonically increases with increasing FePt thickness, exhibiting a bulk characteristic. Meanwhile, the spin torque effective fields and switching efficiency increase as the FePt approaches higher chemical ordering with stronger spin-orbit coupling. The symmetry breaking that generates spin torque within L10 FePt is shown to arise from an inherent structural gradient along the film normal direction. By artificially reversing the structural gradient, an opposite spin torque effect in L10 FePt is demonstrated. At last, the role of the disorder gradient in generating a substantial torque in a single ferromagnet is supported by theoretical calculations. These results will push forward the frontier of material systems for generating spin torques and will have a transformative impact on magnetic storage and spin memory devices with simple architecture, ultrahigh density, and readily application.
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Affiliation(s)
- Meng Tang
- Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology School of Physics Science and Engineering, Tongji University, Shanghai, 200092, China
| | - Ka Shen
- Department of Physics, Beijing Normal University, Beijing, 100875, China
| | - Shijie Xu
- Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology School of Physics Science and Engineering, Tongji University, Shanghai, 200092, China
| | - Huanglin Yang
- Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology School of Physics Science and Engineering, Tongji University, Shanghai, 200092, China
| | - Shuai Hu
- Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology School of Physics Science and Engineering, Tongji University, Shanghai, 200092, China
| | - Weiming Lü
- Spintronics Institute, University of Jinan, Jinan, 250022, China
- Condensed Matter Science and Technology Institute, School of Science, Harbin Institute of Technology, Harbin, 150081, China
| | - Changjian Li
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Mengsha Li
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Zhe Yuan
- Department of Physics, Beijing Normal University, Beijing, 100875, China
| | - Stephen J Pennycook
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Ke Xia
- Beijing Computational Science Research Center, Beijing, 100193, China
| | - Aurelien Manchon
- Division of Physical Science and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955, Saudi Arabia
- Aix-Marseille Université, CNRS, CINaM, Marseille, 13288, France
| | - Shiming Zhou
- Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology School of Physics Science and Engineering, Tongji University, Shanghai, 200092, China
| | - Xuepeng Qiu
- Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology School of Physics Science and Engineering, Tongji University, Shanghai, 200092, China
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5
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Switching of multi-state magnetic structures via domain wall propagation triggered by spin-orbit torques. Sci Rep 2019; 9:20368. [PMID: 31889087 PMCID: PMC6937281 DOI: 10.1038/s41598-019-56714-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2019] [Accepted: 12/11/2019] [Indexed: 11/08/2022] Open
Abstract
Spin-orbit torques emerge as a promising method for manipulating magnetic configurations of spintronic devices. Here, we show that these torques can induce a magnetization reversal via domain wall propagation which may open new ways in developing novel spintronic devices and in particular in realizing high-density multi-level magnetic memory. Our devices are bi-layer heterostructures of Ni0.8Fe0.2 on top of β-Ta patterned in the form of two or three crossing ellipses which exhibit in the crossing area shape-induced biaxial and triaxial magnetic anisotropy, respectively. We demonstrate field-free switching between discrete remanent magnetic states of the structures by spin-orbit torques induced by flowing electrical current through one of the ellipses. We note switchings induced by the coupling between the ellipses where current flowing in one ellipse triggers a reversal in a neighboring ellipse which propagates from the center outwards. Numerical tools successfully simulate the observed coupling-induced switching using experimentally extracted parameters.
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Mishra R, Mahfouzi F, Kumar D, Cai K, Chen M, Qiu X, Kioussis N, Yang H. Electric-field control of spin accumulation direction for spin-orbit torques. Nat Commun 2019; 10:248. [PMID: 30651546 PMCID: PMC6335414 DOI: 10.1038/s41467-018-08274-8] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2018] [Accepted: 12/28/2018] [Indexed: 11/09/2022] Open
Abstract
Electric field is an energy-efficient tool that can be leveraged to control spin-orbit torques (SOTs). Although the amount of current-induced spin accumulation in a heavy metal (HM)/ferromagnet (FM) heterostructure can be regulated to a certain degree using an electric field in various materials, the control of its direction has remained elusive so far. Here, we report that both the direction and amount of current-induced spin accumulation at the HM/FM interface can be dynamically controlled using an electric field in an oxide capped SOT device. The applied electric field transports oxygen ions and modulates the HM/FM interfacial chemistry resulting in an interplay between the spin Hall and the interfacial torques which in turn facilitates a non-volatile and reversible control over the direction and magnitude of SOTs. Our electric-field controlled spin-orbitronics device can be programmed to behave either like the SOT systems with a positive spin Hall angle or a negative spin Hall angle.
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Affiliation(s)
- Rahul Mishra
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, 117576, Singapore
| | - Farzad Mahfouzi
- Department of Physics and Astronomy, California State University, Northridge, CA, 91330-8268, USA
| | - Dushyant Kumar
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, 117576, Singapore
| | - Kaiming Cai
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, 117576, Singapore
| | - Mengji Chen
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, 117576, Singapore
| | - Xuepeng Qiu
- Shanghai Key Laboratory of Special Artificial Microstructure Materials & School of Physics Science and Engineering, Tongji University, Shanghai, 200092, China
| | - Nicholas Kioussis
- Department of Physics and Astronomy, California State University, Northridge, CA, 91330-8268, USA
| | - Hyunsoo Yang
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, 117576, Singapore.
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7
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Yu J, Bang D, Mishra R, Ramaswamy R, Oh JH, Park HJ, Jeong Y, Van Thach P, Lee DK, Go G, Lee SW, Wang Y, Shi S, Qiu X, Awano H, Lee KJ, Yang H. Long spin coherence length and bulk-like spin-orbit torque in ferrimagnetic multilayers. NATURE MATERIALS 2019; 18:29-34. [PMID: 30510269 DOI: 10.1038/s41563-018-0236-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 10/23/2018] [Indexed: 06/09/2023]
Abstract
Spintronics relies on magnetization switching through current-induced spin torques. However, because spin transfer torque for ferromagnets is a surface torque, a large switching current is required for a thick, thermally stable ferromagnetic cell, and this remains a fundamental obstacle for high-density non-volatile applications with ferromagnets. Here, we report a long spin coherence length and associated bulk-like torque characteristics in an antiferromagnetically coupled ferrimagnetic multilayer. We find that a transverse spin current can pass through >10-nm-thick ferrimagnetic Co/Tb multilayers, whereas it is entirely absorbed by a 1-nm-thick ferromagnetic Co/Ni multilayer. We also find that the switching efficiency of Co/Tb multilayers partially reflects a bulk-like torque characteristic, as it increases with ferrimagnet thickness up to 8 nm and then decreases, in clear contrast to the 1/thickness dependence of ferromagnetic Co/Ni multilayers. Our results on antiferromagnetically coupled systems will invigorate research towards the development of energy-efficient spintronics.
