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Yang X, Qiu L, Li Y, Xue HP, Liu JN, Sun R, Yang QL, Gai XS, Wei YS, Comstock AH, Sun D, Zhang XQ, He W, Hou Y, Cheng ZH. Anisotropic Nonlocal Damping in Ferromagnet/α-GeTe Bilayers Enabled by Splitting Energy Bands. PHYSICAL REVIEW LETTERS 2023; 131:186703. [PMID: 37977650 DOI: 10.1103/physrevlett.131.186703] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Revised: 07/20/2023] [Accepted: 10/06/2023] [Indexed: 11/19/2023]
Abstract
The understanding and manipulation of anisotropic Gilbert damping is crucial for both fundamental research and versatile engineering and optimization. Although several works on anisotropic damping have been reported, no direct relationship between the band structure and anisotropic damping was established. Here, we observed an anisotropic damping in Fe/GeTe manipulated by the symmetric band structures of GeTe via angle-resolved photoemission spectroscopy. Moreover, the anisotropic damping can be modified by the symmetry of band structures. Our Letter provides insightful understandings of the anisotropic Gilbert damping in ferromagnets interfaced with Rashba semiconductors and suggests the possibility of manipulating the Gilbert damping by band engineering.
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Affiliation(s)
- Xu Yang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
| | - Liang Qiu
- Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices, Center for Neutron Science and Technology, School of Physics, Sun Yat-Sen University, Guangzhou 510275, China
| | - Yan Li
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Hao-Pu Xue
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jia-Nan Liu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Rui Sun
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Qing-Lin Yang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Xue-Song Gai
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yan-Sheng Wei
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Andrew H Comstock
- Department of Physics and Organic and Carbon Electronics Laboratory (ORCEL), North Carolina State University, Raleigh, North Carolina 27695, USA
| | - Dali Sun
- Department of Physics and Organic and Carbon Electronics Laboratory (ORCEL), North Carolina State University, Raleigh, North Carolina 27695, USA
| | - Xiang-Qun Zhang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Wei He
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
| | - Yusheng Hou
- Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices, Center for Neutron Science and Technology, School of Physics, Sun Yat-Sen University, Guangzhou 510275, China
| | - Zhao-Hua Cheng
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China
- School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
- Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China
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2
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Spin-orbit torques in normal metal/Nb/ferromagnet heterostructures. Sci Rep 2021; 11:21081. [PMID: 34702943 PMCID: PMC8548299 DOI: 10.1038/s41598-021-99745-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2021] [Accepted: 09/27/2021] [Indexed: 11/08/2022] Open
Abstract
Quantifying the spin–orbit torque (SOT) efficiency with changing the layer thickness is crucial for understanding the physical background of SOT. This study investigates the Nb-thickness-dependent SOT efficiency of two types of layered heterostructures: Ta/Nb/CoFeB and Pt/Nb/CoFeB. We find that the Nb thickness dependence of the SOT efficiency in the two samples is quite different. In the Pt/Nb series, the SOT sign changes according to the thickness variation because Pt and Nb have different spin–orbit coupling signs. We observe the resulting reversal in switching polarity through current-induced SOT switching experiments. However, due to the same spin–orbit coupling signs of Ta and Nb, no such polarity reversal was observed in Ta/Nb series. Further, we extract the spin diffusion length of Nb in each heterostructure. These results provide a systematic understanding of the material- and thickness-dependent SOT characteristics.
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3
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Magnon Torque Transferred into a Magnetic Insulator through an Antiferromagnetic Insulator. NANOMATERIALS 2021; 11:nano11112766. [PMID: 34835536 PMCID: PMC8625957 DOI: 10.3390/nano11112766] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 10/12/2021] [Accepted: 10/15/2021] [Indexed: 12/04/2022]
Abstract
Electrical spin-orbit torque (SOT) in magnetic insulators (MI) has been intensively studied due to its advantages in spin-orbitronic devices with ultralow energy consumption. However, the magnon torque in the MIs, which has the potential to further lower the energy consumption, still remains elusive. In this work, we demonstrate the efficient magnon torque transferred into an MI through an antiferromagnetic insulator. By fabricating a Pt/NiO/Tm3Fe5O12 heterostructure with different NiO thicknesses, we have systematically investigated the evolution of the transferred magnon torque. We show that the magnon torque efficiency transferred through the NiO into the MI can retain a high value (∼50%), which is comparable to the previous report for the magnon torque transferred into the metallic magnet. Our study manifests the feasibility of realizing the pure magnon-based spin-orbitronic devices with ultralow energy consumption and high efficiency.
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Lyalin I, Cheng S, Kawakami RK. Spin-Orbit Torque in Bilayers of Kagome Ferromagnet Fe 3Sn 2 and Pt. NANO LETTERS 2021; 21:6975-6982. [PMID: 34380320 DOI: 10.1021/acs.nanolett.1c02270] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Spin-orbit torque phenomena enable efficient manipulation of the magnetization in ferromagnet/heavy metal bilayer systems for prospective magnetic memory and logic applications. Kagome magnets are of particular interest for spin-orbit torque due to the interplay of magnetic order and the nontrivial band topology (e.g., flat bands and Dirac and Weyl points). Here we demonstrate spin-orbit torque and quantify its efficiency in a bilayer system of topological kagome ferromagnet Fe3Sn2 and platinum. We use two different techniques, one based on the quasistatic magneto-optic Kerr effect (MOKE) and another based on time-resolved MOKE, to quantify spin-orbit torque. Both techniques give a consistent value of the effective spin Hall angle of the Fe3Sn2/Pt system. Our work may lead to further advances in spintronics based on topological kagome magnets.
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Affiliation(s)
- Igor Lyalin
- Department of Physics, The Ohio State University, Columbus, Ohio 43210, United States
| | - Shuyu Cheng
- Department of Physics, The Ohio State University, Columbus, Ohio 43210, United States
| | - Roland K Kawakami
- Department of Physics, The Ohio State University, Columbus, Ohio 43210, United States
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5
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Huang X, Sayed S, Mittelstaedt J, Susarla S, Karimeddiny S, Caretta L, Zhang H, Stoica VA, Gosavi T, Mahfouzi F, Sun Q, Ercius P, Kioussis N, Salahuddin S, Ralph DC, Ramesh R. Novel Spin-Orbit Torque Generation at Room Temperature in an All-Oxide Epitaxial La 0.7 Sr 0.3 MnO 3 /SrIrO 3 System. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2021; 33:e2008269. [PMID: 33960025 DOI: 10.1002/adma.202008269] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/07/2020] [Revised: 02/27/2021] [Indexed: 06/12/2023]
Abstract
Spin-orbit torques (SOTs) that arise from materials with large spin-orbit coupling offer a new pathway for energy-efficient and fast magnetic information storage. SOTs in conventional heavy metals and topological insulators are explored extensively, while 5d transition metal oxides, which also host ions with strong spin-orbit coupling, are a relatively new territory in the field of spintronics. An all-oxide, SrTiO3 (STO)//La0.7 Sr0.3 MnO3 (LSMO)/SrIrO3 (SIO) heterostructure with lattice-matched crystal structure is synthesized, exhibiting an epitaxial and atomically sharp interface between the ferromagnetic LSMO and the high spin-orbit-coupled metal SIO. Spin-torque ferromagnetic resonance (ST-FMR) is used to probe the effective magnetization and the SOT efficiency in LSMO/SIO heterostructures grown on STO substrates. Remarkably, epitaxial LSMO/SIO exhibits a large SOT efficiency, ξ|| = 1, while retaining a reasonably low shunting factor and increasing the effective magnetization of LSMO by ≈50%. The findings highlight the significance of epitaxy as a powerful tool to achieve a high SOT efficiency, explore the rich physics at the epitaxial interface, and open up a new pathway for designing next-generation energy-efficient spintronic devices.
