1
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Taniguchi T, Imai Y. Spintronic virtual neural network by a voltage controlled ferromagnet for associative memory. Sci Rep 2024; 14:8188. [PMID: 38589599 PMCID: PMC11002033 DOI: 10.1038/s41598-024-58556-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2024] [Accepted: 04/01/2024] [Indexed: 04/10/2024] Open
Abstract
Recently, an associative memory operation by a virtual oscillator network, consisting of a single spintronic oscillator, was examined to solve issues in conventional, real oscillators-based neural networks such as inhomogeneities between the oscillators. However, the spintronic oscillator still carries issues dissipating large amount of energy because it is driven by electric current. Here, we propose to use a single ferromagnet manipulated by voltage-controlled magnetic anisotropy (VCMA) effect as a fundamental element in a virtual neural network, which will contribute to significantly reducing the Joule heating caused by electric current. Instead of the oscillation in oscillator networks, magnetization relaxation dynamics were used for the associative memory operation. The associative memory operation for alphabet patterns is successfully demonstrated by giving correspondences between the colors in a pattern recognition task and the sign of a perpendicular magnetic anisotropy coefficient, which could be either positive or negative via the VCMA effect.
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Affiliation(s)
- Tomohiro Taniguchi
- National Institute of Advanced Industrial Science and Technology (AIST), Research Center for Emerging Computing Technologies, Tsukuba, Ibaraki, 305-8568, Japan.
| | - Yusuke Imai
- Graduate School of Information Science and Technology, The University of Tokyo, Bunkyo-ku, Tokyo, 113-8656, Japan
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2
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Taniguchi T. Bifurcation to complex dynamics in largely modulated voltage-controlled parametric oscillator. Sci Rep 2024; 14:2891. [PMID: 38316855 PMCID: PMC10844235 DOI: 10.1038/s41598-024-53503-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Accepted: 02/01/2024] [Indexed: 02/07/2024] Open
Abstract
An experimental demonstration of a parametric oscillation of a magnetization in a ferromagnet was performed recently by applying a microwave voltage, indicating the potential to be applied in a switching method in non-volatile memories. In the previous works, the modulation of a perpendicular magnetic anisotropy field produced by the microwave voltage was small compared with an external magnetic field pointing in an in-plane direction. A recent trend is, however, opposite, where an efficiency of the voltage controlled magnetic anisotropy (VCMA) effect is increased significantly by material research and thus, the modulated magnetic anisotropy field can be larger than the external magnetic field. Here, we solved the Landau-Lifshitz-Gilbert equation numerically and investigated the magnetization dynamics driven under a wide range of the microwave VCMA effect. We evaluated bifurcation diagrams, which summarize local maxima of the magnetization dynamics. For low modulation amplitudes, the local maximum is a single point because the dynamics is the periodic parametric oscillation. The bifurcation diagrams show distributions of the local maxima when the microwave magnetic anisotropy field becomes larger than the external magnetic field. The appearance of this broadened distribution indicates complex dynamics such as chaotic and transient-chaotic behaviors, which were confirmed from an analysis of temporal dynamics.
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Affiliation(s)
- Tomohiro Taniguchi
- National Institute of Advanced Industrial Science and Technology (AIST), Research Center for Emerging Computing Technologies, Tsukuba, Ibaraki, 305-8568, Japan.
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3
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Xiao Y, Zou G, Huo J, Sun T, Peng J, Li Z, Shen D, Liu L. Local modulation of Au/MoS 2 Schottky barriers using a top ZnO nanowire gate for high-performance photodetection. NANOSCALE HORIZONS 2024; 9:285-294. [PMID: 38063807 DOI: 10.1039/d3nh00448a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2024]
Abstract
Schottky junctions are commonly used for fabricating heterojunction-based 2D transition metal dichalcogenide (TMD) photodetectors, characteristically offering a wide detection range, high sensitivity and fast response. However, these devices often suffer from reduced detectivity due to the high dark current, making it challenging to discover a simple and efficient universal way to improve the photoelectric performances. Here, we demonstrate a novel approach for integrating ZnO nanowire gates into a MoS2-Au Schottky junction to improve the photoelectric performances of photodetectors by locally controlling the Schottky barrier. This strategy remarkably reduces the dark current level of the device without affecting its photocurrent and the Schottky detectivity can be modified to a maximum detectivity of 1.4 × 1013 Jones with -20 V NG bias. This work provides potential possibilities for tuning the band structure of other materials and optimizing the performance of heterojunction photodetectors.
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Affiliation(s)
- Yu Xiao
- Department of Mechanical Engineering, State Key Laboratory of Tribology, Key Laboratory for Advanced Manufacturing by Materials Processing Technology, Ministry of Education of PR China, Tsinghua University, Beijing 100084, P. R. China.
| | - Guisheng Zou
- Department of Mechanical Engineering, State Key Laboratory of Tribology, Key Laboratory for Advanced Manufacturing by Materials Processing Technology, Ministry of Education of PR China, Tsinghua University, Beijing 100084, P. R. China.
| | - Jinpeng Huo
- Department of Mechanical Engineering, State Key Laboratory of Tribology, Key Laboratory for Advanced Manufacturing by Materials Processing Technology, Ministry of Education of PR China, Tsinghua University, Beijing 100084, P. R. China.
| | - Tianming Sun
- Department of Mechanical Engineering, State Key Laboratory of Tribology, Key Laboratory for Advanced Manufacturing by Materials Processing Technology, Ministry of Education of PR China, Tsinghua University, Beijing 100084, P. R. China.
- College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan 030024, Shanxi Province, China
| | - Jin Peng
- Department of Mechanical Engineering, State Key Laboratory of Tribology, Key Laboratory for Advanced Manufacturing by Materials Processing Technology, Ministry of Education of PR China, Tsinghua University, Beijing 100084, P. R. China.
| | - Zehua Li
- Department of Mechanical Engineering, State Key Laboratory of Tribology, Key Laboratory for Advanced Manufacturing by Materials Processing Technology, Ministry of Education of PR China, Tsinghua University, Beijing 100084, P. R. China.
| | - Daozhi Shen
- School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Lei Liu
- Department of Mechanical Engineering, State Key Laboratory of Tribology, Key Laboratory for Advanced Manufacturing by Materials Processing Technology, Ministry of Education of PR China, Tsinghua University, Beijing 100084, P. R. China.
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4
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Ilse SE, Schütz G, Goering E. Voltage X-Ray Reflectometry: A Method to Study Electric-Field-Induced Changes in Interfacial Electronic Structures. PHYSICAL REVIEW LETTERS 2023; 131:036201. [PMID: 37540862 DOI: 10.1103/physrevlett.131.036201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2023] [Revised: 04/26/2023] [Accepted: 06/07/2023] [Indexed: 08/06/2023]
Abstract
Magnetic multilayers with a separating insulating layer are used in a multitude of functional devices. Controlling the magnetic properties of such devices with an electric field has the potential to vastly enhance their performance. Nevertheless, experimental methods to study the origin of electric-field-induced effects on buried interfaces remain elusive. By using element selective x-ray resonant magnetic reflectometry we are able to gain access to changes in the electronic structure of interfacial atoms caused by an electric field. With this method it is possible to probe interfacial states at the Fermi energy. In a multilayer stack with a Ni/SiO_{2} interface, we find that the electric field slightly shifts the Ni L_{3}-edge in energy, which indicates a change of the oxidation state of interfacial Ni atoms. Further analysis of the strength of the effect reveals that only about 30% of the electrons moved by the electric field end up in interfacial Ni states.