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Affiliation(s)
- Jiawei Yu
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore
| | - Do Bang
- Toyota Technological Institute, Tempaku, Nagoya, Japan
- Institute of Materials Science, Vietnam Academy of Science and Technology, Hanoi, Vietnam
| | - Rahul Mishra
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore
| | - Rajagopalan Ramaswamy
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore
| | - Jung Hyun Oh
- Department of Materials Science and Engineering, Korea University, Seoul, Korea
| | - Hyeon-Jong Park
- KU-KIST Graduate School of Conversing Science and Technology, Korea University, Seoul, Korea
| | - Yunboo Jeong
- Department of Semiconductor Systems Engineering, Korea University, Seoul, Korea
| | - Pham Van Thach
- Toyota Technological Institute, Tempaku, Nagoya, Japan
- Institute of Materials Science, Vietnam Academy of Science and Technology, Hanoi, Vietnam
| | - Dong-Kyu Lee
- Department of Materials Science and Engineering, Korea University, Seoul, Korea
| | - Gyungchoon Go
- Department of Materials Science and Engineering, Korea University, Seoul, Korea
| | - Seo-Won Lee
- Department of Materials Science and Engineering, Korea University, Seoul, Korea
| | - Yi Wang
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore
| | - Shuyuan Shi
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore
| | - Xuepeng Qiu
- Shanghai Key Laboratory of Special Artificial Macrostructure Materials and Technology and School of Physics Science and Engineering, Tongji University, Shanghai, China
| | | | - Kyung-Jin Lee
- Department of Materials Science and Engineering, Korea University, Seoul, Korea.
- KU-KIST Graduate School of Conversing Science and Technology, Korea University, Seoul, Korea.
- Department of Semiconductor Systems Engineering, Korea University, Seoul, Korea.
| | - Hyunsoo Yang
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, Singapore.
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8
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Moon KW, Kim C, Yoon J, Choi JW, Kim DO, Song KM, Kim D, Chun BS, Hwang C. A spin torque meter with magnetic facet domains. Nat Commun 2018; 9:3788. [PMID: 30224700 PMCID: PMC6141574 DOI: 10.1038/s41467-018-06223-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Accepted: 08/24/2018] [Indexed: 11/23/2022] Open
Abstract
Current-induced magnetic domain wall (DW) motion is an important operating principle of spintronic devices. Injected current generates spin torques (STs) on the DWs in two ways. One is the spin transfer from magnetic domains to the walls by the current flowing in the magnet. Current flow in attached heavy metals also generates another ST because of the spin-Hall effect. Both phenomena explain the wall motions well; therefore, their respective contribution is an important issue. Here, we show the simultaneous measurement of both torques by using magnetic facet domains that form mountain-shaped domains with straight walls. When the STs and the external magnetic field push the walls in opposite directions, the walls should have equilibrium angles to create balanced states. Such angles can be modulated by an additional in-plane magnetic field. Angle measurements distinguish the STs because each torque has a distinct mechanism related to the DW structure.
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Affiliation(s)
- Kyoung-Woong Moon
- Spin Convergence Research Team, Korea Research Institute of Standards and Science, Daejeon, 34113, Republic of Korea
| | - Changsoo Kim
- Spin Convergence Research Team, Korea Research Institute of Standards and Science, Daejeon, 34113, Republic of Korea
| | - Jungbum Yoon
- Spin Convergence Research Team, Korea Research Institute of Standards and Science, Daejeon, 34113, Republic of Korea
| | - Jun Woo Choi
- Center for Spintronics, Korea Institute of Science and Technology, Seoul, 02792, Republic of Korea
| | - Dong-Ok Kim
- Center for Spintronics, Korea Institute of Science and Technology, Seoul, 02792, Republic of Korea
- Department of Physics, Soongsil University, Seoul, 06978, Republic of Korea
| | - Kyung Mee Song
- Center for Spintronics, Korea Institute of Science and Technology, Seoul, 02792, Republic of Korea
- Department of Physics, Sookmyung Women's University, Seoul, 04130, Republic of Korea
| | - Dongseuk Kim
- Spin Convergence Research Team, Korea Research Institute of Standards and Science, Daejeon, 34113, Republic of Korea
| | - Byong Sun Chun
- Spin Convergence Research Team, Korea Research Institute of Standards and Science, Daejeon, 34113, Republic of Korea
| | - Chanyong Hwang
- Spin Convergence Research Team, Korea Research Institute of Standards and Science, Daejeon, 34113, Republic of Korea.
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Anatomy of interfacial spin-orbit coupling in Co/Pd multilayers using X-ray magnetic circular dichroism and first-principles calculations. Sci Rep 2018; 8:8303. [PMID: 29844428 PMCID: PMC5974019 DOI: 10.1038/s41598-018-26195-w] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Accepted: 05/04/2018] [Indexed: 11/08/2022] Open
Abstract
Element-specific orbital magnetic moments and their anisotropies in perpendicularly magnetised Co/Pd multilayers are investigated using Co L-edge and Pd M-edge angle-dependent x-ray magnetic circular dichroism. We show that the orbital magnetic moments in Co are anisotropic, whereas those in Pd are isotropic. The first-principles density-functional-theory calculations also suggest that the Co/Pd interfacial orbital magnetic moments in Co are anisotropic and contribute to the perpendicular magnetic anisotropy (PMA), and that the isotropic ones in Pd manipulates the Co orbitals at the interface through proximity effects. Orbital-resolved anatomy of Co/Pd interfaces reveals that the orbital moment anisotropy in Co and spin-flipped transition related to the magnetic dipoles in Pd are essential for the appearance of PMA.