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Affiliation(s)
- Xiaoxi Huang
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
| | - Shehrin Sayed
- Department of Electrical Engineering and Computer Science, University of California, Berkeley, CA, 94720, USA
| | | | - Sandhya Susarla
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Saba Karimeddiny
- Department of Physics, Cornell University, Ithaca, NY, 14853, USA
| | - Lucas Caretta
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
| | - Hongrui Zhang
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
| | - Vladimir A Stoica
- Department of Materials Science and Engineering, Pennsylvania State University, University Park, PA, 16802, USA
| | - Tanay Gosavi
- Components Research, Intel Corporation, Hillsboro, OR, 97124, USA
| | - Farzad Mahfouzi
- Department of Physics, California State University Northridge, Northridge, CA, 91330, USA
| | - Qilong Sun
- Department of Physics, California State University Northridge, Northridge, CA, 91330, USA
| | - Peter Ercius
- National Center for Electron Microscopy, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
| | - Nicholas Kioussis
- Department of Physics, California State University Northridge, Northridge, CA, 91330, USA
| | - Sayeef Salahuddin
- Department of Electrical Engineering and Computer Science, University of California, Berkeley, CA, 94720, USA
| | - Daniel C Ralph
- Department of Physics, Cornell University, Ithaca, NY, 14853, USA
- Kavli Institute at Cornell for Nanoscale Science, Ithaca, NY, 14853, USA
| | - Ramamoorthy Ramesh
- Department of Materials Science and Engineering, University of California, Berkeley, CA, 94720, USA
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA
- Department of Physics, University of California, Berkeley, CA, 94720, USA
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6
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ANDO K. Generation and manipulation of current-induced spin-orbit torques. PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2021; 97:499-519. [PMID: 34759072 PMCID: PMC8610784 DOI: 10.2183/pjab.97.025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Accepted: 08/12/2021] [Indexed: 06/13/2023]
Abstract
An emerging field of spintronics, spin-orbitronics, aims to discover novel phenomena and functionalities originating from spin-orbit coupling in solid-state devices. The development of spin-orbitronics promises a fundamental understanding of spin physics in condensed matter, as well as smaller, faster, and far-more energy-efficient spin-based devices. Of particular importance in this field is current-induced spin-orbit torques, which trigger magnetic dynamics by the transfer of angular momentum from an atomic lattice to local magnetization through the spin-orbit coupling. The spin-orbit torque has attracted extensive attention for its fascinating relativistic and quantum mechanical nature, as well as prospective nanoelectronic applications. In this article, we review our studies on the generation and manipulation of current-induced spin-orbit torques.
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Affiliation(s)
- Kazuya ANDO
- Department of Applied Physics and Physico-Informatics, Keio University, Yokohama, Kanagawa, Japan
- Keio Institute of Pure and Applied Science, Keio University, Yokohama, Kanagawa, Japan
- Center for Spintronics Research Network, Keio University, Yokohama, Kanagawa, Japan
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7
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Amin VP, Haney PM, Stiles MD. Interfacial spin-orbit torques. JOURNAL OF APPLIED PHYSICS 2020; 128:10.1063/5.0024019. [PMID: 34121763 PMCID: PMC8194107 DOI: 10.1063/5.0024019] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/04/2020] [Accepted: 09/30/2020] [Indexed: 06/12/2023]
Abstract
Spin-orbit torques offer a promising mechanism for electrically controlling magnetization dynamics in nanoscale heterostructures. While spin-orbit torques occur predominately at interfaces, the physical mechanisms underlying these torques can originate in both the bulk layers and at interfaces. Classifying spin-orbit torques based on the region that they originate in provides clues as to how to optimize the effect. While most bulk spin-orbit torque contributions are well studied, many of the interfacial contributions allowed by symmetry have yet to be fully explored theoretically and experimentally. To facilitate progress, we review interfacial spin-orbit torques from a semiclassical viewpoint and relate these contributions to recent experimental results. Within the same model, we show the relationship between different interface transport parameters. For charges and spins flowing perpendicular to the interface, interfacial spin-orbit coupling both modifies the mixing conductance of magnetoelectronic circuit theory and gives rise to spin memory loss. For in-plane electric fields, interfacial spin-orbit coupling gives rise to torques described by spin-orbit filtering, spin swapping and precession. In addition, these same interfacial processes generate spin currents that flow into the non-magnetic layer. For in-plane electric fields in trilayer structures, the spin currents generated at the interface between one ferromagnetic layer and the non-magnetic spacer layer can propagate through the non-magnetic layer to produce novel torques on the other ferromagnetic layer.
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Affiliation(s)
- V. P. Amin
- Department of Chemistry & Biochemistry, University of Maryland, College Park, MD 20742, USA
- National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - P. M. Haney
- National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
| | - M. D. Stiles
- National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
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8
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Husain S, Chen X, Gupta R, Behera N, Kumar P, Edvinsson T, García-Sánchez F, Brucas R, Chaudhary S, Sanyal B, Svedlindh P, Kumar A. Large Damping-Like Spin-Orbit Torque in a 2D Conductive 1T-TaS 2 Monolayer. NANO LETTERS 2020; 20:6372-6380. [PMID: 32786947 PMCID: PMC7496736 DOI: 10.1021/acs.nanolett.0c01955] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Revised: 08/04/2020] [Indexed: 06/11/2023]
Abstract
A damping-like spin-orbit torque (SOT) is a prerequisite for ultralow-power spin logic devices. Here, we report on the damping-like SOT in just one monolayer of the conducting transition-metal dichalcogenide (TMD) TaS2 interfaced with a NiFe (Py) ferromagnetic layer. The charge-spin conversion efficiency is found to be 0.25 ± 0.03 in TaS2(0.88)/Py(7), and the spin Hall conductivity (14.9×105ℏ2eΩ-1m-1) is found to be superior to values reported for other TMDs. We also observed sizable field-like torque in this heterostructure. The origin of this large damping-like SOT can be found in the interfacial properties of the TaS2/Py heterostructure, and the experimental findings are complemented by the results from density functional theory calculations. It is envisioned that the interplay between interfacial spin-orbit coupling and crystal symmetry yielding large damping-like SOT. The dominance of damping-like torque demonstrated in our study provides a promising path for designing the next-generation conducting TMD-based low-powered quantum memory devices.