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Affiliation(s)
- Sven Erik Ilse
- Max-Planck-Institute for Solid State Research, D-70569 Stuttgart, Germany
| | - Gisela Schütz
- Max-Planck-Institute for Intelligent Systems, D-70569 Stuttgart, Germany
| | - Eberhard Goering
- Max-Planck-Institute for Solid State Research, D-70569 Stuttgart, Germany
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5
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Dai B, Wu D, Razavi SA, Xu S, He H, Shu Q, Jackson M, Mahfouzi F, Huang H, Pan Q, Cheng Y, Qu T, Wang T, Tai L, Wong K, Kioussis N, Wang KL. Electric field manipulation of spin chirality and skyrmion dynamic. SCIENCE ADVANCES 2023; 9:eade6836. [PMID: 36791189 PMCID: PMC9931210 DOI: 10.1126/sciadv.ade6836] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Accepted: 01/12/2023] [Indexed: 06/18/2023]
Abstract
The Dzyaloshinskii-Moriya interaction (DMI) is an antisymmetric exchange interaction that stabilizes spin chirality. One scientific and technological challenge is understanding and controlling the interaction between spin chirality and electric field. In this study, we investigate an unconventional electric field effect on interfacial DMI, skyrmion helicity, and skyrmion dynamics in a system with broken inversion symmetry. We design heterostructures with a 3d-5d atomic orbital interface to demonstrate the gate bias control of the DMI energy and thus transform the DMI between opposite chiralities. Furthermore, we use this voltage-controlled DMI (VCDMI) to manipulate the skyrmion spin texture. As a result, a type of intermediate skyrmion with a unique helicity is created, and its motion can be controlled and made to go straight. Our work shows the effective control of spin chirality, skyrmion helicity, and skyrmion dynamics by VCDMI. It promotes the emerging field of voltage-controlled chiral interactions and voltage-controlled skyrmionics.
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Affiliation(s)
- Bingqian Dai
- Departments of Electrical and Computer Engineering, Physics and Astronomy, and Material Science and Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Di Wu
- Departments of Electrical and Computer Engineering, Physics and Astronomy, and Material Science and Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Seyed Armin Razavi
- Departments of Electrical and Computer Engineering, Physics and Astronomy, and Material Science and Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Shijie Xu
- Departments of Electrical and Computer Engineering, Physics and Astronomy, and Material Science and Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Haoran He
- Departments of Electrical and Computer Engineering, Physics and Astronomy, and Material Science and Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Qingyuan Shu
- Departments of Electrical and Computer Engineering, Physics and Astronomy, and Material Science and Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Malcolm Jackson
- Departments of Electrical and Computer Engineering, Physics and Astronomy, and Material Science and Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Farzad Mahfouzi
- Department of Physics and Astronomy, California State University, Northridge, Los Angeles, CA 91330-8268, USA
| | - Hanshen Huang
- Departments of Electrical and Computer Engineering, Physics and Astronomy, and Material Science and Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Quanjun Pan
- Departments of Electrical and Computer Engineering, Physics and Astronomy, and Material Science and Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Yang Cheng
- Departments of Electrical and Computer Engineering, Physics and Astronomy, and Material Science and Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Tao Qu
- Departments of Electrical and Computer Engineering, Physics and Astronomy, and Material Science and Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Tianyi Wang
- Departments of Electrical and Computer Engineering, Physics and Astronomy, and Material Science and Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Lixuan Tai
- Departments of Electrical and Computer Engineering, Physics and Astronomy, and Material Science and Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Kin Wong
- Departments of Electrical and Computer Engineering, Physics and Astronomy, and Material Science and Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA
| | - Nicholas Kioussis
- Department of Physics and Astronomy, California State University, Northridge, Los Angeles, CA 91330-8268, USA
| | - Kang L. Wang
- Departments of Electrical and Computer Engineering, Physics and Astronomy, and Material Science and Engineering, University of California, Los Angeles, Los Angeles, CA 90095, USA
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6
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Wang ZA, Xue W, Yan F, Zhu W, Liu Y, Zhang X, Wei Z, Chang K, Yuan Z, Wang K. Selectively Controlled Ferromagnets by Electric Fields in van der Waals Ferromagnetic Heterojunctions. NANO LETTERS 2023; 23:710-717. [PMID: 36626837 DOI: 10.1021/acs.nanolett.2c04796] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/17/2023]
Abstract
Charge transfer plays a key role at the interfaces of heterostructures, which can affect electronic structures and ultimately the physical properties of the materials. However, charge transfer is difficult to manipulate externally once the interface is formed. The recently discovered van der Waals ferromagnets with atomically sharp interfaces provided a perfect platform for the electrical control of interfacial charge transfer. Here, we report magnetoresistance experiments revealing electrically tunable charge transfer in Fe3GeTe2/Cr2Ge2Te6/Fe3GeTe2 all-magnetic van der Waals heterostructures, which can be exploited to selectively modify the switching fields of the top or bottom Fe3GeTe2 electrodes. The directional charge transfer from metallic Fe3GeTe2 to semiconducting Cr2Ge2Te6 is revealed by first-principles calculations, which remarkably modifies the magnetic anisotropy energy of Fe3GeTe2, leading to the dramatically suppressed coercivity. The electrically selective control of magnetism demonstrated in this study could stimulate the development of spintronic devices based on van der Waals magnets.
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Affiliation(s)
- Zi-Ao Wang
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Weishan Xue
- Center for Advanced Quantum Studies and Department of Physics, Beijing Normal University, Beijing 100875, China
| | - Faguang Yan
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
| | - Wenkai Zhu
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
| | - Yi Liu
- Center for Advanced Quantum Studies and Department of Physics, Beijing Normal University, Beijing 100875, China
| | - Xinhui Zhang
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhongming Wei
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Kai Chang
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
| | - Zhe Yuan
- Center for Advanced Quantum Studies and Department of Physics, Beijing Normal University, Beijing 100875, China
| | - Kaiyou Wang
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, Beijing 100083, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing 100049, China
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7
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Miura Y, Okabayashi J. Understanding magnetocrystalline anisotropy based on orbital and quadrupole moments. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2022; 34:473001. [PMID: 36137512 DOI: 10.1088/1361-648x/ac943f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Accepted: 09/22/2022] [Indexed: 06/16/2023]
Abstract
Understanding magnetocrystalline anisotropy (MCA) is fundamentally important for developing novel magnetic materials. Therefore, clarifying the relationship between MCA and local physical quantities observed by spectroscopic measurements, such as the orbital and quadrupole moments, is necessary. In this review, we discuss MCA and the distortion effects in magnetic materials with transition metals (TMs) based on the orbital and quadrupole moments, which are related to the spin-conserving and spin-flip terms in the second-order perturbation calculations, respectively. We revealed that orbital moment stabilized the spin moment in the direction of the larger orbital moment, while the quadrupole moment stabilized the spin moment along the longitudinal direction of the spin-density distribution. The MCA of the magnetic materials with TMs and their interfaces can be determined from the competition between these two contributions. We showed that the perpendicular MCA of the face-centered cubic Ni with tensile tetragonal distortion arose from the orbital moment anisotropy, whereas that of Mn-Ga alloys originated from the quadrupole moment of spin density. In contrast, in the Co/Pd(111) multilayer and Fe/MgO(001), both the orbital moment anisotropy and quadrupole moment of spin density at the interfaces contributed to the perpendicular MCA. Understanding the MCA of magnetic materials and interfaces based on orbital and quadrupole moments is essential to design MCA of novel magnetic applications.
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Affiliation(s)
- Yoshio Miura
- Research Center for Magnetic and Spintronic Materials, National Institute for Materials Science (NIMS), Sengen 1-2-1, Tsukuba 305-0047, Japan
- Center for Spintronics Research Network (CSRN), Graduate School of Engineering Science, Osaka University, Machikaneyama 1-3, Toyonaka, Osaka 560-8531, Japan
| | - Jun Okabayashi
- Research Center for Spectrochemistry, The University of Tokyo, Bunkyo-ku, Tokyo 113-0033, Japan
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8
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Spintronic reservoir computing without driving current or magnetic field. Sci Rep 2022; 12:10627. [PMID: 35739232 PMCID: PMC9226059 DOI: 10.1038/s41598-022-14738-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2022] [Accepted: 06/13/2022] [Indexed: 11/18/2022] Open
Abstract
Recent studies have shown that nonlinear magnetization dynamics excited in nanostructured ferromagnets are applicable to brain-inspired computing such as physical reservoir computing. The previous works have utilized the magnetization dynamics driven by electric current and/or magnetic field. This work proposes a method to apply the magnetization dynamics driven by voltage control of magnetic anisotropy to physical reservoir computing, which will be preferable from the viewpoint of low-power consumption. The computational capabilities of benchmark tasks in single MTJ are evaluated by numerical simulation of the magnetization dynamics and found to be comparable to those of echo-state networks with more than 10 nodes.