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Tang M, Zhao B, Zhu W, Zhu Z, Jin QY, Zhang Z. Controllable Interfacial Coupling Effects on the Magnetic Dynamic Properties of Perpendicular [Co/Ni] 5/Cu/TbCo Composite Thin Films. ACS APPLIED MATERIALS & INTERFACES 2018; 10:5090-5098. [PMID: 29328631 DOI: 10.1021/acsami.7b16978] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
Dynamic magnetic properties in perpendicularly exchange-coupled [Co/Ni]5/Cu (tCu = 0-2 nm)/TbCo structures show strong dependences on the interfacial antiferromagnetic strength Jex, which is controlled by the Cu interlayer thickness. The precession frequency f and effective damping constant αeff of a [Co/Ni]5 multilayer differ distinctly for parallel (P) and antiparallel (AP) magnetization orientation states. For samples with a thin tCu, f of the AP state is apparently higher, whereas αeff is lower than that in the P state, owing to the unidirectional exchange bias effect (HEB) from the TbCo layer. The differences in f and αeff between the two states gradually decrease with increasing tCu. By using a uniform precession model including an additional HEB term, the field-dependent frequency curves can be well-fitted, and the fitted HEB value is in good agreement with the experimental data. Moreover, the saturation damping constant α0 displays a nearly linear correlation with Jex. It decreases significantly with Jex and eventually approaches a constant value of 0.027 at tCu = 2 nm where Jex vanishes. These results provide a better understanding and effective control of magnetization dynamics in exchange-coupled composite structures for spintronic applications.
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Affiliation(s)
- Minghong Tang
- Department of Optical Science and Engineering, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), and Shanghai Ultra-Precision Optical Manufacturing Engineering Center, Fudan University , Shanghai 200433, China
| | - Bingcheng Zhao
- Department of Optical Science and Engineering, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), and Shanghai Ultra-Precision Optical Manufacturing Engineering Center, Fudan University , Shanghai 200433, China
| | - Weihua Zhu
- Department of Optical Science and Engineering, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), and Shanghai Ultra-Precision Optical Manufacturing Engineering Center, Fudan University , Shanghai 200433, China
| | - Zhendong Zhu
- Department of Optical Science and Engineering, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), and Shanghai Ultra-Precision Optical Manufacturing Engineering Center, Fudan University , Shanghai 200433, China
| | - Q Y Jin
- Department of Optical Science and Engineering, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), and Shanghai Ultra-Precision Optical Manufacturing Engineering Center, Fudan University , Shanghai 200433, China
| | - Zongzhi Zhang
- Department of Optical Science and Engineering, Key Laboratory of Micro and Nano Photonic Structures (Ministry of Education), and Shanghai Ultra-Precision Optical Manufacturing Engineering Center, Fudan University , Shanghai 200433, China
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11
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Cui B, Li D, Yun J, Zuo Y, Guo X, Wu K, Zhang X, Wang Y, Xi L, Xue D. Magnetization switching through domain wall motion in Pt/Co/Cr racetracks with the assistance of the accompanying Joule heating effect. Phys Chem Chem Phys 2018; 20:9904-9909. [DOI: 10.1039/c7cp08352a] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Heavy metal/ferromagnetic layers with perpendicular magnetic anisotropy (PMA) have potential applications for high-density information storage in racetrack memories and nonvolatile magnetic random access memories.
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Affiliation(s)
- Baoshan Cui
- Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education & School of Physical Science and Technology
- Lanzhou University
- P. R. China
| | - Dong Li
- Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education & School of Physical Science and Technology
- Lanzhou University
- P. R. China
| | - Jijun Yun
- Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education & School of Physical Science and Technology
- Lanzhou University
- P. R. China
| | - Yalu Zuo
- Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education & School of Physical Science and Technology
- Lanzhou University
- P. R. China
| | - Xiaobin Guo
- Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education & School of Physical Science and Technology
- Lanzhou University
- P. R. China
| | - Kai Wu
- Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education & School of Physical Science and Technology
- Lanzhou University
- P. R. China
| | - Xu Zhang
- Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education & School of Physical Science and Technology
- Lanzhou University
- P. R. China
| | - Yupei Wang
- Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education & School of Physical Science and Technology
- Lanzhou University
- P. R. China
| | - Li Xi
- Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education & School of Physical Science and Technology
- Lanzhou University
- P. R. China
| | - Desheng Xue
- Key Laboratory for Magnetism and Magnetic Materials of Ministry of Education & School of Physical Science and Technology
- Lanzhou University
- P. R. China
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12
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The interfacial nature of proximity-induced magnetism and the Dzyaloshinskii-Moriya interaction at the Pt/Co interface. Sci Rep 2017; 7:16835. [PMID: 29203797 PMCID: PMC5715054 DOI: 10.1038/s41598-017-17137-z] [Citation(s) in RCA: 55] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2017] [Accepted: 11/22/2017] [Indexed: 11/08/2022] Open
Abstract
The Dzyaloshinskii-Moriya interaction has been shown to stabilise Nèel domain walls in magnetic thin films, allowing high domain wall velocities driven by spin current effects. The interfacial Dzyaloshinskii-Moriya interaction (IDMI) occurs at the interface between ferromagnetic and heavy metal layers with strong spin-orbit coupling, but details of the interaction remain to be understood and the role of proximity induced magnetism (PIM) in the heavy metal is unknown. Here IDMI and PIM are reported in Pt determined as a function of Au and Ir spacer layers in Pt/Co/Au,Ir/Pt. Both interactions are found to be sensitive to sub-nanometre changes in the spacer thickness, correlating over sub-monolayer spacer thicknesses, but not for thicker spacers where IDMI continues to change even after PIM is lost.
