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Kitaori A, White JS, Ukleev V, Peng L, Nakajima K, Kanazawa N, Yu X, Ōnuki Y, Tokura Y. Enhanced emergent electromagnetic inductance in Tb 5Sb 3 due to highly disordered helimagnetism. COMMUNICATIONS PHYSICS 2024; 7:159. [PMID: 38779470 PMCID: PMC11106002 DOI: 10.1038/s42005-024-01656-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 12/23/2023] [Accepted: 05/08/2024] [Indexed: 05/25/2024]
Abstract
In helimagnetic metals, ac current-driven spin motions can generate emergent electric fields acting on conduction electrons, leading to emergent electromagnetic induction (EEMI). Recent experiments reveal the EEMI signal generally shows a strongly current-nonlinear response. In this study, we investigate the EEMI of Tb5Sb3, a short-period helimagnet. Using small angle neutron scattering we show that Tb5Sb3 hosts highly disordered helimagnetism with a distribution of spin-helix periodicity. The current-nonlinear dynamics of the disordered spin helix in Tb5Sb3 indeed shows up as the nonlinear electrical resistivity (real part of ac resistivity), and even more clearly as a nonlinear and huge EEMI (imaginary part of ac resistivity) response. The magnitude of the EEMI reaches as large as several tens of μH for Tb5Sb3 devices on the scale of several tens of μm, originating to noncollinear spin textures possibly even without long-range helimagnetic order.
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Affiliation(s)
- Aki Kitaori
- Institute of Engineering Innovation, The University of Tokyo, Tokyo, 113-0032 Japan
- Department of Applied Physics, The University of Tokyo, Tokyo, 113-8656 Japan
- RIKEN Center for Emergent Matter Science (CEMS), Wako, 351-0198 Japan
| | - Jonathan S. White
- Laboratory for Neutron Scattering and Imaging (LNS), Paul Scherrer Institute (PSI), CH-5232 Villigen, Switzerland
| | - Victor Ukleev
- Laboratory for Neutron Scattering and Imaging (LNS), Paul Scherrer Institute (PSI), CH-5232 Villigen, Switzerland
- Helmholtz-Zentrum Berlin für Materialien und Energie, D-14109 Berlin, Germany
| | - Licong Peng
- RIKEN Center for Emergent Matter Science (CEMS), Wako, 351-0198 Japan
| | - Kiyomi Nakajima
- RIKEN Center for Emergent Matter Science (CEMS), Wako, 351-0198 Japan
| | - Naoya Kanazawa
- Institute of Industrial Science, The University of Tokyo, Tokyo, 153-8505 Japan
| | - Xiuzhen Yu
- RIKEN Center for Emergent Matter Science (CEMS), Wako, 351-0198 Japan
| | - Yoshichika Ōnuki
- RIKEN Center for Emergent Matter Science (CEMS), Wako, 351-0198 Japan
| | - Yoshinori Tokura
- Department of Applied Physics, The University of Tokyo, Tokyo, 113-8656 Japan
- RIKEN Center for Emergent Matter Science (CEMS), Wako, 351-0198 Japan
- Tokyo College, The University of Tokyo, Tokyo, 113-8656 Japan
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2
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Oh T, Nagaosa N. Emergent Inductance from Spin Fluctuations in Strongly Correlated Magnets. PHYSICAL REVIEW LETTERS 2024; 132:116501. [PMID: 38563933 DOI: 10.1103/physrevlett.132.116501] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Revised: 02/16/2024] [Accepted: 02/22/2024] [Indexed: 04/04/2024]
Abstract
Recently, the intriguing phenomenon of emergent inductance has been theoretically proposed and experimentally observed in nanoscale spiral spin systems subjected to oscillating currents. Building upon these recent developments, we put forward the concept of emergent inductance in strongly correlated magnets in the normal state with spin fluctuations. It is argued that the inductance shows a positive peak at temperatures above the ordering temperature. As for the frequency dependence, in systems featuring a single-band structure or a gapped multiband, we observe a Drude-type inductance, while in gapless multiband systems, a non-Drude inductance with a sharp dip near zero frequency. These results offer valuable insights into the behavior of strongly correlated magnets and open up new possibilities for harnessing emergent inductance in practical applications.
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Affiliation(s)
- Taekoo Oh
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan
| | - Naoto Nagaosa
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan
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3
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Tchernyshyov O. Unified theory of spin and charge in a ferromagnet. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 51:014001. [PMID: 36301718 DOI: 10.1088/1361-648x/ac9dd9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2022] [Accepted: 10/26/2022] [Indexed: 06/16/2023]
Abstract
We derive a unified theory of spin and charge degrees of freedom in a ferromagnet. The spin-transfer torque and spin electromotive force are examined from the coarse-grained perspective of collective coordinates. The resulting equations of motion reflect a balance of conservative, gyroscopic (Berry-phase), and dissipative forces. We then expand the space of collective coordinates by adding the electric charge. The adiabatic spin-transfer torque and spin electromotive force (emf) turn out to be a gyroscopic force; their nonadiabatic counterparts are a dissipative force.
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Affiliation(s)
- Oleg Tchernyshyov
- William H Miller III Department of Physics and Astronomy and Institute for Quantum Matter, Johns Hopkins University, Baltimore, MD 21218, United States of America
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Bobkova IV, Bobkov AM, Silaev MA. Magnetoelectric effects in Josephson junctions. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:353001. [PMID: 35709718 DOI: 10.1088/1361-648x/ac7994] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2021] [Accepted: 06/16/2022] [Indexed: 06/15/2023]
Abstract
The review is devoted to the fundamental aspects and characteristic features of the magnetoelectric effects, reported in the literature on Josephson junctions (JJs). The main focus of the review is on the manifestations of the direct and inverse magnetoelectric effects in various types of Josephson systems. They provide a coupling of the magnetization in superconductor/ferromagnet/superconductor JJs to the Josephson current. The direct magnetoelectric effect is a driving force of spin torques acting on the ferromagnet inside the JJ. Therefore it is of key importance for the electrical control of the magnetization. The inverse magnetoelectric effect accounts for the back action of the magnetization dynamics on the Josephson subsystem, in particular, making the JJ to be in the resistive state in the presence of the magnetization dynamics of any origin. The perspectives of the coupling of the magnetization in JJs with ferromagnetic interlayers to the Josephson current via the magnetoelectric effects are discussed.