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Affiliation(s)
- Sajid Husain
- Department
of Materials Science, Uppsala University, Box 35, SE-751 03 Uppsala, Sweden
| | - Xin Chen
- Department
of Physics and Astronomy, Materials Theory, Uppsala University, Box 516, SE-751 20 Uppsala, Sweden
| | - Rahul Gupta
- Department
of Materials Science, Uppsala University, Box 35, SE-751 03 Uppsala, Sweden
| | - Nilamani Behera
- Department
of Materials Science, Uppsala University, Box 35, SE-751 03 Uppsala, Sweden
| | - Prabhat Kumar
- Department
of Thin Films and Nanostructures, Institute
of Physics of the Czech Academy of Sciences, Cukrovarnická 10/112, 162 00 Prague, Czech Republic
| | - Tomas Edvinsson
- Department
of Materials Science, Uppsala University, Box 35, SE-751 03 Uppsala, Sweden
| | - F. García-Sánchez
- Departamento
de Física Aplicada, University of
Salamanca, Pza de la Merced s/n, 37008 Salamanca, Spain
| | - Rimantas Brucas
- Department
of Materials Science, Uppsala University, Box 35, SE-751 03 Uppsala, Sweden
| | - Sujeet Chaudhary
- Thin
Film Laboratory, Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016, India
| | - Biplab Sanyal
- Department
of Physics and Astronomy, Materials Theory, Uppsala University, Box 516, SE-751 20 Uppsala, Sweden
| | - Peter Svedlindh
- Department
of Materials Science, Uppsala University, Box 35, SE-751 03 Uppsala, Sweden
| | - Ankit Kumar
- Department
of Materials Science, Uppsala University, Box 35, SE-751 03 Uppsala, Sweden
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Ryu J, Lee S, Lee KJ, Park BG. Current-Induced Spin-Orbit Torques for Spintronic Applications. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e1907148. [PMID: 32141681 DOI: 10.1002/adma.201907148] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 12/13/2019] [Indexed: 06/10/2023]
Abstract
Control of magnetization in magnetic nanostructures is essential for development of spintronic devices because it governs fundamental device characteristics such as energy consumption, areal density, and operation speed. In this respect, spin-orbit torque (SOT), which originates from the spin-orbit interaction, has been widely investigated due to its efficient manipulation of the magnetization using in-plane current. SOT spearheads novel spintronic applications including high-speed magnetic memories, reconfigurable logics, and neuromorphic computing. Herein, recent advances in SOT research, highlighting the considerable benefits and challenges of SOT-based spintronic devices, are reviewed. First, the materials and structural engineering that enhances SOT efficiency are discussed. Then major experimental results for field-free SOT switching of perpendicular magnetization are summarized, which includes the introduction of an internal effective magnetic field and the generation of a distinct spin current with out-of-plane spin polarization. Finally, advanced SOT functionalities are presented, focusing on the demonstration of reconfigurable and complementary operation in spin logic devices.
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Affiliation(s)
- Jeongchun Ryu
- Department of Materials Science and Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea
| | - Soogil Lee
- Department of Materials Science and Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea
| | - Kyung-Jin Lee
- Department of Materials Science and Engineering and KU-KIST Graduate School of Converging Science and Technology, Korea University, 145 Anam-ro, Anam-dong, Seongbuk-gu, Seoul, 02841, Republic of Korea
| | - Byong-Guk Park
- Department of Materials Science and Engineering, KAIST, 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea
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10
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Kageyama Y, Tazaki Y, An H, Harumoto T, Gao T, Shi J, Ando K. Spin-orbit torque manipulated by fine-tuning of oxygen-induced orbital hybridization. SCIENCE ADVANCES 2019; 5:eaax4278. [PMID: 31701004 PMCID: PMC6824862 DOI: 10.1126/sciadv.aax4278] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/22/2019] [Accepted: 09/17/2019] [Indexed: 06/10/2023]
Abstract
Current-induced spin-orbit torques provide an effective way to manipulate magnetization in spintronic devices, promising for fast switching applications in nonvolatile memory and logic units. Recent studies have revealed that the spin-orbit torque is strongly altered by the oxidation of heterostructures with broken inversion symmetry. Although this finding opens a new field of metal-oxide spin-orbitronics, the role of the oxidation in the spin-orbit physics is still unclear. Here, we demonstrate a marked enhancement of the spin-orbit torque induced by a fine-tuning of oxygen-induced modification of orbital hybridization. This is evidenced by a concomitant enhancement of the interface spin-orbit torque, interface spin loss, and interface perpendicular magnetic anisotropy within a narrow range of the oxidation level of metallic heterostructures. This result reveals the crucial role of the atomic-scale effects in the generation of the spin-orbit torques, opening the door to atomic-level engineering of the spin-orbit physics.
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Affiliation(s)
- Yuito Kageyama
- Department of Applied Physics and Physico-Informatics, Keio University, Yokohama 223-8522, Japan
| | - Yuya Tazaki
- Department of Applied Physics and Physico-Informatics, Keio University, Yokohama 223-8522, Japan
| | - Hongyu An
- Department of Applied Physics and Physico-Informatics, Keio University, Yokohama 223-8522, Japan
| | - Takashi Harumoto
- School of Materials and Chemical Technology, Tokyo Institute of Technology, Tokyo 152-8552, Japan
| | - Tenghua Gao
- Department of Applied Physics and Physico-Informatics, Keio University, Yokohama 223-8522, Japan
| | - Ji Shi
- School of Materials and Chemical Technology, Tokyo Institute of Technology, Tokyo 152-8552, Japan
| | - Kazuya Ando
- Department of Applied Physics and Physico-Informatics, Keio University, Yokohama 223-8522, Japan
- Center for Spintronics Research Network (CSRN), Keio University, Yokohama 223-8522, Japan
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11
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Anisotropic spin-orbit torque generation in epitaxial SrIrO 3 by symmetry design. Proc Natl Acad Sci U S A 2019; 116:16186-16191. [PMID: 31350347 DOI: 10.1073/pnas.1812822116] [Citation(s) in RCA: 22] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Spin-orbit coupling (SOC), the interaction between the electron spin and the orbital angular momentum, can unlock rich phenomena at interfaces, in particular interconverting spin and charge currents. Conventional heavy metals have been extensively explored due to their strong SOC of conduction electrons. However, spin-orbit effects in classes of materials such as epitaxial 5d-electron transition-metal complex oxides, which also host strong SOC, remain largely unreported. In addition to strong SOC, these complex oxides can also provide the additional tuning knob of epitaxy to control the electronic structure and the engineering of spin-to-charge conversion by crystalline symmetry. Here, we demonstrate room-temperature generation of spin-orbit torque on a ferromagnet with extremely high efficiency via the spin-Hall effect in epitaxial metastable perovskite SrIrO3 We first predict a large intrinsic spin-Hall conductivity in orthorhombic bulk SrIrO3 arising from the Berry curvature in the electronic band structure. By manipulating the intricate interplay between SOC and crystalline symmetry, we control the spin-Hall torque ratio by engineering the tilt of the corner-sharing oxygen octahedra in perovskite SrIrO3 through epitaxial strain. This allows the presence of an anisotropic spin-Hall effect due to a characteristic structural anisotropy in SrIrO3 with orthorhombic symmetry. Our experimental findings demonstrate the heteroepitaxial symmetry design approach to engineer spin-orbit effects. We therefore anticipate that these epitaxial 5d transition-metal oxide thin films can be an ideal building block for low-power spintronics.
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12
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Xie Q, Lin W, Yang B, Shu X, Chen S, Liu L, Yu X, Breese MBH, Zhou T, Yang M, Zhang Z, Wang S, Yang H, Chai J, Han X, Chen J. Giant Enhancements of Perpendicular Magnetic Anisotropy and Spin-Orbit Torque by a MoS 2 Layer. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2019; 31:e1900776. [PMID: 30957913 DOI: 10.1002/adma.201900776] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Revised: 03/22/2019] [Indexed: 06/09/2023]
Abstract
2D transition metal dichalcogenides have attracted much attention in the field of spintronics due to their rich spin-dependent properties. The promise of highly compact and low-energy-consumption spin-orbit torque (SOT) devices motivates the search for structures and materials that can satisfy the requirements of giant perpendicular magnetic anisotropy (PMA) and large SOT simultaneously in SOT-based magnetic memory. Here, it is demonstrated that PMA and SOT in a heavy metal/transition metal ferromagnet structure, Pt/[Co/Ni]2 , can be greatly enhanced by introducing a molybdenum disulfide (MoS2 ) underlayer. According to first-principles calculation and X-ray absorption spectroscopy (XAS), the enhancement of the PMA is ascribed to the modification of the orbital hybridization at the interface of Pt/Co due to MoS2 . The enhancement of SOT by the role played by MoS2 is explained, which is strongly supported by the identical behavior of SOT and PMA as a function of Pt thickness. This work provides new possibilities to integrate 2D materials into promising spintronics devices.