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13
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Mishra R, Yu J, Qiu X, Motapothula M, Venkatesan T, Yang H. Anomalous Current-Induced Spin Torques in Ferrimagnets near Compensation. PHYSICAL REVIEW LETTERS 2017; 118:167201. [PMID: 28474947 DOI: 10.1103/physrevlett.118.167201] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/23/2016] [Indexed: 06/07/2023]
Abstract
While current-induced spin-orbit torques have been extensively studied in ferromagnets and antiferromagnets, ferrimagnets have been less studied. Here we report the presence of enhanced spin-orbit torques resulting from negative exchange interaction in ferrimagnets. The effective field and switching efficiency increase substantially as CoGd approaches its compensation point, giving rise to 9 times larger spin-orbit torques compared to that of a noncompensated one. The macrospin modeling results also support efficient spin-orbit torques in a ferrimagnet. Our results suggest that ferrimagnets near compensation can be a new route for spin-orbit torque applications due to their high thermal stability and easy current-induced switching assisted by negative exchange interaction.
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Affiliation(s)
- Rahul Mishra
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Singapore
| | - Jiawei Yu
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Singapore
| | - Xuepeng Qiu
- Shanghai Key Laboratory of Special Artificial Microstructure Materials & School of Physics Science and Engineering, Tongji University, Shanghai 200092, China
| | - M Motapothula
- NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
| | - T Venkatesan
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Singapore
- NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
- Department of Physics, National University of Singapore, Singapore 117542, Singapore
- Department of Materials Science and Engineering, National University of Singapore, Singapore 117542, Singapore
- Integrated Science and Engineering Department, National University of Singapore, Singapore 117542, Singapore
| | - Hyunsoo Yang
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Singapore
- NUSNNI-NanoCore, National University of Singapore, Singapore 117411, Singapore
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14
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Yoon J, Lee SW, Kwon JH, Lee JM, Son J, Qiu X, Lee KJ, Yang H. Anomalous spin-orbit torque switching due to field-like torque-assisted domain wall reflection. SCIENCE ADVANCES 2017; 3:e1603099. [PMID: 28439562 PMCID: PMC5400426 DOI: 10.1126/sciadv.1603099] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2016] [Accepted: 02/17/2017] [Indexed: 05/30/2023]
Abstract
Spin-orbit torques (SOTs) allow the electrical control of magnetic states. Current-induced SOT switching of the perpendicular magnetization is of particular technological importance. The SOT consists of damping-like and field-like torques, and understanding the combined effects of these two torque components is required for efficient SOT switching. Previous quasi-static measurements have reported an increased switching probability with the width of current pulses, as predicted considering the damping-like torque alone. We report a decreased switching probability at longer pulse widths, based on time-resolved measurements. Micromagnetic analysis reveals that this anomalous SOT switching results from domain wall reflections at sample edges. The domain wall reflection was found to strongly depend on the field-like torque and its relative sign to the damping-like torque. Our result demonstrates a key role of the field-like torque in deterministic SOT switching and the importance of the sign correlation of the two torque components, which may shed light on the SOT switching mechanism.
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Affiliation(s)
- Jungbum Yoon
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Singapore
| | - Seo-Won Lee
- Department of Materials Science and Engineering, Korea University, Seoul 02841, Republic of Korea
| | - Jae Hyun Kwon
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Singapore
| | - Jong Min Lee
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Singapore
| | - Jaesung Son
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Singapore
| | - Xuepeng Qiu
- Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology, School of Physics Science and Engineering, Tongji University, Shanghai 200092, China
| | - Kyung-Jin Lee
- Department of Materials Science and Engineering, Korea University, Seoul 02841, Republic of Korea
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 02841, Republic of Korea
| | - Hyunsoo Yang
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore 117576, Singapore
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15
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Hellman F, Hoffmann A, Tserkovnyak Y, Beach GSD, Fullerton EE, Leighton C, MacDonald AH, Ralph DC, Arena DA, Dürr HA, Fischer P, Grollier J, Heremans JP, Jungwirth T, Kimel AV, Koopmans B, Krivorotov IN, May SJ, Petford-Long AK, Rondinelli JM, Samarth N, Schuller IK, Slavin AN, Stiles MD, Tchernyshyov O, Thiaville A, Zink BL. Interface-Induced Phenomena in Magnetism. REVIEWS OF MODERN PHYSICS 2017; 89:025006. [PMID: 28890576 PMCID: PMC5587142 DOI: 10.1103/revmodphys.89.025006] [Citation(s) in RCA: 192] [Impact Index Per Article: 27.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
This article reviews static and dynamic interfacial effects in magnetism, focusing on interfacially-driven magnetic effects and phenomena associated with spin-orbit coupling and intrinsic symmetry breaking at interfaces. It provides a historical background and literature survey, but focuses on recent progress, identifying the most exciting new scientific results and pointing to promising future research directions. It starts with an introduction and overview of how basic magnetic properties are affected by interfaces, then turns to a discussion of charge and spin transport through and near interfaces and how these can be used to control the properties of the magnetic layer. Important concepts include spin accumulation, spin currents, spin transfer torque, and spin pumping. An overview is provided to the current state of knowledge and existing review literature on interfacial effects such as exchange bias, exchange spring magnets, spin Hall effect, oxide heterostructures, and topological insulators. The article highlights recent discoveries of interface-induced magnetism and non-collinear spin textures, non-linear dynamics including spin torque transfer and magnetization reversal induced by interfaces, and interfacial effects in ultrafast magnetization processes.