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Affiliation(s)
- I V Bobkova
- Institute of Solid State Physics, Chernogolovka, Moscow Region 142432, Russia
- Moscow Institute of Physics and Technology, Dolgoprudny 141700, Russia
- National Research University Higher School of Economics, Moscow 101000, Russia
| | - A M Bobkov
- Institute of Solid State Physics, Chernogolovka, Moscow Region 142432, Russia
- Moscow Institute of Physics and Technology, Dolgoprudny 141700, Russia
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5
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Yamane Y, Fukami S, Ieda J. Theory of Emergent Inductance with Spin-Orbit Coupling Effects. PHYSICAL REVIEW LETTERS 2022; 128:147201. [PMID: 35476473 DOI: 10.1103/physrevlett.128.147201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 12/23/2021] [Accepted: 02/25/2022] [Indexed: 06/14/2023]
Abstract
We extend the theory of emergent inductance, which has recently been discovered in spiral magnets, to arbitrary magnetic textures by taking into account spin-orbit couplings arising in the absence of spatial inversion symmetry. We propose a new concept of spin-orbit emergent inductance, which can be formulated as originating from a dynamical Aharonov-Casher phase of an electron in ferromagnets. The spin-orbit emergent inductance universally arises in the coexistence of magnetism and the spin-orbit couplings, even with spatially uniform magnetization, allowing its stable operation in wide ranges of temperature and frequency. Revisiting the widely studied systems involving ferromagnets with spatial inversion asymmetry, with the new perspective offered by our work, will lead to opening a new paradigm in the study of spin-orbit physics and the spintronics-based power management in ultrawideband frequency range.
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Affiliation(s)
- Yuta Yamane
- Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, Sendai 980-8578, Japan
- Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577, Japan
| | - Shunsuke Fukami
- Research Institute of Electrical Communication, Tohoku University, Sendai 980-8577, Japan
- Center for Spintronics Research Network, Tohoku University, Sendai 980-8577, Japan
- Center for Science and Innovation in Spintronics, Tohoku University, Sendai 980-8577, Japan
- Center for Innovative Integrated Electronic Systems, Tohoku University, Sendai 980-0845, Japan
- WPI-Advanced Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - Jun'ichi Ieda
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai 319-1195, Japan
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6
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Funato T, Matsuo M. Spin Elastodynamic Motive Force. PHYSICAL REVIEW LETTERS 2022; 128:077201. [PMID: 35244426 DOI: 10.1103/physrevlett.128.077201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 11/30/2021] [Accepted: 01/20/2022] [Indexed: 06/14/2023]
Abstract
The spin-motive force (SMF) in a simple ferromagnetic monolayer caused by a surface acoustic wave is studied theoretically via spin-vorticity coupling (SVC). The SMF has two mechanisms. The first is the SVC-driven SMF, which produces the first harmonic electromotive force, and the second is the interplay between the SVC and the magnetoelastic coupling, which produces the dc and second harmonic electromotive forces. We show that these electric voltages induced by a Rayleigh-type surface acoustic wave can be detected in polycrystalline nickel. No sophisticated device structures, noncollinear magnetic structures, or strong spin-orbit materials are used in our approach. Consequently, it is intended to broaden the spectrum of SMF applications considerably.
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Affiliation(s)
- Takumi Funato
- Center for Spintronics Research Network, Keio University, Yokohama 223-8522, Japan
- Kavli Institute for Theoretical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
| | - Mamoru Matsuo
- Kavli Institute for Theoretical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100190, China
- RIKEN Center for Emergent Matter Science (CEMS), Wako, Saitama 351-0198, Japan
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai 319-1195, Japan
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7
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Abstract
Emergent electromagnetic induction based on electrodynamics of noncollinear spin states may enable dramatic miniaturization of inductor elements widely used in electric circuits, yet the research is still in its infancy and many issues must be resolved toward its application. One such problem is how to increase working temperature to room temperature, and possible thermal agitation effects on the quantum process of the emergent induction are unknown. We report here large emergent electromagnetic induction achieved around and above room temperature, making use of a few tens of micrometer-sized devices based on the high-temperature (up to 330 K) and short-period (≤ 3 nm) spin-spiral states of a metallic helimagnet. The observed inductance value L and its sign are observed to vary to a large extent, depending not only on the spin-helix structure controlled by temperature and applied magnetic field but also on the applied current density. The present finding on room-temperature operation and possible sign control of L may provide a step toward realizing microscale quantum inductors on the basis of emergent electromagnetism in spin-helix states.
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Abstract
Skyrmion, a concept originally proposed in particle physics half a century ago, can now find the most fertile field for its applicability, that is, the magnetic skyrmion realized in helimagnetic materials. The spin swirling vortex-like texture of the magnetic skyrmion can define the particle nature by topology; that is, all the constituent spin moments within the two-dimensional sheet wrap the sphere just one time. Such a topological nature of the magnetic skyrmion can lead to extraordinary metastability via topological protection and the driven motion with low electric-current excitation, which may promise future application to spintronics. The skyrmions in the magnetic materials frequently show up as the crystal lattice form, e.g., hexagonal lattice, but sometimes as isolated or independent particles. These skyrmions in magnets were initially found in acentric magnets, such as chiral, polar, and bilayered magnets endowed with antisymmetric spin exchange interaction, while the skyrmion host materials have been explored in a broader family of compounds including centrosymmetric magnets. This review describes the materials science and materials chemistry of magnetic skyrmions using the classification scheme of the skyrmion forming microscopic mechanisms. The emergent phenomena and functions mediated by skyrmions are described, including the generation of emergent magnetic and electric field by statics and dynamics of skrymions and the inherent magnetoelectric effect. The other important magnetic topological defects in two or three dimensions, such as biskyrmions, antiskyrmions, merons, and hedgehogs, are also reviewed in light of their interplay with the skyrmions.
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Affiliation(s)
- Yoshinori Tokura
- Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan.,RIKEN Center for Emergent Matter Science (CEMS), Wako, 351-0198, Japan.,Tokyo College, University of Tokyo, Tokyo 113-8656, Japan
| | - Naoya Kanazawa
- Department of Applied Physics, University of Tokyo, Tokyo 113-8656, Japan
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9
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Emergent electromagnetic induction in a helical-spin magnet. Nature 2020; 586:232-236. [PMID: 33029000 DOI: 10.1038/s41586-020-2775-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2020] [Accepted: 08/04/2020] [Indexed: 11/08/2022]
Abstract
An inductor, one of the most fundamental circuit elements in modern electronic devices, generates a voltage proportional to the time derivative of the input current1. Conventional inductors typically consist of a helical coil and induce a voltage as a counteraction to time-varying magnetic flux penetrating the coil, following Faraday's law of electromagnetic induction. The magnitude of this conventional inductance is proportional to the volume of the inductor's coil, which hinders the miniaturization of inductors2. Here, we demonstrate an inductance of quantum-mechanical origin3, generated by the emergent electric field induced by current-driven dynamics of spin helices in a magnet. In microscale rectangular magnetic devices with nanoscale spin helices, we observe a typical inductance as large as -400 nanohenry, comparable in magnitude to that of a commercial inductor, but in a volume about a million times smaller. The observed inductance is enhanced by nonlinearity in current and shows non-monotonous frequency dependence, both of which result from the current-driven dynamics of the spin-helix structures. The magnitude of the inductance rapidly increases with decreasing device cross-section, in contrast to conventional inductors. Our findings may pave the way to microscale, simple-shaped inductors based on emergent electromagnetism related to the quantum-mechanical Berry phase.