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Affiliation(s)
- Qidong Xie
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
- Department of Electronic Material, Institute of Material Research and Engineering, A*STAR, Singapore, 138634, Singapore
| | - Weinan Lin
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Baishun Yang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, 100190, China
- CAS Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201, China
| | - Xinyu Shu
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Shaohai Chen
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Liang Liu
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Xiaojiang Yu
- Singapore Synchrotron Light Source, National University of Singapore, Singapore, 117575, Singapore
| | - Mark B H Breese
- Singapore Synchrotron Light Source, National University of Singapore, Singapore, 117575, Singapore
| | - Tiejun Zhou
- College of electronics and information, Hangzhou Dianzi University, Hangzhou, 310018, China
| | - Ming Yang
- Department of Electronic Material, Institute of Material Research and Engineering, A*STAR, Singapore, 138634, Singapore
| | - Zheng Zhang
- Department of Electronic Material, Institute of Material Research and Engineering, A*STAR, Singapore, 138634, Singapore
| | - Shijie Wang
- Department of Electronic Material, Institute of Material Research and Engineering, A*STAR, Singapore, 138634, Singapore
| | - Hongxin Yang
- CAS Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, Ningbo, 315201, China
| | - Jianwei Chai
- Department of Electronic Material, Institute of Material Research and Engineering, A*STAR, Singapore, 138634, Singapore
| | - Xiufeng Han
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing, 100190, China
| | - Jingsheng Chen
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
- Suzhou Research Institute, National University of Singapore, Suzhou, 215123, China
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13
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Das S, Avraham L, Telepinsky Y, Mor V, Schultz M, Klein L. Magnetization switching of multi-state magnetic structures with current-induced torques. Sci Rep 2018; 8:15160. [PMID: 30310132 PMCID: PMC6181950 DOI: 10.1038/s41598-018-33554-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Accepted: 10/02/2018] [Indexed: 11/12/2022] Open
Abstract
Spintronic devices often require the ability to locally change the magnetic configuration of ferromagnetic structures on a sub-micron scale. A promising route for achieving this goal is the use of heavy metal/ferromagnetic heterostructures where current flowing through the heavy metal layer generates field-like and anti-damping like torques on the magnetic layer. Commonly, such torques are used to switch magnets with a uniaxial anisotropy between two uniformly magnetized states. Here, we use such torques to switch magnetization in Ta/Ni0.80Fe0.20 heterostructures with uniaxial and biaxial anisotropy, where in the latter the magnetization is non-uniform. The anisotropies are induced by shape and the magnetic state is monitored using the planar Hall effect. As structures with several easy axes induced by shape can be part of a magnetic memory element, the results pave the way for multi-level magnetic memory with spin-orbit torque switching.
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Affiliation(s)
- Shubhankar Das
- Department of Physics, Nano-magnetism Research Center, Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan, 52900, Israel
| | - Liran Avraham
- Department of Physics, Nano-magnetism Research Center, Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan, 52900, Israel
| | - Yevgeniy Telepinsky
- Department of Physics, Nano-magnetism Research Center, Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan, 52900, Israel
| | - Vladislav Mor
- Department of Physics, Nano-magnetism Research Center, Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan, 52900, Israel
| | - Moty Schultz
- Department of Physics, Nano-magnetism Research Center, Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan, 52900, Israel
| | - Lior Klein
- Department of Physics, Nano-magnetism Research Center, Institute of Nanotechnology and Advanced Materials, Bar-Ilan University, Ramat-Gan, 52900, Israel.
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14
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Yang Y, Luo Z, Wu H, Xu Y, Li RW, Pennycook SJ, Zhang S, Wu Y. Anomalous Hall magnetoresistance in a ferromagnet. Nat Commun 2018; 9:2255. [PMID: 29884868 PMCID: PMC5993777 DOI: 10.1038/s41467-018-04712-9] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2017] [Accepted: 05/17/2018] [Indexed: 11/09/2022] Open
Abstract
The anomalous Hall effect, observed in conducting ferromagnets with broken time-reversal symmetry, offers the possibility to couple spin and orbital degrees of freedom of electrons in ferromagnets. In addition to charge, the anomalous Hall effect also leads to spin accumulation at the surfaces perpendicular to both the current and magnetization direction. Here, we experimentally demonstrate that the spin accumulation, subsequent spin backflow, and spin-charge conversion can give rise to a different type of spin current-related spin current related magnetoresistance, dubbed here as the anomalous Hall magnetoresistance, which has the same angular dependence as the recently discovered spin Hall magnetoresistance. The anomalous Hall magnetoresistance is observed in four types of samples: co-sputtered (Fe1-xMn x )0.6Pt0.4, Fe1-xMn x /Pt multilayer, Fe1-xMn x with x = 0.17-0.65 and Fe, and analyzed using the drift-diffusion model. Our results provide an alternative route to study charge-spin conversion in ferromagnets and to exploit it for potential spintronic applications.
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Affiliation(s)
- Yumeng Yang
- Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore, 117583, Singapore
| | - Ziyan Luo
- Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore, 117583, Singapore
| | - Haijun Wu
- Department of Materials Science & Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Yanjun Xu
- Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore, 117583, Singapore
| | - Run-Wei Li
- Key Laboratory of Magnetic Materials and Devices, Ningbo Institute of Materials Technology and Engineering, Chinese Academy of Sciences, 315201, Ningbo, Republic of China
| | - Stephen J Pennycook
- Department of Materials Science & Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Shufeng Zhang
- Department of Physics, University of Arizona, Tucson, AZ, 85721, USA
| | - Yihong Wu
- Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, Singapore, 117583, Singapore.
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15
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Qiu X, Shi Z, Fan W, Zhou S, Yang H. Characterization and Manipulation of Spin Orbit Torque in Magnetic Heterostructures. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2018; 30:e1705699. [PMID: 29468735 DOI: 10.1002/adma.201705699] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2017] [Revised: 11/01/2017] [Indexed: 06/08/2023]
Abstract
Electrical-current-induced magnetization switching is a keystone concept in the development of spintronics devices. In the last few years, this field has experienced a significant boost with the discovery of spin orbit torque (SOT) in magnetic heterostructures. Here, the recent results as to the characterization and manipulation of SOT in various heavy-metal/ferromagnet heterostructures are summarized. First, different electrical measurement methods that allow the physical features of SOT to be revealed are introduced. Second, it is shown that SOT in magnetic heterostructures can be manipulated via various material engineering approaches. The interfacial and bulk contributions of SOT are also discussed. These results advance the understanding of SOT and provide novel approaches toward energy-efficient spintronic devices.