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Affiliation(s)
- Frances Hellman
- Department of Physics, University of California, Berkeley, Berkeley, California 94720, USA; Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA
| | - Axel Hoffmann
- Materials Science Division, Argonne National Laboratory, Argonne, Illinois 60439, USA
| | - Yaroslav Tserkovnyak
- Department of Physics and Astronomy, University of California, Los Angeles, California 90095, USA
| | - Geoffrey S D Beach
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Eric E Fullerton
- Center for Memory and Recording Research, University of California, San Diego, 9500 Gilman Drive, La Jolla, California 92093-0401, USA
| | - Chris Leighton
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, USA
| | - Allan H MacDonald
- Department of Physics, University of Texas at Austin, Austin, Texas 78712-0264, USA
| | - Daniel C Ralph
- Physics Department, Cornell University, Ithaca, New York 14853, USA; Kavli Institute at Cornell, Cornell University, Ithaca, New York 14853, USA
| | - Dario A Arena
- Department of Physics, University of South Florida, Tampa, Florida 33620-7100, USA
| | - Hermann A Dürr
- Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, USA
| | - Peter Fischer
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA; Physics Department, University of California, 1156 High Street, Santa Cruz, California 94056, USA
| | - Julie Grollier
- Unité Mixte de Physique CNRS/Thales and Université Paris Sud 11, 1 Avenue Fresnel, 91767 Palaiseau, France
| | - Joseph P Heremans
- Department of Mechanical and Aerospace Engineering, The Ohio State University, Columbus, Ohio 43210, USA; Department of Materials Science and Engineering, The Ohio State University, Columbus, Ohio 43210, USA; Department of Physics, The Ohio State University, Columbus, Ohio 43210, USA
| | - Tomas Jungwirth
- Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnicka 10, 162 53 Praha 6, Czech Republic; School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD, United Kingdom
| | - Alexey V Kimel
- Radboud University, Institute for Molecules and Materials, Nijmegen 6525 AJ, The Netherlands
| | - Bert Koopmans
- Department of Applied Physics, Center for NanoMaterials, COBRA Research Institute, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands
| | - Ilya N Krivorotov
- Department of Physics and Astronomy, University of California, Irvine, California 92697, USA
| | - Steven J May
- Department of Materials Science & Engineering, Drexel University, Philadelphia, Pennsylvania 19104, USA
| | - Amanda K Petford-Long
- Materials Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439, USA; Department of Materials Science and Engineering, Northwestern University, 2220 Campus Drive, Evanston, Illinois 60208, USA
| | - James M Rondinelli
- Department of Materials Science and Engineering, Northwestern University, Evanston, Illinois 60208, USA
| | - Nitin Samarth
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
| | - Ivan K Schuller
- Department of Physics and Center for Advanced Nanoscience, University of California, San Diego, La Jolla, California 92093, USA; Materials Science and Engineering Program, University of California, San Diego, La Jolla, California 92093, USA
| | - Andrei N Slavin
- Department of Physics, Oakland University, Rochester, Michigan 48309, USA
| | - Mark D Stiles
- Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6202, USA
| | - Oleg Tchernyshyov
- Department of Physics and Astronomy, The Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - André Thiaville
- Laboratoire de Physique des Solides, UMR CNRS 8502, Université Paris-Sud, 91405 Orsay, France
| | - Barry L Zink
- Department of Physics and Astronomy, University of Denver, Denver, CO 80208, USA
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16
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Observation of stable Néel skyrmions in cobalt/palladium multilayers with Lorentz transmission electron microscopy. Nat Commun 2017; 8:14761. [PMID: 28281542 PMCID: PMC5353624 DOI: 10.1038/ncomms14761] [Citation(s) in RCA: 68] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2016] [Accepted: 01/30/2017] [Indexed: 11/16/2022] Open
Abstract
Néel skyrmions are of high interest due to their potential applications in a variety of spintronic devices, currently accessible in ultrathin heavy metal/ferromagnetic bilayers and multilayers with a strong Dzyaloshinskii–Moriya interaction. Here we report on the direct imaging of chiral spin structures including skyrmions in an exchange-coupled cobalt/palladium multilayer at room temperature with Lorentz transmission electron microscopy, a high-resolution technique previously suggested to exhibit no Néel skyrmion contrast. Phase retrieval methods allow us to map the internal spin structure of the skyrmion core, identifying a 25 nm central region of uniform magnetization followed by a larger region characterized by rotation from in- to out-of-plane. The formation and resolution of the internal spin structure of room temperature skyrmions without a stabilizing out-of-plane field in thick magnetic multilayers opens up a new set of tools and materials to study the physics and device applications associated with chiral ordering and skyrmions. Néel skyrmions are spin textures with a magnetization that rotates from in- to out-of-plane with distance from its centre. Here, the authors show that Lorentz transmission electron microscopy can be used to directly image Néel skyrmions with high resolution in thick exchange-coupled magnetic multilayers.
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17
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Huang KF, Wang DS, Tsai MH, Lin HH, Lai CH. Initialization-Free Multilevel States Driven by Spin-Orbit Torque Switching. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2017; 29:1601575. [PMID: 28097688 DOI: 10.1002/adma.201601575] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2016] [Revised: 10/04/2016] [Indexed: 06/06/2023]
Abstract
By engineering multidomain formation in Co/Pt multilayers, it is demonstrated how multilevel storage can be achieved by spin-orbit torque switching. It is rather remarkable that, by modulating the writing pulse conditions, the final magnetization states can be controlled, independent of the initial configurations. The initialization-free multilevel memory advances the spin-orbit-torque magnetic random access memory to higher storage density for practical applications.
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Affiliation(s)
- Kuo-Feng Huang
- Department of Materials Science and Engineering, National Tsing Hua University, No. 101, Section 2, Kuang-Fu Road, Hsinchu, Taiwan, 30013, ROC
| | - Ding-Shuo Wang
- Department of Materials Science and Engineering, National Tsing Hua University, No. 101, Section 2, Kuang-Fu Road, Hsinchu, Taiwan, 30013, ROC
| | - Ming-Han Tsai
- Department of Materials Science and Engineering, National Tsing Hua University, No. 101, Section 2, Kuang-Fu Road, Hsinchu, Taiwan, 30013, ROC
| | - Hsiu-Hau Lin
- Department of Physics, National Tsing Hua University, No. 101, Section 2, Kuang-Fu Road, Hsinchu, Taiwan, 30013, ROC
| | - Chih-Huang Lai
- Department of Materials Science and Engineering, National Tsing Hua University, No. 101, Section 2, Kuang-Fu Road, Hsinchu, Taiwan, 30013, ROC
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18
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Qiu X, Legrand W, He P, Wu Y, Yu J, Ramaswamy R, Manchon A, Yang H. Enhanced Spin-Orbit Torque via Modulation of Spin Current Absorption. PHYSICAL REVIEW LETTERS 2016; 117:217206. [PMID: 27911535 DOI: 10.1103/physrevlett.117.217206] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/28/2016] [Indexed: 06/06/2023]
Abstract
The magnitude of spin-orbit torque (SOT), exerted to a ferromagnet (FM) from an adjacent heavy metal (HM), strongly depends on the amount of spin current absorbed in the FM. We exploit the large spin absorption at the Ru interface to manipulate the SOTs in HM/FM/Ru multilayers. While the FM thickness is smaller than its spin dephasing length of 1.2 nm, the top Ru layer largely boosts the absorption of spin currents into the FM layer and substantially enhances the strength of SOT acting on the FM. Spin-pumping experiments induced by ferromagnetic resonance support our conclusions that the observed increase in the SOT efficiency can be attributed to an enhancement of the spin-current absorption. A theoretical model that considers both reflected and transmitted mixing conductances at the two interfaces of FM is developed to explain the results.