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Shukla AS, Chouhan A, Pandey R, Raghupathi M, Yamamoto T, Kubota H, Fukushima A, Yuasa S, Nozaki T, Tulapurkar AA. Generation of charge current from magnetization oscillation via the inverse of voltage-controlled magnetic anisotropy effect. SCIENCE ADVANCES 2020; 6:eabc2618. [PMID: 32821845 PMCID: PMC7406361 DOI: 10.1126/sciadv.abc2618] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/15/2020] [Accepted: 06/18/2020] [Indexed: 06/11/2023]
Abstract
It is well known that oscillating magnetization induces charge current in a circuit via Faraday's law of electromagnetic induction. New physical phenomena by which magnetization dynamics can produce charge current have gained considerable interest recently. For example, moving magnetization textures, such as domain walls, generates charge current through the spin-motive force. Here, we examine an entirely different effect, which couples magnetization and electric field at the interface between an ultrathin metallic ferromagnet and dielectric. We show that this coupling can convert magnetic energy into electrical energy. This phenomenon is the Onsager reciprocal of the voltage-controlled magnetic anisotropy effect. The effect provides a previously unexplored probe to measure the magnetization dynamics of nanomagnets.
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Affiliation(s)
- Ambika Shanker Shukla
- Solid State Devices Group, Department of Electrical Engineering, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Akanksha Chouhan
- Solid State Devices Group, Department of Electrical Engineering, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Rachit Pandey
- Solid State Devices Group, Department of Electrical Engineering, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - M. Raghupathi
- Solid State Devices Group, Department of Electrical Engineering, Indian Institute of Technology Bombay, Mumbai 400076, India
| | - Tatsuya Yamamoto
- Spintronics Research Center, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8568, Japan
| | - Hitoshi Kubota
- Spintronics Research Center, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8568, Japan
| | - Akio Fukushima
- Spintronics Research Center, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8568, Japan
| | - Shinji Yuasa
- Spintronics Research Center, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8568, Japan
| | - Takayuki Nozaki
- Spintronics Research Center, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8568, Japan
| | - Ashwin A. Tulapurkar
- Solid State Devices Group, Department of Electrical Engineering, Indian Institute of Technology Bombay, Mumbai 400076, India
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11
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Rabinovich DS, Bobkova IV, Bobkov AM, Silaev MA. Resistive State of Superconductor-Ferromagnet-Superconductor Josephson Junctions in the Presence of Moving Domain Walls. PHYSICAL REVIEW LETTERS 2019; 123:207001. [PMID: 31809065 DOI: 10.1103/physrevlett.123.207001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 08/28/2019] [Indexed: 06/10/2023]
Abstract
We describe resistive states of the system combining two types of orderings-a superconducting and a ferromagnetic one. It is shown that in the presence of magnetization dynamics such systems become inherently dissipative and in principle cannot sustain any amount of the superconducting current because of the voltage generated by the magnetization dynamics. We calculate generic current-voltage characteristics of a superconductor-ferromagnet-superconductor Josephson junction with an unpinned domain wall and find the low-current resistance associated with the domain wall motion. We suggest the finite slope of Shapiro steps as the characteristic feature of the regime with domain wall oscillations driven by the ac external current flowing through the junction.
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Affiliation(s)
- D S Rabinovich
- Moscow Institute of Physics and Technology, Dolgoprudny, 141700 Russia
- Skolkovo Institute of Science and Technology, Skolkovo 143026, Russia
- Institute of Solid State Physics, Chernogolovka, Moscow reg., 142432 Russia
| | - I V Bobkova
- Moscow Institute of Physics and Technology, Dolgoprudny, 141700 Russia
- Institute of Solid State Physics, Chernogolovka, Moscow reg., 142432 Russia
| | - A M Bobkov
- Institute of Solid State Physics, Chernogolovka, Moscow reg., 142432 Russia
| | - M A Silaev
- Moscow Institute of Physics and Technology, Dolgoprudny, 141700 Russia
- Department of Physics and Nanoscience Center, University of Jyväskylä, P.O. Box 35 (YFL), FI-40014 University of Jyväskylä, Finland
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12
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Abbout A, Weston J, Waintal X, Manchon A. Cooperative Charge Pumping and Enhanced Skyrmion Mobility. PHYSICAL REVIEW LETTERS 2018; 121:257203. [PMID: 30608824 DOI: 10.1103/physrevlett.121.257203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/05/2018] [Indexed: 06/09/2023]
Abstract
It is well known that moving magnetic textures may pump spin and charge currents along the direction of motion, a phenomenon called electronic pumping. Here, the electronic pumping arising from the steady motion of ferromagnetic skyrmions is investigated by solving the time evolution of the Schrödinger equation implemented on a tight-binding model with the statistical physics of the many-body problem. In contrast with rigid one-dimensional magnetic textures, we show that steadily moving magnetic skyrmions are able to pump large dc currents. This ability arises from their nontrivial magnetic topology, i.e., the coexistence of the spin-motive force and the topological Hall effect. Based on an adiabatic scattering theory, we compute the pumped current and demonstrate that it scales with the reflection coefficient of the conduction electrons against the skyrmion. In other words, in the semiclassical limit, reducing the size of the skyrmion and the width of the nanowire enhances this effect, making it scalable. We propose that such a phenomenon can be exploited in the context of racetrack devices, where the electronic pumping enhances the collective motion of the train of skyrmions.
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Affiliation(s)
- Adel Abbout
- King Abdullah University of Science and Technology (KAUST), Physical Science and Engineering Division, Thuwal 23955-6900, Saudi Arabia
| | - Joseph Weston
- University Grenoble Alpes, INAC-PHELIQS, F-38000 Grenoble, France and CEA, INAC-PHELIQS, F-38000 Grenoble, France
| | - Xavier Waintal
- University Grenoble Alpes, INAC-PHELIQS, F-38000 Grenoble, France and CEA, INAC-PHELIQS, F-38000 Grenoble, France
| | - Aurélien Manchon
- King Abdullah University of Science and Technology (KAUST), Physical Science and Engineering Division, Thuwal 23955-6900, Saudi Arabia
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Ho CS, Tan SG, Shen SQ, Jalil MBA. Newton's second law in spin-orbit torque. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2018; 30:395301. [PMID: 30129927 DOI: 10.1088/1361-648x/aadbdd] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Spin-orbit torque (SOT) refers to the excitation of magnetization dynamics via spin-orbit coupling (SOC) under the application of a charged current. In this work, we introduce a simple and intuitive description of the SOT in terms of spin force. In Rashba SOC system, the damping-like SOT can be expressed as [Formula: see text], in analogy to the classical torque-force relation, where R c is the effective radius characterizing the Rashba splitting in the momentum space. As a consequence, the magnetic energy is transferred to the conduction electrons, which dissipates through Joule heating at a rate of [Formula: see text], with j e being the applied current. Finally, we propose an experimental verification of our findings via measurement of the anisotropic magnetoresistance effect.