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9
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Large voltage-induced coercivity change in Pt/Co/CoO/amorphous TiO x structure and heavy metal insertion effect. Sci Rep 2021; 11:21448. [PMID: 34728733 PMCID: PMC8564507 DOI: 10.1038/s41598-021-00960-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2021] [Accepted: 10/20/2021] [Indexed: 11/08/2022] Open
Abstract
There is urgent need for spintronics materials exhibiting a large voltage modulation effect to fulfill the great demand for high-speed, low-power-consumption information processing systems. Fcc-Co (111)-based systems are a promising option for research on the voltage effect, on account of their large perpendicular magnetic anisotropy (PMA) and high degree of freedom in structure. Aiming to observe a large voltage effect in a fcc-Co (111)-based system at room temperature, we investigated the voltage-induced coercivity (Hc) change of perpendicularly magnetized Pt/heavy metal/Co/CoO/amorphous TiOx structures. The thin CoO layer in the structure was the result of the surface oxidation of Co. We observed a large voltage-induced Hc change of 20.2 mT by applying 2 V (0.32 V/nm) to a sample without heavy metal insertion, and an Hc change of 15.4 mT by applying 1.8 V (0.29 V/nm) to an Ir-inserted sample. The relative thick Co thickness, Co surface oxidation, and large dielectric constant of TiOx layer could be related to the large voltage-induced Hc change. Furthermore, we demonstrated the separate adjustment of Hc and a voltage-induced Hc change by utilizing both upper and lower interfaces of Co.
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10
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Cheng M, Zhang Z, Yuan X, Liu Y, Lu Z, Xiong R, Shi J. The large perpendicular magnetic anisotropy induced at the Co 2FeAl/MgAl 2O 4interface and tuned with the strain, voltage and charge doping by first principles study. NANOTECHNOLOGY 2021; 32:495702. [PMID: 34438388 DOI: 10.1088/1361-6528/ac218f] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Accepted: 08/25/2021] [Indexed: 06/13/2023]
Abstract
The heterostructures with high perpendicular magnetic anisotropy (PMA) have advantages for the application of the nonvolatile memories with long data retention time and small size. The interface structure and magnetic anisotropy energy (MAE) of Co2FeAl/MgAl2O4heterostructures were studied by first principles calculations. The stable interface atomic arrangement is the Co or FeAl layer located above the equatorial oxygen coordinate in the distorted oxygen octahedrons. The Co-O interface can induce large effective PMA up to 4.54 mJ m-2, but this structure is a metastable structure. Meanwhile, the effective MAE decreases linearly as the thickness of the ferromagnetic layer increase. The effective MAE for the FeAl-O interface is only 1.3 mJ m-2, while the maximum thickness of Co2FeAl layer that maintains the PMA effect is about 1.717 nm. These values are very close to the experimental results. Throughd-orbital-resolved MAE, we confirm that the interface PMA is mainly originated from the hybridization betweendxy,dyzanddz2orbitals of interface 3datoms. In addition, the compressive strain, negative electric field and hole doping can significantly enhance the effective PMA of FeAl-O interface. At the same time, Co-O interface will become the most stable structure by tuning the Mg/Al ratio in the spinel layers. The large effective PMA makes the Co2FeAl/MgAl2O4junction a perfect candidate for the next-generation of non-volatile spintronic devices.
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Affiliation(s)
- Ming Cheng
- Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072, People's Republic of China
| | - Zhenhua Zhang
- Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072, People's Republic of China
| | - Xiaojuan Yuan
- The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081, People's Republic of China
- School of Materials and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081, People's Republic of China
| | - Yong Liu
- Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072, People's Republic of China
| | - Zhihong Lu
- The State Key Laboratory of Refractories and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081, People's Republic of China
- School of Materials and Metallurgy, Wuhan University of Science and Technology, Wuhan 430081, People's Republic of China
| | - Rui Xiong
- Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072, People's Republic of China
| | - Jing Shi
- Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, School of Physics and Technology, Wuhan University, Wuhan 430072, People's Republic of China
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11
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One RA, Béa H, Mican S, Joldos M, Veiga PB, Dieny B, Buda-Prejbeanu LD, Tiusan C. Route towards efficient magnetization reversal driven by voltage control of magnetic anisotropy. Sci Rep 2021; 11:8801. [PMID: 33888853 PMCID: PMC8062633 DOI: 10.1038/s41598-021-88408-z] [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: 01/29/2021] [Accepted: 04/12/2021] [Indexed: 11/09/2022] Open
Abstract
The voltage controlled magnetic anisotropy (VCMA) becomes a subject of major interest for spintronics due to its promising potential outcome: fast magnetization manipulation in magnetoresistive random access memories with enhanced storage density and very low power consumption. Using a macrospin approach, we carried out a thorough analysis of the role of the VCMA on the magnetization dynamics of nanostructures with out-of-plane magnetic anisotropy. Diagrams of the magnetization switching have been computed depending on the material and experiment parameters (surface anisotropy, Gilbert damping, duration/amplitude of electric and magnetic field pulses) thus allowing predictive sets of parameters for optimum switching experiments. Two characteristic times of the trajectory of the magnetization were analyzed analytically and numerically setting a lower limit for the duration of the pulses. An interesting switching regime has been identified where the precessional reversal of magnetization does not depend on the voltage pulse duration. This represents a promising path for the magnetization control by VCMA with enhanced versatility.
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Affiliation(s)
- Roxana-Alina One
- Faculty of Physics, Babes-Bolyai University, Cluj-Napoca, Cluj, Romania.,Univ. Grenoble Alpes, CEA, CNRS, G-INP, IRIG-SPINTEC, Grenoble, France
| | - Hélène Béa
- Univ. Grenoble Alpes, CEA, CNRS, G-INP, IRIG-SPINTEC, Grenoble, France
| | - Sever Mican
- Faculty of Physics, Babes-Bolyai University, Cluj-Napoca, Cluj, Romania
| | - Marius Joldos
- Technical University of Cluj-Napoca, Cluj-Napoca, Romania
| | | | - Bernard Dieny
- Univ. Grenoble Alpes, CEA, CNRS, G-INP, IRIG-SPINTEC, Grenoble, France
| | | | - Coriolan Tiusan
- Faculty of Physics, Babes-Bolyai University, Cluj-Napoca, Cluj, Romania. .,Technical University of Cluj-Napoca, Cluj-Napoca, Romania.
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12
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Streubel R, N'Diaye AT, Srinivasan K, Kalitsov A, Jain S, Ajan A, Fischer P. The effect of Cu additions in FePt-BN-SiO 2 heat-assisted magnetic recording media. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:104003. [PMID: 33264766 DOI: 10.1088/1361-648x/abcff8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Structural and chemical order impact magnetic properties of solids, which are governed by spin-orbit coupling and exchange interaction. The ordered L10 phase of FePt is a key material to heat-assisted magnetic recording; to enable high storage density, a solid understanding is needed of structural and chemical disorder at small length scales, as well as associated modifications of the electronic band structure. Here, we investigate the effect of boron and copper additions (≲6 mol% Cu) on structural and magnetic properties of L10 FePt granular media. Two copper-driven mechanisms, although competing, can lead to improvements in both structural and magnetic properties. In particular, the Cu substitution on the Fe-site leads to a degradation of magnetic properties due to the delocalized electron orbitals originating from a larger Cu d-orbital occupancy. At the same time, Cu substitution leads to an enhanced crystallographic order and consequently magneto-crystalline anisotropy, which offsets the former effect to a large extent. Our study is based on magnetometry, x-ray absorption spectroscopy, ab-initio calculations and a phenomenological theory of disordered FePt granular media. We do not observe a sizable modification to Fe moments and electronic configuration; Cu reveals two different resonances associated with the presence and absence of Cu-B bonds that vary with total Cu concentration.