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Affiliation(s)
- Xuepeng Qiu
- Department of Electrical and Computer Engineering, and NUSNNI, National University of Singapore, Singapore 117576, Singapore
- Shanghai Key Laboratory of Special Artificial Microstructure Materials & School of Physics Science and Engineering, Tongji University, Shanghai 200092, China
| | - William Legrand
- Department of Electrical and Computer Engineering, and NUSNNI, National University of Singapore, Singapore 117576, Singapore
| | - Pan He
- Department of Electrical and Computer Engineering, and NUSNNI, National University of Singapore, Singapore 117576, Singapore
| | - Yang Wu
- Department of Electrical and Computer Engineering, and NUSNNI, National University of Singapore, Singapore 117576, Singapore
| | - Jiawei Yu
- Department of Electrical and Computer Engineering, and NUSNNI, National University of Singapore, Singapore 117576, Singapore
| | - Rajagopalan Ramaswamy
- Department of Electrical and Computer Engineering, and NUSNNI, National University of Singapore, Singapore 117576, Singapore
| | - Aurelien Manchon
- Division of Physical Science and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal 23955, Saudi Arabia
| | - Hyunsoo Yang
- Department of Electrical and Computer Engineering, and NUSNNI, National University of Singapore, Singapore 117576, Singapore
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19
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Spin orbit torques and Dzyaloshinskii-Moriya interaction in dual-interfaced Co-Ni multilayers. Sci Rep 2016; 6:32629. [PMID: 27601317 PMCID: PMC5013523 DOI: 10.1038/srep32629] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2016] [Accepted: 08/11/2016] [Indexed: 11/12/2022] Open
Abstract
We study the spin orbit torque (SOT) and Dzyaloshinskii-Moriya interaction (DMI) in the dual-interfaced Co-Ni perpendicular multilayers. Through the combination of top and bottom layer materials (Pt, Ta, MgO and Cu), SOT and DMI are efficiently manipulated due to an enhancement or cancellation of the top and bottom contributions. However, SOT is found to originate mostly from the bulk of a heavy metal (HM), while DMI is more of interfacial origin. In addition, we find that the direction of the domain wall (DW) motion can be either along or against the electron flow depending on the DW tilting angle when there is a large DMI. Such an abnormal DW motion induces a large assist field required for hysteretic magnetization reversal. Our results provide insight into the role of DMI in SOT driven magnetization switching, and demonstrate the feasibility of achieving desirable SOT and DMI for spintronic devices.
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20
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Self-current induced spin-orbit torque in FeMn/Pt multilayers. Sci Rep 2016; 6:26180. [PMID: 27185656 PMCID: PMC4868966 DOI: 10.1038/srep26180] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2016] [Accepted: 04/27/2016] [Indexed: 11/25/2022] Open
Abstract
Extensive efforts have been devoted to the study of spin-orbit torque in
ferromagnetic metal/heavy metal bilayers and exploitation of it for magnetization
switching using an in-plane current. As the spin-orbit torque is inversely
proportional to the thickness of the ferromagnetic layer, sizable effect has only
been realized in bilayers with an ultrathin ferromagnetic layer. Here we demonstrate
that, by stacking ultrathin Pt and FeMn alternately, both ferromagnetic properties
and current induced spin-orbit torque can be achieved in FeMn/Pt multilayers without
any constraint on its total thickness. The critical behavior of these multilayers
follows closely three-dimensional Heisenberg model with a finite Curie temperature
distribution. The spin torque effective field is about 4 times larger than that of
NiFe/Pt bilayer with a same equivalent NiFe thickness. The self-current generated
spin torque is able to switch the magnetization reversibly without the need for an
external field or a thick heavy metal layer. The removal of both thickness
constraint and necessity of using an adjacent heavy metal layer opens new
possibilities for exploiting spin-orbit torque for practical applications.
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21
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Asymmetric magnetic proximity effect in a Pd/Co/Pd trilayer system. Sci Rep 2016; 6:25391. [PMID: 27151368 PMCID: PMC4858727 DOI: 10.1038/srep25391] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2016] [Accepted: 04/15/2016] [Indexed: 11/08/2022] Open
Abstract
In spintronic devices consisting of ferromagnetic/nonmagnetic systems, the ferromagnet-induced magnetic moment in the adjacent nonmagnetic material significantly influences the spin transport properties. In this study, such magnetic proximity effect in a Pd/Co/Pd trilayer system is investigated by x-ray magnetic circular dichroism and x-ray resonant magnetic reflectivity, which enables magnetic characterizations with element and depth resolution. We observe that the total Pd magnetic moments induced at the top Co/Pd interface are significantly larger than the Pd moments at the bottom Pd/Co interface, whereas transmission electron microscopy and reflectivity analysis indicate the two interfaces are nearly identical structurally. Such asymmetry in magnetic proximity effects could be important for understanding spin transport characteristics in ferromagnetic/nonmagnetic systems and its potential application to spin devices.
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22
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Grytsyuk S, Belabbes A, Haney PM, Lee HW, Lee KJ, Stiles MD, Schwingenschögl U, Manchon A. k-asymmetric spin-splitting at the interface between transition metal ferromagnets and heavy metals. PHYSICAL REVIEW. B 2016; 93:174421. [PMID: 27441303 PMCID: PMC4939709 DOI: 10.1103/physrevb.93.174421] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We systematically investigate the spin-orbit coupling-induced band splitting originating from inversion symmetry breaking at the interface between a Co monolayer and 4d (Tc, Ru, Rh, Pd, and Ag) or 5d (Re, Os, Ir, Pt, and Au) transition metals. In spite of the complex band structure of these systems, the odd-in-k spin splitting of the bands displays striking similarities with the much simpler Rashba spin-orbit coupling picture. While we do not find salient correlations between the interfacial magnetic anisotropy and the odd-in-k spin-splitting of the bands, we establish a clear connection between the overall strength of the band splitting and the charge transfer between the d-orbitals at the interface. Furthermore, we show that the spin splitting of the Fermi surface scales with the induced orbital moment, weighted by the spin-orbit coupling.