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Affiliation(s)
- Cong Son Ho
- Department of Electrical and Computer Engineering, National University of Singapore, 4 Engineering Drive 3, 117576, Singapore
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Tserkovnyak Y, Xiao J. Energy Storage via Topological Spin Textures. PHYSICAL REVIEW LETTERS 2018; 121:127701. [PMID: 30296130 DOI: 10.1103/physrevlett.121.127701] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/04/2018] [Revised: 06/23/2018] [Indexed: 06/08/2023]
Abstract
We formulate an energy-storage concept based on the free energy associated with metastable magnetic configurations. Despite the active magnetic region of the battery being electrically insulating, it can sustain effective hydrodynamics of spin textures, whose conservation law is governed by topology. To illustrate the key physics and potential functionality, we focus here on the simplest quasi-one-dimensional case of planar winding of the magnetic order parameter. The energy is stored in the metastable winding number, which can be injected electrically by an appropriately tailored spin torque. Because of the nonvolatility and the endurance of magnetic systems, the injected energy can be stored essentially indefinitely, with the topological charge cycles that do not degrade over time.
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Affiliation(s)
- Yaroslav Tserkovnyak
- Department of Physics and Astronomy, University of California, Los Angeles, California 90095, USA
| | - Jiang Xiao
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Institute for Nanoelectronics Devices and Quantum Computing, Fudan University, Shanghai 200433, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
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15
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Al Gizi AJH. A particle swarm optimization, fuzzy PID controller with generator automatic voltage regulator. Soft comput 2018. [DOI: 10.1007/s00500-018-3483-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022]
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16
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Akosa CA, Tretiakov OA, Tatara G, Manchon A. Theory of the Topological Spin Hall Effect in Antiferromagnetic Skyrmions: Impact on Current-Induced Motion. PHYSICAL REVIEW LETTERS 2018; 121:097204. [PMID: 30230873 DOI: 10.1103/physrevlett.121.097204] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2017] [Revised: 05/11/2018] [Indexed: 06/08/2023]
Abstract
We demonstrate that the nontrivial magnetic texture of antiferromagnetic Skyrmions (AFM Sks) promotes a nonvanishing topological spin Hall effect (TSHE) on the flowing electrons. This effect results in a substantial enhancement of the nonadiabatic torque and, hence, improves the Skyrmion mobility. This nonadiabatic torque increases when decreasing the Skyrmion size, and, therefore, scaling down results in a much higher torque efficiency. In clean AFM Sks, we find a significant boost of the TSHE close to the van Hove singularity. Interestingly, this effect is enhanced away from the band gap in the presence of nonmagnetic interstitial defects. Furthermore, unlike their ferromagnetic counterpart, the TSHE in AFM Sks increases with an increase in the disorder strength, thus opening promising avenues for materials engineering of this effect.
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Affiliation(s)
- C A Akosa
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- King Abdullah University of Science and Technology (KAUST), Physical Science and Engineering (PSE) Division, Thuwal 23955-6900, Saudi Arabia
| | - O A Tretiakov
- Institute for Materials Research, Tohoku University, Sendai 980-8577, Japan
| | - G Tatara
- RIKEN Center for Emergent Matter Science (CEMS), 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- RIKEN Cluster for Pioneering Research (CPR), 2-1 Hirosawa, Wako, Saitama, 351-0198 Japan
| | - A Manchon
- King Abdullah University of Science and Technology (KAUST), Physical Science and Engineering (PSE) Division, Thuwal 23955-6900, Saudi Arabia
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17
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Kim SK, Tserkovnyak Y. Magnetic Domain Walls as Hosts of Spin Superfluids and Generators of Skyrmions. PHYSICAL REVIEW LETTERS 2017; 119:047202. [PMID: 29341776 DOI: 10.1103/physrevlett.119.047202] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Indexed: 06/07/2023]
Abstract
A domain wall in a magnet with easy-axis anisotropy is shown to harbor spin superfluid associated with its spontaneous breaking of the U(1) spin-rotational symmetry. The spin superfluid is shown to have several topological properties, which are absent in conventional superfluids. First, the associated phase slips create and destroy Skyrmions to obey the conservation of the total Skyrmion charge, which allows us to use a domain wall as a generator and detector of Skyrmions. Second, the domain wall engenders the emergent magnetic flux for magnons along its length, which are proportional to the spin supercurrent flowing through it, and thereby provides a way to manipulate magnons. Third, the spin supercurrent can be driven by the magnon current traveling across it owing to the spin transfer between the domain wall and magnons, leading to the magnonic manipulation of the spin superfluid. The theory for superfluid spin transport within the domain wall is confirmed by numerical simulations.
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Affiliation(s)
- Se Kwon Kim
- Department of Physics and Astronomy, University of California, Los Angeles, California 90095, USA
| | - Yaroslav Tserkovnyak
- Department of Physics and Astronomy, University of California, Los Angeles, California 90095, USA
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Kanazawa N, Seki S, Tokura Y. Noncentrosymmetric Magnets Hosting Magnetic Skyrmions. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2017; 29:1603227. [PMID: 28306166 DOI: 10.1002/adma.201603227] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/20/2016] [Revised: 11/30/2016] [Indexed: 06/06/2023]
Abstract
The concept of a skyrmion, which was first introduced by Tony Skyrme in the field of particle physics, has become widespread in condensed matter physics to describe various topological orders. Skyrmions in magnetic materials have recently received particular attention; they represent vortex-like spin structures with the character of nanometric particles and produce fascinating physical properties rooted in their topological nature. Here, a series of noncentrosymmetric ferromagnets hosting skyrmions is reviewed: B20 metals, Cu2 OSeO3 , Co-Zn-Mn alloys, and GaV4 S8 , where Dzyaloshinskii-Moriya interaction plays a key role in the stabilization of skyrmion spin texture. Their topological spin arrangements and consequent emergent electromagnetic fields give rise to striking features in transport and magnetoelectric properties in metals and insulators, such as the topological Hall effect, efficient electric-drive of skyrmions, and multiferroic behavior. Such electric controllability and nanometric particle natures highlight magnetic skyrmions as a potential information carrier for high-density magnetic storage devices with excellent energy efficiency.