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Affiliation(s)
- Robert Streubel
- Department of Physics and Astronomy, University of Nebraska-Lincoln, Lincoln, NE 68588, United States of America
- Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, NE 68588, United States of America
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley CA 94720, United States of America
| | - Alpha T N'Diaye
- Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley CA 94720, United States of America
| | - Kumar Srinivasan
- Western Digital, 5601 Great Oaks Parkway, San Jose, CA 95119, United States of America
| | - Alan Kalitsov
- Western Digital, 5601 Great Oaks Parkway, San Jose, CA 95119, United States of America
| | - Shikha Jain
- Western Digital, 5601 Great Oaks Parkway, San Jose, CA 95119, United States of America
| | - Antony Ajan
- Western Digital, 5601 Great Oaks Parkway, San Jose, CA 95119, United States of America
| | - Peter Fischer
- Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley CA 94720, United States of America
- Physics Department, UC Santa Cruz, Santa Cruz CA 95064, United States of America
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13
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Choudhury S, Chaurasiya AK, Mondal AK, Rana B, Miura K, Takahashi H, Otani Y, Barman A. Voltage controlled on-demand magnonic nanochannels. SCIENCE ADVANCES 2020; 6:eaba5457. [PMID: 33008903 PMCID: PMC7852390 DOI: 10.1126/sciadv.aba5457] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 08/13/2020] [Indexed: 05/25/2023]
Abstract
Development of energy-efficient on-demand magnonic nanochannels (MNCs) can revolutionize on-chip data communication and processing. We have developed a dynamic MNC array by periodically tailoring perpendicular magnetic anisotropy using the electric field. Brillouin light scattering spectroscopy is used to probe the spin wave (SW) dispersion of MNCs formed by applying a static electric field at the CoFeB/MgO interface through the one-dimensional stripe-like array of indium tin oxide electrodes placed on top of Ta/CoFeB/MgO/Al2O3 heterostructures. Magnonic bands, consisting of two SW frequency modes, appear with a bandgap under the application of moderate gate voltage, which can be switched off by withdrawing the voltage. The experimental results are reproduced by plane wave method-based numerical calculations, and simulated SW mode profiles show propagating SWs through nanochannels with different magnetic properties. The anticrossing between these two modes gives rise to the observed magnonic bandgap.
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Affiliation(s)
- Samiran Choudhury
- Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700 106, India
| | - Avinash Kumar Chaurasiya
- Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700 106, India
| | - Amrit Kumar Mondal
- Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700 106, India
| | - Bivas Rana
- Center for Emergent Matter Science, RIKEN, 2-1 Hirosawa, Wako 351-0198, Japan
| | - Katsuya Miura
- Research and Development Group, Hitachi Ltd., 1-280 Higashi-koigakubo, Kokubunji-shi, Tokyo 185-8601, Japan
| | - Hiromasa Takahashi
- Research and Development Group, Hitachi Ltd., 1-280 Higashi-koigakubo, Kokubunji-shi, Tokyo 185-8601, Japan
| | - YoshiChika Otani
- Center for Emergent Matter Science, RIKEN, 2-1 Hirosawa, Wako 351-0198, Japan
- Institute for Solid State Physics, University of Tokyo, Kashiwa 277-8581, Japan
| | - Anjan Barman
- Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700 106, India.
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14
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Chen AP, Lin W, Chen J, Feng YP. Thickness and Ferroelectric Polarization Influence on Film Magnetic Anisotropy across a Multiferroic Material Interface. ACS APPLIED MATERIALS & INTERFACES 2020; 12:44317-44324. [PMID: 32894937 DOI: 10.1021/acsami.0c12048] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
The ferroelectric switching effect on perpendicular magnetic anisotropy is examined for the case of the BaTiO3/L10-CoFe interface through first-principles calculations of film magnetocrystalline anisotropy energy (MAE), both with the frozen-potential method and the second-order perturbation theory. The ferroelectric switching-MAE relationship is shown to have opposite trends for BaO- and TiO2-terminated interfaces because of the distinct orbital interaction mechanisms predominant in each termination configuration. The ferroelectric switching effect, changes in Fe-O bond lengths, and termination constitute three different contributors to MAE change, each with a different penetration depth into the CoFe film. The top surface CoFe atoms are shown to feature a high density of minority-spin 3dxz states, which could play a role in influencing the ferroelectric switching-MAE relationship in cases where the top surface undergoes modifications.
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Affiliation(s)
- Andy Paul Chen
- Department of Materials Science and Engineering, Case Western Reserve University, Cleveland, Ohio 44106, United States
- NUS Graduate School of Integrative Sciences and Engineering, National University of Singapore, Singapore 117456, Singapore
| | - Weinan Lin
- Department of Materials Science and Engineering, National University of Singapore, Singapore 117576, Singapore
| | - Jingsheng Chen
- Department of Materials Science and Engineering, National University of Singapore, Singapore 117576, Singapore
- NUS Graduate School of Integrative Sciences and Engineering, National University of Singapore, Singapore 117456, Singapore
| | - Yuan Ping Feng
- Department of Physics, National University of Singapore, Singapore 117576, Singapore
- NUS Graduate School of Integrative Sciences and Engineering, National University of Singapore, Singapore 117456, Singapore
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15
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Su Y, Zhang J, Hong J, You L. The effect of insertion layer on the perpendicular magnetic anisotropy and its electric-field-induced change at Fe/MgO interface: a first-principles investigation. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:454001. [PMID: 32679571 DOI: 10.1088/1361-648x/aba721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2020] [Accepted: 07/17/2020] [Indexed: 06/11/2023]
Abstract
The development of ultralow power and high density nonvolatile magnetic random access memory stimulates the search for promising materials in magnetic tunnel junction with large voltage-controlled magnetic anisotropy (VCMA) efficiency. In this work, we investigate the 4dand 5dtransition metal interlayer effect on perpendicular magnetic anisotropy (PMA) and VCMA at Fe/MgO interface by using first-principles calculations. Large PMA more than 11 mJ m-2is found at Fe/MgO interface with Pt insertion layer and the mechanism for PMA is clarified based on the second order perturbation theory. Furthermore, we find that the magnitude and the sign of VCMA efficiency are varied by introducing different insertions at Fe/MgO interface. The Re and Os interlayers lead to a sizable increase in both of the PMA and the VCMA coefficient. Our findings may further emphasize the essential importance of the interface structure on PMA and VCMA and may offer new material platforms for low-power consumption spintronic devices.
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Affiliation(s)
- Yurong Su
- School of Optical and Electronic Information, Huazhong University of Science and Technology, 430074 Wuhan, People's Republic of China
| | - Jia Zhang
- School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, 430074 Wuhan, People's Republic of China
| | - Jeongmin Hong
- School of Optical and Electronic Information, Huazhong University of Science and Technology, 430074 Wuhan, People's Republic of China
| | - Long You
- School of Optical and Electronic Information, Huazhong University of Science and Technology, 430074 Wuhan, People's Republic of China
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16
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Yamamoto T, Nozaki T, Imamura H, Tamaru S, Yakushiji K, Kubota H, Fukushima A, Yuasa S. Voltage-Driven Magnetization Switching Controlled by Microwave Electric Field Pumping. NANO LETTERS 2020; 20:6012-6017. [PMID: 32649831 DOI: 10.1021/acs.nanolett.0c02022] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We study the dynamic switching properties of a nanomagnet under microwave electric field pumping. The periodic modulation of an anisotropy field induced by microwave electric field pumping efficiently excites the uniform magnetization oscillation, allowing for precise control of magnetization switching. Accurate shaping of the pumping voltage waveform also enables us to investigate the transient reaction of magnetization to the relative phase difference of the pumping signal. We demonstrate both experimentally and theoretically the existence of a dead angle in which the uniform oscillation of magnetization is inhibited even though the microwave frequency itself satisfies the conditions of parametric excitation. Our results provide an energy-efficient way of manipulating ultrafast magnetization dynamics in nanomagnetic devices.