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Affiliation(s)
- Sergiy Grytsyuk
- Physical Science and Engineering Division, KAUST, 23955-6900 Thuwal, Kingdom of Saudi Arabia
| | - Abderrezak Belabbes
- Physical Science and Engineering Division, KAUST, 23955-6900 Thuwal, Kingdom of Saudi Arabia
| | - Paul M. Haney
- Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6202, USA
| | - Hyun-Woo Lee
- PCTP and Department of Physics, Pohang University of Science and Technology, Kyungbuk 790-784, Korea
| | - Kyung-Jin Lee
- Department of Materials Science and Engineering, Korea University, Seoul 136-713, South Korea
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 136-713, Korea
| | - M. D. Stiles
- Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, Maryland 20899-6202, USA
| | - Udo Schwingenschögl
- Physical Science and Engineering Division, KAUST, 23955-6900 Thuwal, Kingdom of Saudi Arabia
| | - Aurelien Manchon
- Physical Science and Engineering Division, KAUST, 23955-6900 Thuwal, Kingdom of Saudi Arabia
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23
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Choi YH, Yoshimura Y, Kim KJ, Lee K, Kim TW, Ono T, You CY, Jung MH. Field-driven domain wall motion under a bias current in the creep and flow regimes in Pt/[CoSiB/Pt]N nanowires. Sci Rep 2016; 6:23933. [PMID: 27030379 PMCID: PMC4814914 DOI: 10.1038/srep23933] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2015] [Accepted: 03/16/2016] [Indexed: 11/09/2022] Open
Abstract
The dynamics of magnetic domain wall (DW) in perpendicular magnetic anisotropy Pt/[CoSiB/Pt]N nanowires was studied by measuring the DW velocity under a magnetic field (H) and an electric current (J) in two extreme regimes of DW creep and flow. Two important findings are addressed. One is that the field-driven DW velocity increases with increasing N in the flow regime, whereas the trend is inverted in the creep regime. The other is that the sign of spin current-induced effective field is gradually reversed with increasing N in both DW creep and flow regimes. To reveal the underlying mechanism of new findings, we performed further experiment and micromagnetic simulation, from which we found that the observed phenomena can be explained by the combined effect of the DW anisotropy, Dzyaloshinskii-Moriya interaction, spin-Hall effect, and spin-transfer torques. Our results shed light on the mechanism of DW dynamics in novel amorphous PMA nanowires, so that this work may open a path to utilize the amorphous PMA in emerging DW-based spintronic devices.
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Affiliation(s)
- Y H Choi
- Department of Physics, Sogang University, Seoul 121-742 Korea
| | - Y Yoshimura
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - K-J Kim
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - K Lee
- Institute of Physics, Johannes Gutenberg-Universität Mainz, 55128 Mainz, Germany
| | - T W Kim
- Department of Advanced Materials Engineering, Sejong University, Seoul 143-747 Korea
| | - T Ono
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - C-Y You
- Department of Physics, Inha University, Incheon 402-751, Korea
| | - M H Jung
- Department of Physics, Sogang University, Seoul 121-742 Korea
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24
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Prenat G, Garello K, Langer J, Ocker B, Cyrille MC, Gambardella P, Tahoori M, Gaudin G, Jabeur K, Vanhauwaert P, Pendina GD, Oboril F, Bishnoi R, Ebrahimi M, Lamard N, Boulle O. Ultra-Fast and High-Reliability SOT-MRAM: From Cache Replacement to Normally-Off Computing. ACTA ACUST UNITED AC 2016. [DOI: 10.1109/tmscs.2015.2509963] [Citation(s) in RCA: 106] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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25
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Qiu X, Narayanapillai K, Wu Y, Deorani P, Yang DH, Noh WS, Park JH, Lee KJ, Lee HW, Yang H. Spin-orbit-torque engineering via oxygen manipulation. NATURE NANOTECHNOLOGY 2015; 10:333-338. [PMID: 25730601 DOI: 10.1038/nnano.2015.18] [Citation(s) in RCA: 75] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/03/2013] [Accepted: 01/20/2015] [Indexed: 06/04/2023]
Abstract
Spin transfer torques allow the electrical manipulation of magnetization at room temperature, which is desirable in spintronic devices such as spin transfer torque memories. When combined with spin-orbit coupling, they give rise to spin-orbit torques, which are a more powerful tool for controlling magnetization and can enrich device functionalities. The engineering of spin-orbit torques, based mostly on the spin Hall effect, is being intensely pursued. Here, we report that the oxidation of spin-orbit-torque devices triggers a new mechanism of spin-orbit torque, which is about two times stronger than that based on the spin Hall effect. We thus introduce a way to engineer spin-orbit torques via oxygen manipulation. Combined with electrical gating of the oxygen level, our findings may also pave the way towards reconfigurable logic devices.