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Affiliation(s)
- Xuepeng Qiu
- Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology and School of Physics Science and Engineering, Tongji University, Shanghai, 200092, China
| | - Zhong Shi
- Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology and School of Physics Science and Engineering, Tongji University, Shanghai, 200092, China
| | - Weijia Fan
- Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology and School of Physics Science and Engineering, Tongji University, Shanghai, 200092, China
| | - Shiming Zhou
- Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology and School of Physics Science and Engineering, Tongji University, Shanghai, 200092, China
| | - Hyunsoo Yang
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, 117576, Singapore
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16
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An H, Ohno T, Kanno Y, Kageyama Y, Monnai Y, Maki H, Shi J, Ando K. Current-induced magnetization switching using an electrically insulating spin-torque generator. SCIENCE ADVANCES 2018; 4:eaar2250. [PMID: 29507887 PMCID: PMC5834006 DOI: 10.1126/sciadv.aar2250] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/16/2017] [Accepted: 01/19/2018] [Indexed: 05/28/2023]
Abstract
Current-induced magnetization switching through spin-orbit torques is the fundamental building block of spin-orbitronics, which promises high-performance, low-power memory and logic devices. The spin-orbit torques generally arise from spin-orbit coupling of heavy metals. However, even in a heterostructure where a metallic magnet is sandwiched by two different insulators, a nonzero spin-orbit torque is expected because of the broken inversion symmetry; an electrical insulator can be a source of the spin-orbit torques. We demonstrate current-induced magnetization switching using an insulator. We show that oxygen incorporation into the most widely used spintronic material, Pt, turns the heavy metal into an electrically insulating generator of the spin-orbit torques, which enables the electrical switching of perpendicular magnetization in a ferrimagnet sandwiched by insulating oxides. We also show that the spin-orbit torques generated from the Pt oxide can be controlled electrically through voltage-driven oxygen migration. These findings open a route toward energy-efficient, voltage-programmable spin-orbit devices based on insulating metal oxides.
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Affiliation(s)
- Hongyu An
- Department of Applied Physics and Physico-Informatics, Keio University, Yokohama 223-8522, Japan
| | - Takeo Ohno
- World Premier International Research Center Initiative, Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
- PRESTO (Precursory Research for Embryonic Science and Technology), Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan
| | - Yusuke Kanno
- Department of Applied Physics and Physico-Informatics, Keio University, Yokohama 223-8522, Japan
| | - Yuito Kageyama
- Department of Applied Physics and Physico-Informatics, Keio University, Yokohama 223-8522, Japan
| | - Yasuaki Monnai
- Department of Applied Physics and Physico-Informatics, Keio University, Yokohama 223-8522, Japan
| | - Hideyuki Maki
- Department of Applied Physics and Physico-Informatics, Keio University, Yokohama 223-8522, Japan
- PRESTO (Precursory Research for Embryonic Science and Technology), Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan
| | - Ji Shi
- School of Materials and Chemical Technology, Tokyo Institute of Technology, Tokyo 152-8552, Japan
| | - Kazuya Ando
- Department of Applied Physics and Physico-Informatics, Keio University, Yokohama 223-8522, Japan
- PRESTO (Precursory Research for Embryonic Science and Technology), Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan
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17
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Hals KMD, Everschor-Sitte K. New Boundary-Driven Twist States in Systems with Broken Spatial Inversion Symmetry. PHYSICAL REVIEW LETTERS 2017; 119:127203. [PMID: 29341659 DOI: 10.1103/physrevlett.119.127203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Indexed: 06/07/2023]
Abstract
A full description of a magnetic sample includes a correct treatment of the boundary conditions (BCs). This is in particular important in thin film systems, where even bulk properties might be modified by the properties of the boundary of the sample. We study generic ferromagnets with broken spatial inversion symmetry and derive the general micromagnetic BCs of a system with Dzyaloshinskii-Moriya interaction (DMI). We demonstrate that the BCs require the full tensorial structure of the third-rank DMI tensor and not just the antisymmetric part, which is usually taken into account. Specifically, we study systems with C_{∞v} symmetry and explore the consequences of the DMI. Interestingly, we find that the DMI already in the simplest case of a ferromagnetic thin film leads to a purely boundary-driven magnetic twist state at the edges of the sample. The twist state represents a new type of DMI-induced spin structure, which is completely independent of the internal DMI field. We estimate the size of the texture-induced magnetoresistance effect being in the range of that of domain walls.
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Affiliation(s)
- Kjetil M D Hals
- Institute of Physics, Johannes Gutenberg University Mainz, 55128 Mainz, Germany
- Faculty of Engineering and Science, Western Norway University of Applied Sciences, No-6803 Førde, Norway
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18
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Wang T, Wang W, Xie Y, Warsi MA, Wu J, Chen Y, Lorenz VO, Fan X, Xiao JQ. Large spin Hall angle in vanadium film. Sci Rep 2017; 7:1306. [PMID: 28465585 PMCID: PMC5430949 DOI: 10.1038/s41598-017-01112-9] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2016] [Accepted: 03/22/2017] [Indexed: 11/13/2022] Open
Abstract
We report a large spin Hall angle observed in vanadium films sputter-grown at room temperature, which have small grain size and consist of a mixture of body centered tetragonal (bct) and body centered cubic (bcc) structures. The spin Hall angle is as large as θV = −0.071 ± 0.003, comparable to that of platinum, θPt = 0.076 ± 0.007, and is much larger than that of bcc V film grown at 400 °C, θV_bcc = −0.012 ± 0.002. Similar to β-tantalum and β-tungsten, the sputter-grown V films also have a high resistivity of more than 200 μΩ∙cm. Surprisingly, the spin diffusion length is still long at 16.3 nm. This finding not only indicates that specific crystalline structure can lead to a large spin Hall effect but also suggests 3d light metals should not be ruled out in the search for materials with large spin Hall angle.
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Affiliation(s)
- T Wang
- Department of Physics and Astronomy, University of Delaware, Newark, Delaware, 19716, USA
| | - W Wang
- Department of Physics and Astronomy, University of Delaware, Newark, Delaware, 19716, USA.,Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA
| | - Y Xie
- Department of Physics and Astronomy, University of Delaware, Newark, Delaware, 19716, USA
| | - M A Warsi
- Department of Physics and Astronomy, University of Delaware, Newark, Delaware, 19716, USA
| | - J Wu
- Department of Physics and Astronomy, University of Delaware, Newark, Delaware, 19716, USA
| | - Y Chen
- Department of Physics and Astronomy, University of Delaware, Newark, Delaware, 19716, USA
| | - V O Lorenz
- Department of Physics and Astronomy, University of Delaware, Newark, Delaware, 19716, USA.,Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois, 61801, USA
| | - X Fan
- Department of Physics and Astronomy, University of Delaware, Newark, Delaware, 19716, USA.,Department of Physics and Astronomy, University of Denver, Denver, Colorado, 80208, USA
| | - J Q Xiao
- Department of Physics and Astronomy, University of Delaware, Newark, Delaware, 19716, USA.
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19
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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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20
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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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21
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Shao Q, Yu G, Lan YW, Shi Y, Li MY, Zheng C, Zhu X, Li LJ, Amiri PK, Wang KL. Strong Rashba-Edelstein Effect-Induced Spin-Orbit Torques in Monolayer Transition Metal Dichalcogenide/Ferromagnet Bilayers. NANO LETTERS 2016; 16:7514-7520. [PMID: 27960524 DOI: 10.1021/acs.nanolett.6b03300] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
The electronic and optoelectronic properties of two-dimensional materials have been extensively explored in graphene and layered transition metal dichalcogenides (TMDs). Spintronics in these two-dimensional materials could provide novel opportunities for future electronics, for example, efficient generation of spin current, which should enable the efficient manipulation of magnetic elements. So far, the quantitative determination of charge current-induced spin current and spin-orbit torques (SOTs) on the magnetic layer adjacent to two-dimensional materials is still lacking. Here, we report a large SOT generated by current-induced spin accumulation through the Rashba-Edelstein effect in the composites of monolayer TMD (MoS2 or WSe2)/CoFeB bilayer. The effective spin conductivity corresponding to the SOT turns out to be almost temperature-independent. Our results suggest that the charge-spin conversion in the chemical vapor deposition-grown large-scale monolayer TMDs could potentially lead to high energy efficiency for magnetization reversal and convenient device integration for future spintronics based on two-dimensional materials.