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Affiliation(s)
- Tatsuya Yamamoto
- National Institute of Advanced Industrial Science and Technology (AIST), Spintronics Research Center, Tsukuba, Ibaraki 305-8568, Japan
| | - Takayuki Nozaki
- National Institute of Advanced Industrial Science and Technology (AIST), Spintronics Research Center, Tsukuba, Ibaraki 305-8568, Japan
| | - Hiroshi Imamura
- National Institute of Advanced Industrial Science and Technology (AIST), Spintronics Research Center, Tsukuba, Ibaraki 305-8568, Japan
| | - Shingo Tamaru
- National Institute of Advanced Industrial Science and Technology (AIST), Spintronics Research Center, Tsukuba, Ibaraki 305-8568, Japan
| | - Kay Yakushiji
- National Institute of Advanced Industrial Science and Technology (AIST), Spintronics Research Center, Tsukuba, Ibaraki 305-8568, Japan
| | - Hitoshi Kubota
- National Institute of Advanced Industrial Science and Technology (AIST), Spintronics Research Center, Tsukuba, Ibaraki 305-8568, Japan
| | - Akio Fukushima
- National Institute of Advanced Industrial Science and Technology (AIST), Spintronics Research Center, Tsukuba, Ibaraki 305-8568, Japan
| | - Shinji Yuasa
- National Institute of Advanced Industrial Science and Technology (AIST), Spintronics Research Center, Tsukuba, Ibaraki 305-8568, Japan
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17
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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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18
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Tang M, Shen K, Xu S, Yang H, Hu S, Lü W, Li C, Li M, Yuan Z, Pennycook SJ, Xia K, Manchon A, Zhou S, Qiu X. Bulk Spin Torque-Driven Perpendicular Magnetization Switching in L1 0 FePt Single Layer. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e2002607. [PMID: 32596934 DOI: 10.1002/adma.202002607] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 06/04/2020] [Indexed: 06/11/2023]
Abstract
Due to its inherent superior perpendicular magnetocrystalline anisotropy, the FePt in L10 phase enables magnetic storage and memory devices with ultrahigh capacity. However, reversing the FePt magnetic state, and therefore encoding information, has proven to be extremely difficult. Here, it is demonstrated that an electric current can exert a large spin torque on an L10 FePt magnet, ultimately leading to reversible magnetization switching. The spin torque monotonically increases with increasing FePt thickness, exhibiting a bulk characteristic. Meanwhile, the spin torque effective fields and switching efficiency increase as the FePt approaches higher chemical ordering with stronger spin-orbit coupling. The symmetry breaking that generates spin torque within L10 FePt is shown to arise from an inherent structural gradient along the film normal direction. By artificially reversing the structural gradient, an opposite spin torque effect in L10 FePt is demonstrated. At last, the role of the disorder gradient in generating a substantial torque in a single ferromagnet is supported by theoretical calculations. These results will push forward the frontier of material systems for generating spin torques and will have a transformative impact on magnetic storage and spin memory devices with simple architecture, ultrahigh density, and readily application.
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Affiliation(s)
- Meng Tang
- Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology School of Physics Science and Engineering, Tongji University, Shanghai, 200092, China
| | - Ka Shen
- Department of Physics, Beijing Normal University, Beijing, 100875, China
| | - Shijie Xu
- Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology School of Physics Science and Engineering, Tongji University, Shanghai, 200092, China
| | - Huanglin Yang
- Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology School of Physics Science and Engineering, Tongji University, Shanghai, 200092, China
| | - Shuai Hu
- Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology School of Physics Science and Engineering, Tongji University, Shanghai, 200092, China
| | - Weiming Lü
- Spintronics Institute, University of Jinan, Jinan, 250022, China
- Condensed Matter Science and Technology Institute, School of Science, Harbin Institute of Technology, Harbin, 150081, China
| | - Changjian Li
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Mengsha Li
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Zhe Yuan
- Department of Physics, Beijing Normal University, Beijing, 100875, China
| | - Stephen J Pennycook
- Department of Materials Science and Engineering, National University of Singapore, Singapore, 117575, Singapore
| | - Ke Xia
- Beijing Computational Science Research Center, Beijing, 100193, China
| | - Aurelien Manchon
- Division of Physical Science and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955, Saudi Arabia
- Aix-Marseille Université, CNRS, CINaM, Marseille, 13288, France
| | - Shiming Zhou
- Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology School of Physics Science and Engineering, Tongji University, Shanghai, 200092, China
| | - Xuepeng Qiu
- Shanghai Key Laboratory of Special Artificial Microstructure Materials and Technology School of Physics Science and Engineering, Tongji University, Shanghai, 200092, China
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19
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Leon AO, Bauer GEW. Voltage- and temperature-dependent rare-earth dopant contribution to the interfacial magnetic anisotropy. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:404004. [PMID: 32498063 DOI: 10.1088/1361-648x/ab997c] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/26/2020] [Accepted: 06/04/2020] [Indexed: 06/11/2023]
Abstract
The control of magnetic materials and devices by voltages without electric currents holds the promise of power-saving nano-scale devices. Here we study the temperature-dependent voltage control of the magnetic anisotropy caused by rare-earth (RE) local moments at an interface between a magnetic metal and a non-magnetic insulator, such as Co|(RE)|MgO. Based on a Stevens operator representation of crystal and applied field effects, we find large dominantly quadrupolar intrinsic and field-induced interface anisotropies at room temperature. We suggest improved functionalities of transition metal tunnel junctions by dusting their interfaces with rare earths.
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Affiliation(s)
- Alejandro O Leon
- Departamento de Física, Facultad de Ciencias Naturales, Matemática y del Medio Ambiente, Universidad Tecnológica Metropolitana, Las Palmeras 3360, Ñuñoa 780-0003, Santiago, Chile
| | - Gerrit E W Bauer
- WPI-AIMR, Tohoku University, Sendai 980-8577, Japan
- Institute for Materials Research & CSRN, Tohoku University, Sendai 980-8577, Japan
- Zernike Institute for Advanced Materials, Groningen University, The Netherlands
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20
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Navarro-Senent C, Quintana A, Isarain-Chávez E, Weschke E, Yu P, Coll M, Pellicer E, Menéndez E, Sort J. Enhancing Magneto-Ionic Effects in Magnetic Nanostructured Films via Conformal Deposition of Nanolayers with Oxygen Acceptor/Donor Capabilities. ACS APPLIED MATERIALS & INTERFACES 2020; 12:14484-14494. [PMID: 32129067 DOI: 10.1021/acsami.9b19363] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Effective manipulation of the magnetic properties of nanostructured metallic alloys, exhibiting intergrain porosity (i.e., channels) and conformally coated with insulating oxide nanolayers, with an electric field is demonstrated. Nanostructured Co-Pt films are grown by electrodeposition (ED) and subsequently coated with either AlOx or HfOx by atomic layer deposition (ALD) to promote magneto-ionic effects (i.e., voltage-driven ion migration) during electrolyte gating. Pronounced variations in coercivity (HC) and magnetic moment at saturation (mS) are found at room temperature after biasing the heterostructures. The application of a negative voltage results in a decrease of HC and an increase of mS, whereas the opposite trend is achieved for positive voltages. Although magneto-ionic phenomena are already observed in uncoated Co-Pt films (because of the inherent presence of oxygen), the ALD oxide nanocoatings serve to drastically enhance the magneto-ionic effects because of partially reversible oxygen migration, driven by voltage, across the interface between AlOx or HfOx and the nanostructured Co-Pt film. Co-Pt/HfOx heterostructures exhibit the most significant magneto-electric response at negative voltages, with an increase of mS up to 76% and a decrease of HC by 58%. The combination of a nanostructured magnetic alloy and a skinlike insulating oxide nanocoating is shown to be appealing to enhance magneto-ionic effects, potentially enabling electrolyte-gated magneto-ionic technology.