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Affiliation(s)
- Naoya Kanazawa
- Department of Applied Physics, University of Tokyo, Tokyo, 113-8656, Japan
| | - Shinichiro Seki
- RIKEN Center for Emergent Matter Science (CEMS), Wako, 351-0198, Japan
| | - Yoshinori Tokura
- Department of Applied Physics, University of Tokyo, Tokyo, 113-8656, Japan
- RIKEN Center for Emergent Matter Science (CEMS), Wako, 351-0198, Japan
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19
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Bisig A, Akosa CA, Moon JH, Rhensius J, Moutafis C, von Bieren A, Heidler J, Kiliani G, Kammerer M, Curcic M, Weigand M, Tyliszczak T, Van Waeyenberge B, Stoll H, Schütz G, Lee KJ, Manchon A, Kläui M. Enhanced Nonadiabaticity in Vortex Cores due to the Emergent Hall Effect. PHYSICAL REVIEW LETTERS 2016; 117:277203. [PMID: 28084754 DOI: 10.1103/physrevlett.117.277203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2015] [Indexed: 06/06/2023]
Abstract
We present a combined theoretical and experimental study, investigating the origin of the enhanced nonadiabaticity of magnetic vortex cores. Scanning transmission x-ray microscopy is used to image the vortex core gyration dynamically to measure the nonadiabaticity with high precision, including a high confidence upper bound. We show theoretically, that the large nonadiabaticity parameter observed experimentally can be explained by the presence of local spin currents arising from a texture induced emergent Hall effect. This study demonstrates that the magnetic damping α and nonadiabaticity parameter β are very sensitive to the topology of the magnetic textures, resulting in an enhanced ratio (β/α>1) in magnetic vortex cores or Skyrmions.
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Affiliation(s)
- André Bisig
- Department of Physics, University of Konstanz, 78457 Konstanz, Germany
- Max Planck Institute for Intelligent Systems, 70569 Stuttgart, Germany
- Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
- Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
- Institut of Physics, Johannes Gutenberg University Mainz, 55099 Mainz, Germany
| | - Collins Ashu Akosa
- King Abdullah University of Science and Technology (KAUST), Physical Science and Engineering Division, Thuwal 23955-6900, Saudi Arabia
| | - Jung-Hwan Moon
- Department of Materials Science and Engineering, Korea University, Seoul 136-713, Korea
| | - Jan Rhensius
- Department of Physics, University of Konstanz, 78457 Konstanz, Germany
- Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Christoforos Moutafis
- Department of Physics, University of Konstanz, 78457 Konstanz, Germany
- Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
- Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Arndt von Bieren
- Department of Physics, University of Konstanz, 78457 Konstanz, Germany
- Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
- Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Jakoba Heidler
- Department of Physics, University of Konstanz, 78457 Konstanz, Germany
- Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
- Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
| | - Gillian Kiliani
- Department of Physics, University of Konstanz, 78457 Konstanz, Germany
| | - Matthias Kammerer
- Max Planck Institute for Intelligent Systems, 70569 Stuttgart, Germany
| | - Michael Curcic
- Max Planck Institute for Intelligent Systems, 70569 Stuttgart, Germany
| | - Markus Weigand
- Max Planck Institute for Intelligent Systems, 70569 Stuttgart, Germany
| | - Tolek Tyliszczak
- Advanced Light Source, LBL, University of California, Berkeley, Berkeley, California 94720, USA
| | | | - Hermann Stoll
- Max Planck Institute for Intelligent Systems, 70569 Stuttgart, Germany
| | - Gisela Schütz
- Max Planck Institute for Intelligent Systems, 70569 Stuttgart, Germany
| | - Kyung-Jin Lee
- Department of Materials Science and Engineering, Korea University, Seoul 136-713, Korea
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul 136-713, Korea
| | - Aurelien Manchon
- King Abdullah University of Science and Technology (KAUST), Physical Science and Engineering Division, Thuwal 23955-6900, Saudi Arabia
| | - Mathias Kläui
- Department of Physics, University of Konstanz, 78457 Konstanz, Germany
- Institute of Condensed Matter Physics, École Polytechnique Fédérale de Lausanne, 1015 Lausanne, Switzerland
- Paul Scherrer Institute, 5232 Villigen PSI, Switzerland
- Institut of Physics, Johannes Gutenberg University Mainz, 55099 Mainz, Germany
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20
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Cheng R, Zhu JG, Xiao D. Dynamic Feedback in Ferromagnet-Spin Hall Metal Heterostructures. PHYSICAL REVIEW LETTERS 2016; 117:097202. [PMID: 27610880 DOI: 10.1103/physrevlett.117.097202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/07/2016] [Indexed: 06/06/2023]
Abstract
In ferromagnet-normal-metal heterostructures, spin pumping and spin-transfer torques are two reciprocal processes that occur concomitantly. Their interplay introduces a dynamic feedback effect interconnecting energy dissipation channels of both magnetization and current. By solving the spin diffusion process in the presence of the spin Hall effect in the normal metal, we show that the dynamic feedback gives rise to (i) a nonlinear magnetic damping that is crucial to sustain uniform steady-state oscillations of a spin Hall oscillator at large angles and (ii) a frequency-dependent spin Hall magnetoimpedance that reduces to the spin Hall magnetoresistance in the dc limit.
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Affiliation(s)
- Ran Cheng
- Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
| | - Jian-Gang Zhu
- Department of Electrical and Computer Engineering, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
| | - Di Xiao
- Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213, USA
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21
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Koumpouras K, Bergman A, Eriksson O, Yudin D. A spin dynamics approach to solitonics. Sci Rep 2016; 6:25685. [PMID: 27156906 PMCID: PMC4860584 DOI: 10.1038/srep25685] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Accepted: 04/20/2016] [Indexed: 11/21/2022] Open
Abstract
In magnetic materials a variety of non-collinear ground state configurations may emerge as a result of competition among exchange, anisotropy, and dipole-dipole interaction, yielding magnetic states far more complex than those of homogenous ferromagnets. Of particular interest in this study are particle-like configurations. These particle-like states, e.g., magnetic solitons, skyrmions, or domain walls, form a spatially localised clot of magnetic energy. In this paper we address topologically protected magnetic solitons and explore concepts that potentially might be relevant for logical operations and/or information storage in the rapidly advancing filed of solitonics (and skyrmionics). An ability to easily create, address, and manipulate such structures is among the prerequisite forming a basis of "-onics technology", and is investigated in detail here using numerical and analytical tools.
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Affiliation(s)
- Konstantinos Koumpouras
- Department of Physics and Astronomy, Uppsala University, P.O. Box 516, 751 20 Uppsala, Sweden
| | - Anders Bergman
- Department of Physics and Astronomy, Uppsala University, P.O. Box 516, 751 20 Uppsala, Sweden
| | - Olle Eriksson
- Department of Physics and Astronomy, Uppsala University, P.O. Box 516, 751 20 Uppsala, Sweden
| | - Dmitry Yudin
- ITMO University, Saint Petersburg 197101, Russia
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22
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Kim KW, Lee KJ, Lee HW, Stiles MD. Intrinsic spin torque without spin-orbit coupling. PHYSICAL REVIEW. B, CONDENSED MATTER AND MATERIALS PHYSICS 2015; 92:224426. [PMID: 26877628 PMCID: PMC4748850 DOI: 10.1103/physrevb.92.224426] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
We derive an intrinsic contribution to the non-adiabatic spin torque for non-uniform magnetic textures. It differs from previously considered contributions in several ways and can be the dominant contribution in some models. It does not depend on the change in occupation of the electron states due to the current flow but rather is due to the perturbation of the electronic states when an electric field is applied. Therefore it should be viewed as electric-field-induced rather than current-induced. Unlike previously reported non-adiabatic spin torques, it does not originate from extrinsic relaxation mechanisms nor spin-orbit coupling. This intrinsic non-adiabatic spin torque is related by a chiral connection to the intrinsic spin-orbit torque that has been calculated from the Berry phase for Rashba systems.