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Affiliation(s)
- Qiming Shao
- Device Research Laboratory, Department of Electrical Engineering, University of California , Los Angeles 90095, United States
| | - Guoqiang Yu
- Device Research Laboratory, Department of Electrical Engineering, University of California , Los Angeles 90095, United States
| | - Yann-Wen Lan
- Device Research Laboratory, Department of Electrical Engineering, University of California , Los Angeles 90095, United States
- National Nano Device Laboratories, Hsinchu 30078, Taiwan
| | - Yumeng Shi
- Physical Science and Engineering Division, King Abdullah University of Science and Technology , Thuwal 23955-6900, Kingdom of Saudi Arabia
- SZU-NUS Collaborative Innovation Center for Optoelectronic Science & Technology and Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education, College of Optoelectronic Engineering, Shenzhen University , Shenzhen 518060, China
| | - Ming-Yang Li
- Physical Science and Engineering Division, King Abdullah University of Science and Technology , Thuwal 23955-6900, Kingdom of Saudi Arabia
- Research Center for Applied Sciences, Academia Sinica , Taipei 10617, Taiwan
| | - Cheng Zheng
- Device Research Laboratory, Department of Electrical Engineering, University of California , Los Angeles 90095, United States
| | - Xiaodan Zhu
- Device Research Laboratory, Department of Electrical Engineering, University of California , Los Angeles 90095, United States
| | - Lain-Jong Li
- Physical Science and Engineering Division, King Abdullah University of Science and Technology , Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - Pedram Khalili Amiri
- Device Research Laboratory, Department of Electrical Engineering, University of California , Los Angeles 90095, United States
| | - Kang L Wang
- Device Research Laboratory, Department of Electrical Engineering, University of California , Los Angeles 90095, United States
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22
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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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23
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Han J, Wang Y, Pan F, Song C. Spin-Hall-Effect-Assisted Electroresistance in Antiferromagnets via 10(5) A/cm(2) dc Current. Sci Rep 2016; 6:31966. [PMID: 27546199 PMCID: PMC4992953 DOI: 10.1038/srep31966] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Accepted: 08/01/2016] [Indexed: 11/09/2022] Open
Abstract
Antiferromagnet (AFM) spintronics with reduced electrical current is greatly expected to process information with high integration and low power consumption. In Pt/FeMn and Ta/FeMn hybrids, we observe significant resistance variation (up to 7% of the total resistance) manipulated by 10(5) A/cm(2) dc current. We have excluded the contribution of isotropic structural effects, and confirmed the critical role of the spin Hall injection from Pt (or Ta) to FeMn. This electrical current-manipulated resistance (i.e. electroresistance) is proposed to be attributed to the spin-Hall-effect-induced spin-orbit torque in FeMn. Similar results have also been detected in plain IrMn films, where the charge current generates spin current via the spin Hall effect with the existence of Ir atoms. All the measurements are free from external magnetic fields and ferromagnets. Our findings present an interesting step towards high-efficiency spintronic devices.
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Affiliation(s)
- Jiahao Han
- Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
| | - Yuyan Wang
- Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
| | - Feng Pan
- Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
| | - Cheng Song
- Key Laboratory of Advanced Materials (MOE), School of Materials Science and Engineering, Tsinghua University, Beijing 100084, China
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24
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Saidaoui HBM, Manchon A. Spin-Swapping Transport and Torques in Ultrathin Magnetic Bilayers. PHYSICAL REVIEW LETTERS 2016; 117:036601. [PMID: 27472125 DOI: 10.1103/physrevlett.117.036601] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Indexed: 06/06/2023]
Abstract
Planar spin transport in disordered ultrathin magnetic bilayers comprising a ferromagnet and a normal metal (typically used for spin pumping, spin Seebeck and spin-orbit torque experiments) is investigated theoretically. Using a tight-binding model that puts the extrinsic spin Hall effect and spin swapping on equal footing, we show that the nature of spin-orbit coupled transport dramatically depends on the ratio between the layer thickness d and the mean free path λ. While the spin Hall effect dominates in the diffusive limit (d≫λ), spin swapping dominates in the Knudsen regime (d≲λ). A remarkable consequence is that spin swapping induces a substantial fieldlike torque in the Knudsen regime.
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Affiliation(s)
- Hamed Ben Mohamed Saidaoui
- Physical Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia
| | - A Manchon
- Physical Science and Engineering Division, King Abdullah University of Science and Technology (KAUST), Thuwal 23955-6900, Kingdom of Saudi Arabia
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25
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Fukami S, Anekawa T, Zhang C, Ohno H. A spin-orbit torque switching scheme with collinear magnetic easy axis and current configuration. NATURE NANOTECHNOLOGY 2016; 11:621-625. [PMID: 26999481 DOI: 10.1038/nnano.2016.29] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Accepted: 02/10/2016] [Indexed: 06/05/2023]
Abstract
Spin-orbit torque, a torque brought about by in-plane current via the spin-orbit interactions in heavy-metal/ferromagnet nanostructures, provides a new pathway to switch the magnetization direction. Although there are many recent studies, they all build on one of two structures that have the easy axis of a nanomagnet lying orthogonal to the current, that is, along the z or y axes. Here, we present a new structure with the third geometry, that is, with the easy axis collinear with the current (along the x axis). We fabricate a three-terminal device with a Ta/CoFeB/MgO-based stack and demonstrate the switching operation driven by the spin-orbit torque due to Ta with a negative spin Hall angle. Comparisons with different geometries highlight the previously unknown mechanisms of spin-orbit torque switching. Our work offers a new avenue for exploring the physics of spin-orbit torque switching and its application to spintronics devices.
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Affiliation(s)
- S Fukami
- Center for Spintronics Integrated Systems, Tohoku University, 2-1-1 Katahira, Aoba, Sendai 980-8577, Japan
- Center for Innovative Integrated Electronic Systems, Tohoku University, 468-1 Aoba, Aramaki, Aoba, Sendai 980-0845, Japan
| | - T Anekawa
- Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aoba, Sendai 980-8577, Japan
| | - C Zhang
- Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aoba, Sendai 980-8577, Japan
| | - H Ohno
- Center for Spintronics Integrated Systems, Tohoku University, 2-1-1 Katahira, Aoba, Sendai 980-8577, Japan
- Center for Innovative Integrated Electronic Systems, Tohoku University, 468-1 Aoba, Aramaki, Aoba, Sendai 980-0845, Japan
- Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aoba, Sendai 980-8577, Japan
- WPI Advanced Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba, Sendai 980 8577, Japan
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26
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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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27
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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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28
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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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29
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Nguyen MH, Ralph DC, Buhrman RA. Spin Torque Study of the Spin Hall Conductivity and Spin Diffusion Length in Platinum Thin Films with Varying Resistivity. PHYSICAL REVIEW LETTERS 2016; 116:126601. [PMID: 27058088 DOI: 10.1103/physrevlett.116.126601] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2015] [Indexed: 06/05/2023]
Abstract
We report measurements of the spin torque efficiencies in perpendicularly magnetized Pt/Co bilayers where the Pt resistivity ρ_{Pt} is strongly dependent on thickness t_{Pt}. The dampinglike spin Hall torque efficiency per unit current density ξ_{DL}^{j} varies significantly with t_{Pt}, exhibiting a peak value ξ_{DL}^{j}=0.12 at t_{Pt}=2.8-3.9 nm. In contrast, ξ_{DL}^{j}/ρ_{Pt} increases monotonically with t_{Pt} and saturates for t_{Pt}>5 nm, consistent with an intrinsic spin Hall effect mechanism, in which ξ_{DL}^{j} is enhanced by an increase in ρ_{Pt}. Assuming the Elliott-Yafet spin scattering mechanism dominates, we estimate that the spin diffusion length λ_{s}=(0.77±0.08)×10^{-15} Ω·m^{2}/ρ_{Pt}.