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Affiliation(s)
- Cristina Navarro-Senent
- Departament de Fı́sica, Universitat Autònoma de Barcelona, E-08193 Cerdanyola del Vallès, Spain
| | - Alberto Quintana
- Departament de Fı́sica, Universitat Autònoma de Barcelona, E-08193 Cerdanyola del Vallès, Spain
- Department of Physics, Georgetown University, 20057 Washington, D.C., United States
| | - Eloy Isarain-Chávez
- Departament de Fı́sica, Universitat Autònoma de Barcelona, E-08193 Cerdanyola del Vallès, Spain
| | - Eugen Weschke
- Helmholtz-Zentrum Berlin für Materialien und Energie, Albert-Einstein-Strasse 15, D-12489 Berlin, Germany
| | - Pengmei Yu
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, E-08193 Bellaterra, Catalonia, Spain
| | - Mariona Coll
- Institut de Ciència de Materials de Barcelona (ICMAB-CSIC), Campus UAB, E-08193 Bellaterra, Catalonia, Spain
| | - Eva Pellicer
- Departament de Fı́sica, Universitat Autònoma de Barcelona, E-08193 Cerdanyola del Vallès, Spain
| | - Enric Menéndez
- Departament de Fı́sica, Universitat Autònoma de Barcelona, E-08193 Cerdanyola del Vallès, Spain
| | - Jordi Sort
- Departament de Fı́sica, Universitat Autònoma de Barcelona, E-08193 Cerdanyola del Vallès, Spain
- Institució Catalana de Recerca i Estudis Avançats (ICREA), Passeig de Lluís Companys 23, E-08010 Barcelona, Spain
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21
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Arras R, Cherifi-Hertel S. Polarization Control of the Interface Ferromagnetic to Antiferromagnetic Phase Transition in Co/Pb(Zr,Ti)O 3. ACS APPLIED MATERIALS & INTERFACES 2019; 11:34399-34407. [PMID: 31456387 DOI: 10.1021/acsami.9b08906] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Based on first-principles calculations, we predict the polarization control of the interfacial magnetic phase and a giant electronically driven magnetoelectric coupling (MEC) in Co/PbZr0.25Ti0.75O3 (PZT)(001). The effect of Co oxidation at the interface shared with (Zr,Ti)O2-terminated PZT is evidenced. The magnetic phase of the oxidized Co interface layer is electrically switched from the ferromagnetic to the antiferromagnetic state by reversing the PZT polarization from upward to downward, respectively. A comparative study between oxidized and unoxidized Co/PZT interfaces shows that in oxidized Co/PZT bilayers, the variation of the interface spin moment upon polarization reversal exceeds that of unoxidized Co/PZT bilayers by about 1 order of magnitude. We define a surface MEC constant αS taking into account the polarization dependence of both the spin and orbital moments. In unoxidized Co/PZT bilayers, we obtain αS ≈ 2 × 10-10 G cm2 V-1, while a giant surface coupling αS ≈ 12 × 10-10 G cm2 V-1 is found in the case of oxidized Co/PZT. We demonstrate that the polarization control of the magnetocrystalline anisotropy via spin-orbit coupling is not only effective at the interface but it extends to the Co film despite the interface origin of the MEC. This study shows that tailoring the nature of atomic bonding and electron occupancies allows for improving the performance of functional interfaces, enabling an efficient electric field control of spin-orbit interactions. Moreover, the nonlocal character of this effect holds promising perspectives for the application of electronically driven interface MEC in spin-orbitronic devices.
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Affiliation(s)
- Rémi Arras
- CEMES , Université de Toulouse, CNRS , 29 rue Jeanne-Marvig , 31055 Toulouse , France
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22
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Vermeulen BF, Ciubotaru F, Popovici MI, Swerts J, Couet S, Radu IP, Stancu A, Temst K, Groeseneken G, Adelmann C, Martens KM. Ferroelectric Control of Magnetism in Ultrathin HfO 2\Co\Pt Layers. ACS APPLIED MATERIALS & INTERFACES 2019; 11:34385-34393. [PMID: 31449744 DOI: 10.1021/acsami.9b07973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The recent demonstration of ferroelectricity in ultrathin HfO2 has kickstarted a new wave of research into this material. HfO2 in the orthorhombic phase can be considered the first and only truly nanoscale ferroelectric material that is compatible with silicon-based nanoelectronics applications. In this article, we demonstrate the ferroelectric control of the magnetic properties of cobalt deposited on ultrathin aluminum-doped, atomic layer deposition-grown HfO2 (tHfO2 = 6.5 nm). The ferroelectric effect is shown to control the shape of the magnetic hysteresis, quantified here by the magnetic switching energy. Furthermore, the magnetic properties such as the remanence are modulated by up to 41%. We show that this modulation does not only correlate with the charge accumulation at the interface but also shows an additional component associated with the ferroelectric polarization switching. An in-depth analysis using first order reversal curves shows that the coercive and interaction field distributions of cobalt can be modulated up to, respectively, 5.8% and 10.5% with the ferroelectric polarization reversal.
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Affiliation(s)
- Bart F Vermeulen
- Laboratorium voor Halfgeleiderfysica , KU Leuven , 3001 Leuven , Belgium
- IMEC , Kapeldreef 75 , 3001 Leuven , Belgium
| | | | | | | | | | | | - Alexandru Stancu
- Faculty of Physics , Alexandru Ioan Cuza University of Iasi , Iasi 700506 , Romania
| | - Kristiaan Temst
- Instituut voor Kern-en Stralingsfysica , KU Leuven , 3001 Leuven , Belgium
| | - Guido Groeseneken
- IMEC , Kapeldreef 75 , 3001 Leuven , Belgium
- Department of Electrical Engineering , KU Leuven , 3001 Leuven , Belgium
| | | | - Koen M Martens
- Laboratorium voor Halfgeleiderfysica , KU Leuven , 3001 Leuven , Belgium
- IMEC , Kapeldreef 75 , 3001 Leuven , Belgium
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23
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Son K, Ryu G, Jeong HH, Fink L, Merz M, Nagel P, Schuppler S, Richter G, Goering E, Schütz G. Superior Magnetic Performance in FePt L1 0 Nanomaterials. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2019; 15:e1902353. [PMID: 31257719 DOI: 10.1002/smll.201902353] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/09/2019] [Revised: 06/17/2019] [Indexed: 06/09/2023]
Abstract
The discovery of the high maximum energy product of 59 MGOe for NdFeB magnets is a breakthrough in the development of permanent magnets with a tremendous impact in many fields of technology. This value is still the world record, for 40 years. This work reports on a reliable and robust route to realize nearly perfectly ordered L10 -phase FePt nanoparticles, leading to an unprecedented energy product of 80 MGOe at room temperature. Furthermore, with a 3 nm Au coverage, the magnetic polarization of these nanomagnets can be enhanced by 25% exceeding 1.8 T. This exceptional magnetization and anisotropy is confirmed by using multiple imaging and spectroscopic methods, which reveal highly consistent results. Due to the unprecedented huge energy product, this material can be envisaged as a new advanced basic magnetic component in modern micro and nanosized devices.
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Affiliation(s)
- Kwanghyo Son
- Max Planck Institute for Intelligent Systems, Heisenbergstr. 3, D-70569, Stuttgart, Germany
| | - Gihun Ryu
- Max Planck Institute for Solid State Research, Heisenbergstr. 1, D-70569, Stuttgart, Germany
- Max Planck Institute for Chemical Physics of Solids, Nöthnitzerstr. 40, D-01187, Dresden, Germany
| | - Hyeon-Ho Jeong
- Max Planck Institute for Intelligent Systems, Heisenbergstr. 3, D-70569, Stuttgart, Germany
| | - Lukas Fink
- Max Planck Institute for Intelligent Systems, Heisenbergstr. 3, D-70569, Stuttgart, Germany
| | - Michael Merz
- Karlsruhe Institute of Technology, Institute for Solid-State Physics, D-76021, Karlsruhe, Germany
| | - Peter Nagel
- Karlsruhe Institute of Technology, Institute for Solid-State Physics, D-76021, Karlsruhe, Germany
| | - Stefan Schuppler
- Karlsruhe Institute of Technology, Institute for Solid-State Physics, D-76021, Karlsruhe, Germany
| | - Gunther Richter
- Max Planck Institute for Intelligent Systems, Heisenbergstr. 3, D-70569, Stuttgart, Germany
| | - Eberhard Goering
- Max Planck Institute for Intelligent Systems, Heisenbergstr. 3, D-70569, Stuttgart, Germany
| | - Gisela Schütz
- Max Planck Institute for Intelligent Systems, Heisenbergstr. 3, D-70569, Stuttgart, Germany
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24
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Lu J, Chen G, Luo W, Íñiguez J, Bellaiche L, Xiang H. Ferroelectricity with Asymmetric Hysteresis in Metallic LiOsO_{3} Ultrathin Films. PHYSICAL REVIEW LETTERS 2019; 122:227601. [PMID: 31283287 DOI: 10.1103/physrevlett.122.227601] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/14/2018] [Revised: 03/21/2019] [Indexed: 06/09/2023]
Abstract
Bulk LiOsO_{3} was experimentally identified as a "ferroelectric" metal where polar distortions coexist with metallicity [Shi et al., Nat. Mater. 12, 1024 (2013)NMAACR1476-112210.1038/nmat3754]. It is generally believed that polar displacements in a ferroelectric metal cannot be switched by an external electric field. Here, via comprehensive density functional theory calculations, we demonstrate that a two-unit cell-thick LiOsO_{3} thin film exhibits a ferroelectric ground state having an out-of-plane electric dipole moment that can be switched by an external electric field. Moreover, its dipole moment-versus-electric field hysteresis loop is asymmetric because only surface Li ions' displacements are reversed by the external electric field whereas the field-induced force on inner Li atoms is nearly fully screened by itinerant electrons. As a relevant by-product of our study, we also extend the concept of "Born effective charge" to finite metallic systems, and show its usefulness to rationalize the observed effects.