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Affiliation(s)
- Kyoung-Whan Kim
- Basic Science Research Institute, Pohang University of Science and Technology, Pohang 790-784, Korea; PCTP and Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea; Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA; Maryland NanoCenter, University of Maryland, College Park, Maryland 20742, USA
| | - Kyung-Jin Lee
- Department of Materials Science and Engineering, Korea University, Seoul 136-701, 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, Pohang 790-784, Korea
| | - M D Stiles
- Center for Nanoscale Science and Technology, National Institute of Standards and Technology, Gaithersburg, Maryland 20899, USA
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23
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Du Z, Su R, Liu W, Huang Z. Magnetic nanoparticle thermometer: an investigation of minimum error transmission path and AC bias error. SENSORS 2015; 15:8624-41. [PMID: 25875188 PMCID: PMC4431289 DOI: 10.3390/s150408624] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/26/2015] [Revised: 04/02/2015] [Accepted: 04/03/2015] [Indexed: 11/23/2022]
Abstract
The signal transmission module of a magnetic nanoparticle thermometer (MNPT) was established in this study to analyze the error sources introduced during the signal flow in the hardware system. The underlying error sources that significantly affected the precision of the MNPT were determined through mathematical modeling and simulation. A transfer module path with the minimum error in the hardware system was then proposed through the analysis of the variations of the system error caused by the significant error sources when the signal flew through the signal transmission module. In addition, a system parameter, named the signal-to-AC bias ratio (i.e., the ratio between the signal and AC bias), was identified as a direct determinant of the precision of the measured temperature. The temperature error was below 0.1 K when the signal-to-AC bias ratio was higher than 80 dB, and other system errors were not considered. The temperature error was below 0.1 K in the experiments with a commercial magnetic fluid (Sample SOR-10, Ocean Nanotechnology, Springdale, AR, USA) when the hardware system of the MNPT was designed with the aforementioned method.
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Affiliation(s)
- Zhongzhou Du
- School of Automation, Huazhong University of Science and Technology, Wuhan 430074, China.
| | - Rijian Su
- School of Computer and Communication Engineering, Zhengzhou University of Light Industry, Zhengzhou 450002, China.
| | - Wenzhong Liu
- School of Automation, Huazhong University of Science and Technology, Wuhan 430074, China.
- Key Laboratory of Image Processing and Intelligent Control, Huazhong University of Science and Technology, Wuhan 430074, China.
| | - Zhixing Huang
- School of Automation, Huazhong University of Science and Technology, Wuhan 430074, China.
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24
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Spinmotive force due to motion of magnetic bubble arrays driven by magnetic field gradient. Sci Rep 2014; 4:6901. [PMID: 25365971 PMCID: PMC4219171 DOI: 10.1038/srep06901] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2014] [Accepted: 10/09/2014] [Indexed: 11/09/2022] Open
Abstract
Interaction between local magnetization and conduction electrons is responsible for a variety of phenomena in magnetic materials. It has been recently shown that spin current and associated electric voltage can be induced by magnetization that depends on both time and space. This effect, called spinmotive force, provides for a powerful tool for exploring the dynamics and the nature of magnetic textures, as well as a new source for electromotive force. Here we theoretically demonstrate the generation of electric voltages in magnetic bubble array systems subjected to a magnetic field gradient. It is shown by deriving expressions for the electric voltages that the present system offers a direct measure of phenomenological parameter β that describes non-adiabaticity in the current induced magnetization dynamics. This spinmotive force opens a door for new types of spintronic devices that exploit the field-gradient.
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25
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26
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Choi JY, Kang S, Seo SW, Kwon WJ, Shin YI. Observation of a geometric Hall effect in a spinor Bose-Einstein condensate with a Skyrmion spin texture. PHYSICAL REVIEW LETTERS 2013; 111:245301. [PMID: 24483673 DOI: 10.1103/physrevlett.111.245301] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/30/2013] [Indexed: 06/03/2023]
Abstract
For a spin-carrying particle moving in a spatially varying magnetic field, effective electromagnetic forces can arise due to the geometric phase associated with adiabatic spin rotation of the particle. We report the observation of a geometric Hall effect in a spinor Bose-Einstein condensate with a Skyrmion spin texture. Under translational oscillations of the spin texture, the condensate resonantly develops a circular motion in a harmonic trap, demonstrating the existence of an effective Lorentz force. When the condensate circulates, quantized vortices are nucleated in the boundary region of the condensate and the vortex number increases over 100 without significant heating. We attribute the vortex nucleation to the shearing effect of the effective Lorentz force from the inhomogeneous effective magnetic field.
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Affiliation(s)
- Jae-yoon Choi
- Center for Subwavelength Optics and Department of Physics and Astronomy, Seoul National University, Seoul 151-747, Korea
| | - Seji Kang
- Center for Subwavelength Optics and Department of Physics and Astronomy, Seoul National University, Seoul 151-747, Korea
| | - Sang Won Seo
- Center for Subwavelength Optics and Department of Physics and Astronomy, Seoul National University, Seoul 151-747, Korea
| | - Woo Jin Kwon
- Center for Subwavelength Optics and Department of Physics and Astronomy, Seoul National University, Seoul 151-747, Korea
| | - Yong-il Shin
- Center for Subwavelength Optics and Department of Physics and Astronomy, Seoul National University, Seoul 151-747, Korea
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27
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Kim KW, Lee HW, Lee KJ, Stiles MD. Chirality from interfacial spin-orbit coupling effects in magnetic bilayers. PHYSICAL REVIEW LETTERS 2013; 111:216601. [PMID: 24313509 DOI: 10.1103/physrevlett.111.216601] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Indexed: 06/02/2023]
Abstract
As nanomagnetic devices scale to smaller sizes, spin-orbit coupling due to the broken structural inversion symmetry at interfaces becomes increasingly important. Here, we study interfacial spin-orbit coupling effects in magnetic bilayers using a simple Rashba model. The spin-orbit coupling introduces chirality into the behavior of the electrons and through them into the energetics of the magnetization. In the derived form of the magnetization dynamics, all of the contributions that are linear in the spin-orbit coupling follow from this chirality, considerably simplifying the analysis. For these systems, an important consequence is a correlation between the Dzyaloshinskii-Moriya interaction and the spin-orbit torque. We use this correlation to analyze recent experiments.