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Affiliation(s)
| | - D C Ralph
- Cornell University, Ithaca, New York 14853, USA
- Kavli Institute at Cornell, Ithaca, New York 14853, USA
| | - R A Buhrman
- Cornell University, Ithaca, New York 14853, USA
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30
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Spin-orbit torque in Pt/CoNiCo/Pt symmetric devices. Sci Rep 2016; 6:20778. [PMID: 26856379 PMCID: PMC4746736 DOI: 10.1038/srep20778] [Citation(s) in RCA: 83] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/30/2015] [Accepted: 01/12/2016] [Indexed: 11/18/2022] Open
Abstract
Current induced magnetization switching by spin-orbit torques offers an energy-efficient means of writing information in heavy metal/ferromagnet (FM) multilayer systems. The relative contributions of field-like torques and damping-like torques to the magnetization switching induced by the electrical current are still under debate. Here, we describe a device based on a symmetric Pt/FM/Pt structure, in which we demonstrate a strong damping-like torque from the spin Hall effect and unmeasurable field-like torque from Rashba effect. The spin-orbit effective fields due to the spin Hall effect were investigated quantitatively and were found to be consistent with the switching effective fields after accounting for the switching current reduction due to thermal fluctuations from the current pulse. A non-linear dependence of deterministic switching of average Mz on the in-plane magnetic field was revealed, which could be explained and understood by micromagnetic simulation.
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31
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Nonvolatile modulation of electronic structure and correlative magnetism of L10-FePt films using significant strain induced by shape memory substrates. Sci Rep 2016; 6:20199. [PMID: 26830325 PMCID: PMC4735331 DOI: 10.1038/srep20199] [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: 08/13/2015] [Accepted: 12/23/2015] [Indexed: 11/08/2022] Open
Abstract
Tuning the lattice strain (εL) is a novel approach to manipulate the magnetic, electronic, and transport properties of spintronic materials. Achievable εL in thin film samples induced by traditional ferroelectric or flexible substrates is usually volatile and well below 1%. Such limits in the tuning capability cannot meet the requirements for nonvolatile applications of spintronic materials. This study answers to the challenge of introducing significant amount of elastic strain in deposited thin films so that noticeable tuning of the spintronic characteristics can be realized. Based on subtle elastic strain engineering of depositing L10-FePt films on pre-stretched NiTi(Nb) shape memory alloy substrates, steerable and nonvolatile lattice strain up to 2.18% has been achieved in the L10-FePt films by thermally controlling the shape memory effect of the substrates. Introduced strains at this level significantly modify the electronic density of state, orbital overlap, and spin-orbit coupling (SOC) strength in the FePt film, leading to nonvolatile modulation of magnetic anisotropy and magnetization reversal characteristics. This finding not only opens an efficient avenue for the nonvolatile tuning of SOC based magnetism and spintronic effects, but also helps to clarify the physical nature of pure strain effect.
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32
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Yang L, Verba R, Tiberkevich V, Schneider T, Smith A, Duan Z, Youngblood B, Lenz K, Lindner J, Slavin AN, Krivorotov IN. Reduction of phase noise in nanowire spin orbit torque oscillators. Sci Rep 2015; 5:16942. [PMID: 26592432 PMCID: PMC4655334 DOI: 10.1038/srep16942] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2015] [Accepted: 10/22/2015] [Indexed: 11/09/2022] Open
Abstract
Spin torque oscillators (STOs) are compact, tunable sources of microwave radiation that serve as a test bed for studies of nonlinear magnetization dynamics at the nanometer length scale. The spin torque in an STO can be created by spin-orbit interaction, but low spectral purity of the microwave signals generated by spin orbit torque oscillators hinders practical applications of these magnetic nanodevices. Here we demonstrate a method for decreasing the phase noise of spin orbit torque oscillators based on Pt/Ni80Fe20 nanowires. We experimentally demonstrate that tapering of the nanowire, which serves as the STO active region, significantly decreases the spectral linewidth of the generated signal. We explain the observed linewidth narrowing in the framework of the Ginzburg-Landau auto-oscillator model. The model reveals that spatial non-uniformity of the spin current density in the tapered nanowire geometry hinders the excitation of higher order spin-wave modes, thus stabilizing the single-mode generation regime. This non-uniformity also generates a restoring force acting on the excited self-oscillatory mode, which reduces thermal fluctuations of the mode spatial position along the wire. Both these effects improve the STO spectral purity.
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Affiliation(s)
- Liu Yang
- Department of Physics and Astronomy, University of California, Irvine, CA 92697, USA
| | - Roman Verba
- Institute of Magnetism, National Academy of Sciences of Ukraine, Kyiv 03142, Ukraine
| | | | - Tobias Schneider
- Helmholtz-Zentrum Dresden - Rossendorf, Institute of Ion Beam Physics and Materials Research, Bautzner Landstraße 400, 01328 Dresden, Germany
| | - Andrew Smith
- Department of Physics and Astronomy, University of California, Irvine, CA 92697, USA
| | - Zheng Duan
- Department of Physics and Astronomy, University of California, Irvine, CA 92697, USA
| | - Brian Youngblood
- Department of Physics and Astronomy, University of California, Irvine, CA 92697, USA
| | - Kilian Lenz
- Helmholtz-Zentrum Dresden - Rossendorf, Institute of Ion Beam Physics and Materials Research, Bautzner Landstraße 400, 01328 Dresden, Germany
| | - Jürgen Lindner
- Helmholtz-Zentrum Dresden - Rossendorf, Institute of Ion Beam Physics and Materials Research, Bautzner Landstraße 400, 01328 Dresden, Germany
| | - Andrei N Slavin
- Department of Physics, Oakland University, Rochester, MI 48309, USA
| | - Ilya N Krivorotov
- Department of Physics and Astronomy, University of California, Irvine, CA 92697, USA
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33
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Large spin Hall magnetoresistance and its correlation to the spin-orbit torque in W/CoFeB/MgO structures. Sci Rep 2015; 5:14668. [PMID: 26423608 PMCID: PMC4589767 DOI: 10.1038/srep14668] [Citation(s) in RCA: 120] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Accepted: 09/03/2015] [Indexed: 11/24/2022] Open
Abstract
The phenomena based on spin-orbit interaction in heavy metal/ferromagnet/oxide structures have been investigated extensively due to their applicability to the manipulation of the magnetization direction via the in-plane current. This implies the existence of an inverse effect, in which the conductivity in such structures should depend on the magnetization orientation. In this work, we report a systematic study of the magnetoresistance (MR) of W/CoFeB/MgO structures and its correlation with the current-induced torque to the magnetization. We observe that the MR is independent of the angle between the magnetization and current direction but is determined by the relative magnetization orientation with respect to the spin direction accumulated by the spin Hall effect, for which the symmetry is identical to that of so-called the spin Hall magnetoresistance. The MR of ~1% in W/CoFeB/MgO samples is considerably larger than those in other structures of Ta/CoFeB/MgO or Pt/Co/AlOx, which indicates a larger spin Hall angle of W. Moreover, the similar W thickness dependence of the MR and the current-induced magnetization switching efficiency demonstrates that MR in a non-magnet/ferromagnet structure can be utilized to understand other closely correlated spin-orbit coupling effects such as the inverse spin Hall effect or the spin-orbit spin transfer torques.