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Affiliation(s)
- Jinlian Lu
- Key Laboratory of Computational Physical Sciences (Ministry of Education), State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200433, China
- Department of Physics, Yancheng Institute of Technology, Yancheng, 224051, China
| | - Gong Chen
- Department of Physics, University of Science and Technology of China, Hefei 230026, China
| | - Wei Luo
- Key Laboratory of Computational Physical Sciences (Ministry of Education), State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200433, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
| | - Jorge Íñiguez
- Materials Research and Technology Department, Luxembourg Institute of Science and Technology, 5 Avenue des Hauts-Fourneaux, L-4362, Esch/Alzette, Luxembourg
- Physics and Materials Science Research Unit, University of Luxembourg, 41 Rue du Brill, L-4422 Belvaux, Luxembourg
| | - Laurent Bellaiche
- Physics Department and Institute for Nanoscience and Engineering University of Arkansas, Fayetteville, Arkansas 72701, USA
| | - Hongjun Xiang
- Key Laboratory of Computational Physical Sciences (Ministry of Education), State Key Laboratory of Surface Physics, and Department of Physics, Fudan University, Shanghai 200433, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
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Nozaki T, Yamamoto T, Miwa S, Tsujikawa M, Shirai M, Yuasa S, Suzuki Y. Recent Progress in the Voltage-Controlled Magnetic Anisotropy Effect and the Challenges Faced in Developing Voltage-Torque MRAM. MICROMACHINES 2019; 10:E327. [PMID: 31096668 PMCID: PMC6562605 DOI: 10.3390/mi10050327] [Citation(s) in RCA: 60] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/24/2019] [Revised: 05/10/2019] [Accepted: 05/12/2019] [Indexed: 12/04/2022]
Abstract
The electron spin degree of freedom can provide the functionality of "nonvolatility" in electronic devices. For example, magnetoresistive random access memory (MRAM) is expected as an ideal nonvolatile working memory, with high speed response, high write endurance, and good compatibility with complementary metal-oxide-semiconductor (CMOS) technologies. However, a challenging technical issue is to reduce the operating power. With the present technology, an electrical current is required to control the direction and dynamics of the spin. This consumes high energy when compared with electric-field controlled devices, such as those that are used in the semiconductor industry. A novel approach to overcome this problem is to use the voltage-controlled magnetic anisotropy (VCMA) effect, which draws attention to the development of a new type of MRAM that is controlled by voltage (voltage-torque MRAM). This paper reviews recent progress in experimental demonstrations of the VCMA effect. First, we present an overview of the early experimental observations of the VCMA effect in all-solid state devices, and follow this with an introduction of the concept of the voltage-induced dynamic switching technique. Subsequently, we describe recent progress in understanding of physical origin of the VCMA effect. Finally, new materials research to realize a highly-efficient VCMA effect and the verification of reliable voltage-induced dynamic switching with a low write error rate are introduced, followed by a discussion of the technical challenges that will be encountered in the future development of voltage-torque MRAM.
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Affiliation(s)
- Takayuki Nozaki
- National Institute of Advanced Industrial Science and Technology (AIST), Spintronics Research Center, Tsukuba, Ibaraki 305-8568, Japan.
| | - Tatsuya Yamamoto
- National Institute of Advanced Industrial Science and Technology (AIST), Spintronics Research Center, Tsukuba, Ibaraki 305-8568, Japan.
| | - Shinji Miwa
- The Institute of Solid State Physics, The University of Tokyo, Kashiwa, Chiba 277-8531, Japan.
- Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan.
| | - Masahito Tsujikawa
- Research Institute of Electrical Communication, Tohoku University, Sendai, Miyagi 980-8577, Japan.
| | - Masafumi Shirai
- Research Institute of Electrical Communication, Tohoku University, Sendai, Miyagi 980-8577, Japan.
| | - Shinji Yuasa
- National Institute of Advanced Industrial Science and Technology (AIST), Spintronics Research Center, Tsukuba, Ibaraki 305-8568, Japan.
| | - Yoshishige Suzuki
- National Institute of Advanced Industrial Science and Technology (AIST), Spintronics Research Center, Tsukuba, Ibaraki 305-8568, Japan.
- Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan.
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26
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Ma C, Zhang X, Xia J, Ezawa M, Jiang W, Ono T, Piramanayagam SN, Morisako A, Zhou Y, Liu X. Electric Field-Induced Creation and Directional Motion of Domain Walls and Skyrmion Bubbles. NANO LETTERS 2019; 19:353-361. [PMID: 30537837 DOI: 10.1021/acs.nanolett.8b03983] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Magnetization dynamics driven by an electric field could provide long-term benefits to information technologies because of its ultralow power consumption. Meanwhile, the Dzyaloshinskii-Moriya interaction in interfacially asymmetric multilayers consisting of ferromagnetic and heavy-metal layers can stabilize topological spin textures, such as chiral domain walls, skyrmions, and skyrmion bubbles. These topological spin textures can be controlled by an electric field and hold promise for building advanced spintronic devices. Here, we present an experimental and numerical study on the electric field-induced creation and directional motion of topological spin textures in magnetic multilayer films and racetracks with thickness gradient and interfacial Dzyaloshinskii-Moriya interaction at room temperature. We find that the electric field-induced directional motion of chiral domain wall is accompanied by the creation of skyrmion bubbles at certain conditions. We also demonstrate that the electric field variation can induce motion of skyrmion bubbles. Our findings may provide opportunities for developing skyrmion-based devices with ultralow power consumption.
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Affiliation(s)
- Chuang Ma
- Department of Electrical and Computer Engineering , Shinshu University , 4-17-1 Wakasato , Nagano 380-8553 , Japan
| | - Xichao Zhang
- School of Science and Engineering , The Chinese University of Hong Kong , Shenzhen , Guangdong 518172 , China
| | - Jing Xia
- School of Science and Engineering , The Chinese University of Hong Kong , Shenzhen , Guangdong 518172 , China
| | - Motohiko Ezawa
- Department of Applied Physics , The University of Tokyo , 7-3-1 Hongo , Tokyo 113-8656 , Japan
| | - Wanjun Jiang
- State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics , Tsinghua University , Beijing 100084 , China
| | - Teruo Ono
- Institute for Chemical Research , Kyoto University , Gokasho, Uji , Kyoto 611-0011 , Japan
| | - S N Piramanayagam
- School of Physical and Mathematical Sciences , Nanyang Technological University , 637371 , Singapore
| | - Akimitsu Morisako
- Department of Electrical and Computer Engineering , Shinshu University , 4-17-1 Wakasato , Nagano 380-8553 , Japan
| | - Yan Zhou
- School of Science and Engineering , The Chinese University of Hong Kong , Shenzhen , Guangdong 518172 , China
| | - Xiaoxi Liu
- Department of Electrical and Computer Engineering , Shinshu University , 4-17-1 Wakasato , Nagano 380-8553 , Japan
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27
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Zhong G, An F, Bitla Y, Wang J, Zhong X, Yu J, Gao W, Zhang Y, Tan C, Ou Y, Jiang J, Hsieh YH, Pan X, Xie S, Chu YH, Li J. Deterministic, Reversible, and Nonvolatile Low-Voltage Writing of Magnetic Domains in Epitaxial BaTiO 3/Fe 3O 4 Heterostructure. ACS NANO 2018; 12:9558-9567. [PMID: 30138564 DOI: 10.1021/acsnano.8b05284] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The ability to electrically write magnetic bits is highly desirable for future magnetic memories and spintronic devices, though fully deterministic, reversible, and nonvolatile switching of magnetic moments by electric field remains elusive despite extensive research. In this work, we develop a concept to electrically switch magnetization via polarization modulated oxygen vacancies, and we demonstrate the idea in a multiferroic epitaxial heterostructure of BaTiO3/Fe3O4 fabricated by pulsed laser deposition. The piezoelectricity and ferroelectricity of BaTiO3 have been confirmed by macro- and microscale measurements, for which Fe3O4 serves as the top electrode for switching the polarization. X-ray absorption spectroscopy and X-ray magnetic circular dichroism spectra indicate a mixture of Fe2+ and Fe3+ at O h sites and Fe3+ at T d sites in Fe3O4, while the room-temperature magnetic domains of Fe3O4 are revealed by microscopic magnetic force microscopy measurements. It is demonstrated that the magnetic domains of Fe3O4 can be switched by not only magnetic fields but also electric fields in a deterministic, reversible, and nonvolatile manner, wherein polarization reversal by electric field modulates the oxygen vacancy distribution in Fe3O4, and thus its magnetic state, making it attractive for electrically written magnetic memories.