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Affiliation(s)
- Xuepeng Qiu
- Department of Electrical and Computer Engineering, and NUSNNI-Nanocore, National University of Singapore, Singapore 117576, Singapore
| | - Kulothungasagaran Narayanapillai
- Department of Electrical and Computer Engineering, and NUSNNI-Nanocore, National University of Singapore, Singapore 117576, Singapore
| | - Yang Wu
- Department of Electrical and Computer Engineering, and NUSNNI-Nanocore, National University of Singapore, Singapore 117576, Singapore
| | - Praveen Deorani
- Department of Electrical and Computer Engineering, and NUSNNI-Nanocore, National University of Singapore, Singapore 117576, Singapore
| | - Dong-Hyuk Yang
- c_CCMR and Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Woo-Suk Noh
- c_CCMR and Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Jae-Hoon Park
- 1] c_CCMR and Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea [2] Division of Advanced Materials Science, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Kyung-Jin Lee
- 1] Department of Materials Science and Engineering, Korea University, Seoul 136-701, Korea [2] KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 136-713, Korea
| | - Hyun-Woo Lee
- PCTP and Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea
| | - Hyunsoo Yang
- Department of Electrical and Computer Engineering, and NUSNNI-Nanocore, National University of Singapore, Singapore 117576, Singapore
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26
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Saravanan K, Kao CH, Shao YC, Wang YF, Wang BY, Wang HT, Tsai CJ, Lin WC, Pao CW, Tsai HM, Jang LY, Lin HJ, Lee JF, Pong WF. Magnetic anisotropic properties of Pd/Co/Pd trilayer films studied by X-ray absorption spectroscopy and magnetic circular dichroism. RSC Adv 2015. [DOI: 10.1039/c4ra15683h] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Strong perpendicular magnetic anisotropy (PMA) is observed in annealed Pd/Co/Pd trilayer film. The effect of temperature on alloy formation, the relationship among the atomic/electronic structures, magnetic moments and PMA has been studied.
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27
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Lee HR, Lee K, Cho J, Choi YH, You CY, Jung MH, Bonell F, Shiota Y, Miwa S, Suzuki Y. Spin-orbit torque in a bulk perpendicular magnetic anisotropy Pd/FePd/MgO system. Sci Rep 2014; 4:6548. [PMID: 25293693 PMCID: PMC4189023 DOI: 10.1038/srep06548] [Citation(s) in RCA: 55] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2014] [Accepted: 09/17/2014] [Indexed: 11/28/2022] Open
Abstract
Spin-orbit torques, including the Rashba and spin Hall effects, have been widely observed and investigated in various systems. Since interesting spin-orbit torque (SOT) arises at the interface between heavy nonmagnetic metals and ferromagnetic metals, most studies have focused on the ultra-thin ferromagnetic layer with interface perpendicular magnetic anisotropy. Here, we measured the effective longitudinal and transverse fields of bulk perpendicular magnetic anisotropy Pd/FePd (1.54 to 2.43 nm)/MgO systems using harmonic methods with careful correction procedures. We found that in our range of thicknesses, the effective longitudinal and transverse fields are five to ten times larger than those reported in interface perpendicular magnetic anisotropy systems. The observed magnitude and thickness dependence of the effective fields suggest that the SOT do not have a purely interfacial origin in our samples.
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Affiliation(s)
- Hwang-Rae Lee
- Department of Physics, Inha University, Incheon 402-751, Korea
| | - Kyujoon Lee
- Department of Physics, Sogang University, Seoul 121-742, Korea
| | - Jaehun Cho
- Department of Physics, Inha University, Incheon 402-751, Korea
| | - Young-Ha Choi
- Department of Physics, Sogang University, Seoul 121-742, Korea
| | - Chun-Yeol You
- Department of Physics, Inha University, Incheon 402-751, Korea
| | - Myung-Hwa Jung
- Department of Physics, Sogang University, Seoul 121-742, Korea
| | - Frédéric Bonell
- 1] Graduate School of Engineering Science, Osaka University, Osaka 560-8531, Japan [2] CREST, Japan Science Technology Agency, Saitama 332-0012, Japan
| | - Yoichi Shiota
- 1] Graduate School of Engineering Science, Osaka University, Osaka 560-8531, Japan [2] CREST, Japan Science Technology Agency, Saitama 332-0012, Japan
| | - Shinji Miwa
- 1] Graduate School of Engineering Science, Osaka University, Osaka 560-8531, Japan [2] CREST, Japan Science Technology Agency, Saitama 332-0012, Japan
| | - Yoshishige Suzuki
- 1] Graduate School of Engineering Science, Osaka University, Osaka 560-8531, Japan [2] CREST, Japan Science Technology Agency, Saitama 332-0012, Japan
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Qiu X, Deorani P, Narayanapillai K, Lee KS, Lee KJ, Lee HW, Yang H. Angular and temperature dependence of current induced spin-orbit effective fields in Ta/CoFeB/MgO nanowires. Sci Rep 2014; 4:4491. [PMID: 24670317 PMCID: PMC3967151 DOI: 10.1038/srep04491] [Citation(s) in RCA: 182] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Accepted: 03/12/2014] [Indexed: 11/16/2022] Open
Abstract
Current induced spin-orbit effective magnetic fields in metal/ferromagnet/oxide trilayers provide a new way to manipulate the magnetization, which is an alternative to the conventional current induced spin transfer torque arising from noncollinear magnetization. Ta/CoFeB/MgO structures are expected to be useful for non-volatile memories and logic devices due to its perpendicular anisotropy and large current induced spin-orbit effective fields. However many aspects such as the angular and temperature dependent phenomena of the effective fields are little understood. Here, we evaluate the angular and temperature dependence of the current-induced spin-orbit effective fields considering contributions from both the anomalous and planar Hall effects. The longitudinal and transverse components of effective fields are found to have strong angular dependence on the magnetization direction at 300 K. The transverse field decreases significantly with decreasing temperature, whereas the longitudinal field shows weaker temperature dependence. Our results reveal important features and provide an opportunity for a more comprehensive understanding of current induced spin-orbit effective fields.
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Affiliation(s)
- Xuepeng Qiu
- Department of Electrical and Computer Engineering, National University of Singapore, 117576, Singapore
| | - Praveen Deorani
- Department of Electrical and Computer Engineering, National University of Singapore, 117576, Singapore
| | | | - Ki-Seung Lee
- Department of Materials Science and Engineering, Korea University, Seoul 136-701, Korea
- Spin Convergence Research Center, Korea Institute of Science and Technology, Seoul 136-791, Korea
| | - Kyung-Jin Lee
- Department of Materials Science and Engineering, Korea University, Seoul 136-701, Korea
- Spin Convergence Research Center, Korea Institute of Science and Technology, Seoul 136-791, Korea
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 136-713, Korea
| | - Hyun-Woo Lee
- PCTP and Department of Physics, Pohang University of Science and Technology, Kyungbuk 790-784, Korea
| | - Hyunsoo Yang
- Department of Electrical and Computer Engineering, National University of Singapore, 117576, Singapore
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