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34
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Hupfauer T, Matos-Abiague A, Gmitra M, Schiller F, Loher J, Bougeard D, Back CH, Fabian J, Weiss D. Emergence of spin-orbit fields in magnetotransport of quasi-two-dimensional iron on gallium arsenide. Nat Commun 2015; 6:7374. [PMID: 26051594 PMCID: PMC4468871 DOI: 10.1038/ncomms8374] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Accepted: 04/29/2015] [Indexed: 11/17/2022] Open
Abstract
The desire for higher information capacities drives the components of electronic devices to ever smaller dimensions so that device properties are determined increasingly more by interfaces than by the bulk structure of the constituent materials. Spintronic devices, especially, benefit from the presence of interfaces—the reduced structural symmetry creates emergent spin–orbit fields that offer novel possibilities to control device functionalities. But where does the bulk end, and the interface begin? Here we trace the interface-to-bulk transition, and follow the emergence of the interfacial spin–orbit fields, in the conducting states of a few monolayers of iron on top of gallium arsenide. We observe the transition from the interface- to bulk-induced lateral crystalline magnetoanisotropy, each having a characteristic symmetry pattern, as the epitaxially grown iron channel increases from four to eight monolayers. Setting the upper limit on the width of the interface-imprinted conducting channel is an important step towards an active control of interfacial spin–orbit fields. Broken symmetry at material interfaces allows for novel spintronic functionality via emergent spin–orbit effects. Here, Hupfauer et al. follow the interface-to-bulk transition of ultra-thin epitaxial iron films on gallium arsenide via anisotropic magnetoresistance measurements and first-principle calculations.
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Affiliation(s)
- T Hupfauer
- Institute of Experimental and Applied Physics, University of Regensburg, 93040 Regensburg, Germany
| | - A Matos-Abiague
- Institute of Theoretical Physics, University of Regensburg, 93040 Regensburg, Germany
| | - M Gmitra
- Institute of Theoretical Physics, University of Regensburg, 93040 Regensburg, Germany
| | - F Schiller
- Institute of Experimental and Applied Physics, University of Regensburg, 93040 Regensburg, Germany
| | - J Loher
- Institute of Experimental and Applied Physics, University of Regensburg, 93040 Regensburg, Germany
| | - D Bougeard
- Institute of Experimental and Applied Physics, University of Regensburg, 93040 Regensburg, Germany
| | - C H Back
- Institute of Experimental and Applied Physics, University of Regensburg, 93040 Regensburg, Germany
| | - J Fabian
- Institute of Theoretical Physics, University of Regensburg, 93040 Regensburg, Germany
| | - D Weiss
- Institute of Experimental and Applied Physics, University of Regensburg, 93040 Regensburg, Germany
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35
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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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36
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Ciccarelli C, Hals KMD, Irvine A, Novak V, Tserkovnyak Y, Kurebayashi H, Brataas A, Ferguson A. Magnonic charge pumping via spin-orbit coupling. NATURE NANOTECHNOLOGY 2015; 10:50-54. [PMID: 25383512 DOI: 10.1038/nnano.2014.252] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2014] [Accepted: 10/01/2014] [Indexed: 06/04/2023]
Abstract
The interplay between spin, charge and orbital degrees of freedom has led to the development of spintronic devices such as spin-torque oscillators and spin-transfer torque magnetic random-access memories. In this development, spin pumping represents a convenient way to electrically detect magnetization dynamics. The effect originates from direct conversion of low-energy quantized spin waves in the magnet, known as magnons, into a flow of spins from the precessing magnet to adjacent leads. In this case, a secondary spin-charge conversion element, such as heavy metals with large spin Hall angle or multilayer layouts, is required to convert the spin current into a charge signal. Here, we report the experimental observation of charge pumping in which a precessing ferromagnet pumps a charge current, demonstrating direct conversion of magnons into high-frequency currents via the relativistic spin-orbit interaction. The generated electric current, unlike spin currents generated by spin-pumping, can be directly detected without the need of any additional spin-charge conversion mechanism. The charge-pumping phenomenon is generic and gives a deeper understanding of its reciprocal effect, the spin orbit torque, which is currently attracting interest for their potential in manipulating magnetic information.
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Affiliation(s)
- Chiara Ciccarelli
- Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, UK
| | - Kjetil M D Hals
- 1] Department of Physics, Norwegian University of Science and Technology, NO-7491, Trondheim, Norway [2] Niels Bohr International Academy and the Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
| | - Andrew Irvine
- Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, UK
| | - Vit Novak
- Institute of Physics ASCR, v.v.i., Cukrovarnická 10, 162 53 Praha 6, Czech Republic
| | - Yaroslav Tserkovnyak
- Department of Physics and Astronomy, University of California, Los Angeles, California 90095, USA
| | - Hidekazu Kurebayashi
- 1] Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, UK [2] PRESTO, Japan Science and Technology Agency, Kawaguchi 332-0012, Japan
| | - Arne Brataas
- Department of Physics, Norwegian University of Science and Technology, NO-7491, Trondheim, Norway
| | - Andrew Ferguson
- Cavendish Laboratory, University of Cambridge, Cambridge CB3 0HE, UK
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37
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Nanowire spin torque oscillator driven by spin orbit torques. Nat Commun 2014; 5:5616. [DOI: 10.1038/ncomms6616] [Citation(s) in RCA: 151] [Impact Index Per Article: 15.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Accepted: 10/21/2014] [Indexed: 11/08/2022] Open
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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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Mellnik AR, Lee JS, Richardella A, Grab JL, Mintun PJ, Fischer MH, Vaezi A, Manchon A, Kim EA, Samarth N, Ralph DC. Spin-transfer torque generated by a topological insulator. Nature 2014; 511:449-51. [DOI: 10.1038/nature13534] [Citation(s) in RCA: 945] [Impact Index Per Article: 94.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2014] [Accepted: 05/27/2014] [Indexed: 11/09/2022]
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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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Affiliation(s)
- Arne Brataas
- Department of Physics, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
| | - Kjetil M D Hals
- Department of Physics, Norwegian University of Science and Technology, NO-7491 Trondheim, Norway
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Quantifying interface and bulk contributions to spin–orbit torque in magnetic bilayers. Nat Commun 2014; 5:3042. [DOI: 10.1038/ncomms4042] [Citation(s) in RCA: 235] [Impact Index Per Article: 23.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2013] [Accepted: 12/02/2013] [Indexed: 11/08/2022] Open
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Jamali M, Narayanapillai K, Qiu X, Loong LM, Manchon A, Yang H. Spin-orbit torques in Co/Pd multilayer nanowires. PHYSICAL REVIEW LETTERS 2013; 111:246602. [PMID: 24483683 DOI: 10.1103/physrevlett.111.246602] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Revised: 10/23/2013] [Indexed: 06/03/2023]
Abstract
Current induced spin-orbit torques have been studied in ferromagnetic nanowires made of 20 nm thick Co/Pd multilayers with perpendicular magnetic anisotropy. Using Hall voltage and lock-in measurements, it is found that upon injection of an electric current both in-plane (Slonczewski-like) and perpendicular (fieldlike) torques build up in the nanowire. The torque efficiencies are found to be as large as 1.17 and 5 kOe at 10(8) A/cm2 for the in-plane and perpendicular components, respectively, which is surprisingly comparable to previous studies in ultrathin (∼1 nm) magnetic bilayers. We show that this result cannot be explained solely by spin Hall effect induced torque at the outer interfaces, indicating a probable contribution of the bulk of the Co/Pd multilayer.
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Affiliation(s)
- Mahdi Jamali
- Department of Electrical and Computer Engineering and NUSNNI, National University of Singapore, 117576 Singapore, Singapore
| | | | - Xuepeng Qiu
- Department of Electrical and Computer Engineering and NUSNNI, National University of Singapore, 117576 Singapore, Singapore
| | - Li Ming Loong
- Department of Electrical and Computer Engineering and NUSNNI, National University of Singapore, 117576 Singapore, 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, 117576 Singapore, Singapore
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