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Affiliation(s)
- Gaokuo Zhong
- Shenzhen Key Laboratory of Nanobiomechanics, Shenzhen Institutes of Advanced Technology , Chinese Academy of Sciences , Shenzhen 518055 , Guangdong , China
- Key Laboratory of Low Dimensional Materials and Application Technology of Ministry of Education, and School of Materials Science and Engineering , Xiangtan University , Xiangtan 411105 , Hunan , China
- Department of Materials Science and Engineering , National Chiao Tung University , Hsinchu 30010 , Taiwan
- Department of Chemical Engineering and Materials Science , University of California, Irvine , Irvine 92697 , California , United States
| | - Feng An
- Key Laboratory of Low Dimensional Materials and Application Technology of Ministry of Education, and School of Materials Science and Engineering , Xiangtan University , Xiangtan 411105 , Hunan , China
| | - Yugandhar Bitla
- Department of Physics , Indian Institute of Science , Bengaluru 560012 , India
| | - Jinbin Wang
- Key Laboratory of Low Dimensional Materials and Application Technology of Ministry of Education, and School of Materials Science and Engineering , Xiangtan University , Xiangtan 411105 , Hunan , China
| | - Xiangli Zhong
- Key Laboratory of Low Dimensional Materials and Application Technology of Ministry of Education, and School of Materials Science and Engineering , Xiangtan University , Xiangtan 411105 , Hunan , China
| | - Junxi Yu
- Shenzhen Key Laboratory of Nanobiomechanics, Shenzhen Institutes of Advanced Technology , Chinese Academy of Sciences , Shenzhen 518055 , Guangdong , China
- Key Laboratory of Low Dimensional Materials and Application Technology of Ministry of Education, and School of Materials Science and Engineering , Xiangtan University , Xiangtan 411105 , Hunan , China
| | - Wenpei Gao
- Department of Chemical Engineering and Materials Science , University of California, Irvine , Irvine 92697 , California , United States
| | - Yi Zhang
- Department of Chemical Engineering and Materials Science , University of California, Irvine , Irvine 92697 , California , United States
| | - Congbing Tan
- Key Laboratory of Low Dimensional Materials and Application Technology of Ministry of Education, and School of Materials Science and Engineering , Xiangtan University , Xiangtan 411105 , Hunan , China
| | - Yun Ou
- Shenzhen Key Laboratory of Nanobiomechanics, Shenzhen Institutes of Advanced Technology , Chinese Academy of Sciences , Shenzhen 518055 , Guangdong , China
| | - Jie Jiang
- Key Laboratory of Low Dimensional Materials and Application Technology of Ministry of Education, and School of Materials Science and Engineering , Xiangtan University , Xiangtan 411105 , Hunan , China
| | - Ying-Hui Hsieh
- Department of Materials Science and Engineering , National Chiao Tung University , Hsinchu 30010 , Taiwan
| | - Xiaoqing Pan
- Department of Chemical Engineering and Materials Science , University of California, Irvine , Irvine 92697 , California , United States
| | - Shuhong Xie
- Key Laboratory of Low Dimensional Materials and Application Technology of Ministry of Education, and School of Materials Science and Engineering , Xiangtan University , Xiangtan 411105 , Hunan , China
| | - Ying-Hao Chu
- Department of Materials Science and Engineering , National Chiao Tung University , Hsinchu 30010 , Taiwan
| | - Jiangyu Li
- Shenzhen Key Laboratory of Nanobiomechanics, Shenzhen Institutes of Advanced Technology , Chinese Academy of Sciences , Shenzhen 518055 , Guangdong , China
- Department of Mechanical Engineering , University of Washington , Seattle 98195 , Washington , United States
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28
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Voltage-Controlled Magnetic Anisotropy in Fe 1-xCo x/Pd/MgO system. Sci Rep 2018; 8:10362. [PMID: 29985395 PMCID: PMC6037784 DOI: 10.1038/s41598-018-28445-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2018] [Accepted: 06/22/2018] [Indexed: 11/18/2022] Open
Abstract
Voltage-controlled magnetic anisotropy (VCMA) in an epitaxially grown Fe/Fe1−xCox/Pd/MgO system was investigated using spin-wave spectroscopy. The spin-wave resonant frequency linearly depended on the bias-voltage. The resonant-frequency shift increased with the Co fraction in Fe1−xCox/Pd. We achieved a VCMA of approximately 250 fJ/Vm at the Co/Pd/MgO region.
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Yamada KT, Suzuki M, Pradipto AM, Koyama T, Kim S, Kim KJ, Ono S, Taniguchi T, Mizuno H, Ando F, Oda K, Kakizakai H, Moriyama T, Nakamura K, Chiba D, Ono T. Microscopic Investigation into the Electric Field Effect on Proximity-Induced Magnetism in Pt. PHYSICAL REVIEW LETTERS 2018; 120:157203. [PMID: 29756866 DOI: 10.1103/physrevlett.120.157203] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2017] [Indexed: 06/08/2023]
Abstract
Electric field effects on magnetism in metals have attracted widespread attention, but the microscopic mechanism is still controversial. We experimentally show the relevancy between the electric field effect on magnetism and on the electronic structure in Pt in a ferromagnetic state using element-specific measurements: x-ray magnetic circular dichroism (XMCD) and x-ray absorption spectroscopy (XAS). Electric fields are applied to the surface of ultrathin metallic Pt, in which a magnetic moment is induced by the ferromagnetic proximity effect resulting from a Co underlayer. XMCD and XAS measurements performed under the application of electric fields reveal that both the spin and orbital magnetic moments of Pt atoms are electrically modulated, which can be explained not only by the electric-field-induced shift of the Fermi level but also by the change in the orbital hybridizations.
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Affiliation(s)
- K T Yamada
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - M Suzuki
- Japan Synchrotron Radiation Research Institute, Sayo, Hyogo 679-5198, Japan
| | - A-M Pradipto
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
- Department of Physics Engineering, Mie University, Tsu, Mie 514-8507, Japan
| | - T Koyama
- Department of Applied Physics, The University of Tokyo, Bunkyo, Tokyo 113-8656, Japan
| | - S Kim
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - K-J Kim
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - S Ono
- Central Research Institute of Electric Power Industry, Yokosuka, Kanagawa 240-0196, Japan
| | - T Taniguchi
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - H Mizuno
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - F Ando
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - K Oda
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - H Kakizakai
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - T Moriyama
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
| | - K Nakamura
- Department of Physics Engineering, Mie University, Tsu, Mie 514-8507, Japan
| | - D Chiba
- Department of Applied Physics, The University of Tokyo, Bunkyo, Tokyo 113-8656, Japan
| | - T Ono
- Institute for Chemical Research, Kyoto University, Uji, Kyoto 611-0011, Japan
- Center for Spintronics Research Network (CSRN), Graduate School of Engineering Science, Osaka University, Toyonaka, Osaka 560-8531, Japan
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