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Affiliation(s)
- Kyoung-Whan Kim
- Basic Science Research Institute, Pohang University of Science and Technology, Pohang 790-784, Korea and Department of Physics, Pohang University of Science and Technology, Pohang 790-784, Korea
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28
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Armaitis J, Stoof HTC, Duine RA. Magnetization relaxation and geometric forces in a Bose ferromagnet. PHYSICAL REVIEW LETTERS 2013; 110:260404. [PMID: 23848850 DOI: 10.1103/physrevlett.110.260404] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/27/2013] [Indexed: 06/02/2023]
Abstract
We construct the hydrodynamic theory for spin-1/2 Bose gases at arbitrary temperatures. This theory describes the coupling between the magnetization and the normal and superfluid components of the gas. In particular, our theory contains the geometric forces on the particles that arise from their spin's adiabatic following of the magnetization texture. The phenomenological parameters of the hydrodynamic theory are calculated in the Bogoliubov approximation and using the Boltzmann equation in the relaxation-time approximation. We consider the topological Hall effect due to the presence of a Skyrmion, and show that this effect manifests itself in the collective modes of the system. The dissipative coupling between the magnetization and the normal component is shown to give rise to magnetization relaxation that is fourth order in spatial gradients of the magnetization direction.
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Affiliation(s)
- J Armaitis
- Institute for Theoretical Physics, Utrecht University, Leuvenlaan 4, 3584 CE Utrecht, The Netherlands.
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29
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Kim KW, Moon JH, Lee KJ, Lee HW. Prediction of giant spin motive force due to Rashba spin-orbit coupling. PHYSICAL REVIEW LETTERS 2012; 108:217202. [PMID: 23003294 DOI: 10.1103/physrevlett.108.217202] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2011] [Revised: 02/02/2012] [Indexed: 06/01/2023]
Abstract
Magnetization dynamics in a ferromagnet can induce a spin-dependent electric field through a spin motive force. Spin current generated by the spin-dependent electric field can in turn modify the magnetization dynamics through spin-transfer torque. While this feedback effect is usually weak and thus ignored, we predict that in Rashba spin-orbit coupling systems with a large Rashba parameter α(R), the coupling generates the spin-dependent electric field [±(α(R)m(e)/eħ)(z[over ^]×∂m/∂t)], which can be large enough to modify the magnetization dynamics significantly. This effect should be relevant for device applications based on ultrathin magnetic layers with strong Rashba spin-orbit coupling.
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Affiliation(s)
- Kyoung-Whan Kim
- PCTP and Department of Physics, Pohang University of Science and Technology, Pohang, Korea
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30
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Spin-motive force due to a gyrating magnetic vortex. Nat Commun 2012; 3:845. [DOI: 10.1038/ncomms1824] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2011] [Accepted: 04/05/2012] [Indexed: 11/08/2022] Open
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31
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Brataas A, Kent AD, Ohno H. Current-induced torques in magnetic materials. NATURE MATERIALS 2012; 11:372-381. [PMID: 22522637 DOI: 10.1038/nmat3311] [Citation(s) in RCA: 226] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
The magnetization of a magnetic material can be reversed by using electric currents that transport spin angular momentum. In the reciprocal process a changing magnetization orientation produces currents that transport spin angular momentum. Understanding how these processes occur reveals the intricate connection between magnetization and spin transport, and can transform technologies that generate, store or process information via the magnetization direction. Here we explain how currents can generate torques that affect the magnetic orientation and the reciprocal effect in a wide variety of magnetic materials and structures. We also discuss recent state-of-the-art demonstrations of current-induced torque devices that show great promise for enhancing the functionality of semiconductor devices.
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Affiliation(s)
- Arne Brataas
- Department of Physics, Norwegian University of Science and Technology, NO-7191 Trondheim, Norway.
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32
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Hayashi M, Ieda J, Yamane Y, Ohe JI, Takahashi YK, Mitani S, Maekawa S. Time-domain observation of the spinmotive force in permalloy nanowires. PHYSICAL REVIEW LETTERS 2012; 108:147202. [PMID: 22540820 DOI: 10.1103/physrevlett.108.147202] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2011] [Indexed: 05/31/2023]
Abstract
The spinmotive force associated with a moving domain wall is observed directly in Permalloy nanowires using real time voltage measurements with proper subtraction of the electromotive force. Whereas the wall velocity exhibits nonlinear dependence on magnetic field, the generated voltage increases linearly with the field. We show that the sign of the voltage reverses when the wall propagation direction is altered. Numerical simulations explain quantitatively these features of spinmotive force and indicate that it scales with the field even in a field range where the wall motion is no longer associated with periodic angular rotation of the wall magnetization.
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33
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Yamane Y, Sasage K, An T, Harii K, Ohe J, Ieda J, Barnes SE, Saitoh E, Maekawa S. Continuous generation of spinmotive force in a patterned ferromagnetic film. PHYSICAL REVIEW LETTERS 2011; 107:236602. [PMID: 22182112 DOI: 10.1103/physrevlett.107.236602] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/29/2011] [Indexed: 05/31/2023]
Abstract
We study, both experimentally and theoretically, the generation of a dc spinmotive force. By exciting a ferromagnetic resonance of a comb-shaped ferromagnetic thin film, a continuous spinmotive force is generated. Experimental results are well reproduced by theoretical calculations, offering a quantitative and microscopic understanding of this spinmotive force.
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Affiliation(s)
- Y Yamane
- Advanced Science Research Center, Japan Atomic Energy Agency, Tokai 319-1195, Japan.
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34
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Dempsey KJ, Ciudad D, Marrows CH. Single electron spintronics. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2011; 369:3150-3174. [PMID: 21727119 DOI: 10.1098/rsta.2011.0105] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Single electron electronics is now well developed, and allows the manipulation of electrons one-by-one as they tunnel on and off a nanoscale conducting island. In the past decade or so, there have been concerted efforts in several laboratories to construct single electron devices incorporating ferromagnetic components in order to introduce spin functionality. The use of ferromagnetic electrodes with a non-magnetic island can lead to spin accumulation on the island. On the other hand, making the dot also ferromagnetic introduces new physics such as tunnelling magnetoresistance enhancement in the cotunnelling regime and manifestations of the Kondo effect. Such nanoscale islands are also found to have long spin lifetimes. Conventional spintronics makes use of the average spin-polarization of a large ensemble of electrons: this new approach offers the prospect of accessing the quantum properties of the electron, and is a candidate approach to the construction of solid-state spin-based qubits.
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Affiliation(s)
- Kari J Dempsey
- School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK
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35
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Matsuo M, Ieda J, Saitoh E, Maekawa S. Effects of mechanical rotation on spin currents. PHYSICAL REVIEW LETTERS 2011; 106:076601. [PMID: 21405528 DOI: 10.1103/physrevlett.106.076601] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/01/2010] [Indexed: 05/30/2023]
Abstract
We study the Pauli-Schrödinger equation in a uniformly rotating frame of reference to describe a coupling of spins and mechanical rotations. The explicit form of the spin-orbit interaction (SOI) with the inertial effects due to the mechanical rotation is presented. We derive equations of motion for a wave packet of electrons in two-dimensional planes subject to the SOI. The solution is a superposition of two cyclotron motions with different frequencies and a circular spin current is created by the mechanical rotation. The magnitude of the spin current is linearly proportional to the lower cyclotron frequency.
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Affiliation(s)
- Mamoru Matsuo
- Yukawa Institute for Theoretical Physics, Kyoto University, Japan
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36
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Mostovoy M, Nomura K, Nagaosa N. Theory of electric polarization in multiorbital Mott insulators. PHYSICAL REVIEW LETTERS 2011; 106:047204. [PMID: 21405357 DOI: 10.1103/physrevlett.106.047204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/18/2010] [Indexed: 05/30/2023]
Abstract
The interaction between the electric field E and spins in multiorbital Mott insulators is studied theoretically. We find a generic coupling mechanism, which works for all crystal lattices and which does not involve relativistic effects. It couples E to the "internal" electric field e originating from the dynamical Berry phase. We discuss several effects of this interaction: (i) an unusual electron spin resonance, (ii) the displacement of spin textures in an applied electric field, and (iii) the resonant absorption of circularly polarized light by Skyrmions, magnetic bubbles, and magnetic vortices.
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Affiliation(s)
- Maxim Mostovoy
- Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, Groningen 9747 AG, The Netherlands
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37
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Hals KMD, Nguyen AK, Brataas A. Intrinsic coupling between current and domain wall motion in (Ga,Mn)As. PHYSICAL REVIEW LETTERS 2009; 102:256601. [PMID: 19659106 DOI: 10.1103/physrevlett.102.256601] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/10/2008] [Indexed: 05/28/2023]
Abstract
We consider current-induced domain wall motion and, the reciprocal process, moving domain wall-induced current. The associated Onsager coefficients are expressed in terms of scattering matrices. Uncommonly, in (Ga,Mn)As, the effective Gilbert damping coefficient alphaw and the effective out-of-plane spin-transfer torque parameter betaw are dominated by spin-orbit interaction in combination with scattering off the domain wall, and not scattering off extrinsic impurities. Numerical calculations give alphaw approximately 0.01 and betaw approximately 1 in dirty (Ga,Mn)As. The extraordinarily large betaw parameter allows experimental detection of current or voltage induced by domain wall motion in (Ga,Mn)As.
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Hai PN, Ohya S, Tanaka M, Barnes SE, Maekawa S. Electromotive force and huge magnetoresistance in magnetic tunnel junctions. Nature 2009; 458:489-92. [DOI: 10.1038/nature07879] [Citation(s) in RCA: 146] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2008] [Accepted: 02/12/2009] [Indexed: 11/09/2022]
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Zhang S, Zhang SSL. Generalization of the Landau-Lifshitz-Gilbert equation for conducting ferromagnets. PHYSICAL REVIEW LETTERS 2009; 102:086601. [PMID: 19257763 DOI: 10.1103/physrevlett.102.086601] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2008] [Indexed: 05/27/2023]
Abstract
We propose an extension of the Landau-Lifshitz-Gilbert (LLG) equation by explicitly including the role of conduction electrons in magnetization dynamics of conducting ferromagnets. The temporal and spatial dependent magnetization order parameter m(r,t) generates both electrical and spin currents that provide dissipation of the energy and angular momentum of the processing magnet. The resulting LLG equation contains highly spatial dependence of damping term and thus micromagnetic simulations based on the standard LLG equation should be reexamined for magnetization dynamics involving narrow domain walls and spin waves with short wavelengths.
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Affiliation(s)
- Shufeng Zhang
- Department of Physics, University of Arizona, Tucson, Arizona 85721, USA
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Shibata J, Kohno H. Inverse spin Hall effect driven by spin motive force. PHYSICAL REVIEW LETTERS 2009; 102:086603. [PMID: 19257765 DOI: 10.1103/physrevlett.102.086603] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/03/2008] [Indexed: 05/27/2023]
Abstract
The spin Hall effect is a phenomenon in which an electric field induces a spin Hall current. In this Letter, we examine the inverse effect that, in a ferromagnetic conductor, a charge Hall current is induced by a spin motive force, or a spin-dependent effective "electric" field E_{s}, arising from the time variation of magnetization texture. By considering skew-scattering and side-jump processes due to spin-orbit interaction at impurities, we obtain the Hall current density as sigma_{SH}n x E_{s}, where n is the local spin direction and sigma_{SH} is the spin Hall conductivity. The Hall angle due to the spin motive force is enhanced by a factor of P-2 compared to the conventional anomalous Hall effect due to the ordinary electric field, where P is the spin polarization of the current. The Hall voltage is estimated for a field-driven domain-wall oscillation in a ferromagnetic nanowire.
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Affiliation(s)
- Junya Shibata
- Kanagawa Institute of Technology, 1030 Shimo-Ogino Atsugi, Kanagawa 243-0292, Japan.
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Yang SA, Beach GSD, Knutson C, Xiao D, Niu Q, Tsoi M, Erskine JL. Universal electromotive force induced by domain wall motion. PHYSICAL REVIEW LETTERS 2009; 102:067201. [PMID: 19257626 DOI: 10.1103/physrevlett.102.067201] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2008] [Indexed: 05/27/2023]
Abstract
The electromotive force induced by a moving magnetic domain wall in a nanostrip has been calculated theoretically and detected experimentally. It is found that the emf depends only on the domain wall transformation frequency through a universal Josephson type relation, which is closely related to the topological nature of the domain wall. Our experimental measurements confirm the theoretical prediction.
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Affiliation(s)
- Shengyuan A Yang
- Department of Physics, The University of Texas, Austin, Texas, 78712-0264, USA
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Ohe JI, Takeuchi A, Tatara G. Charge current driven by spin dynamics in disordered Rashba spin-orbit system. PHYSICAL REVIEW LETTERS 2007; 99:266603. [PMID: 18233596 DOI: 10.1103/physrevlett.99.266603] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2007] [Indexed: 05/25/2023]
Abstract
Pumping of charge current by spin dynamics in the presence of the Rashba spin-orbit interaction is theoretically studied. Considering a disordered electron, the exchange coupling and spin-orbit interactions are treated perturbatively. It is found that the dominant current induced by spin dynamics is interpreted as a consequence of the conversion from spin current via the inverse spin Hall effect. We also find that the current has an additional component from a fictitious conservative field. The results are applied to the case of a moving domain wall.
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Affiliation(s)
- Jun-Ichiro Ohe
- I. Institut für Theoretische Physik, Universtität Hamburg, Jungiusstrasse 9, 20355 Hamburg, Germany
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