1
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Rana B, Otani Y. Anisotropy of magnetic damping in Ta/CoFeB/MgO heterostructures. Sci Rep 2023; 13:8532. [PMID: 37237132 DOI: 10.1038/s41598-023-35739-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Accepted: 05/23/2023] [Indexed: 05/28/2023] Open
Abstract
Magnetic damping controls the performance and operational speed of many spintronics devices. Being a tensor quantity, the damping in magnetic thin films often shows anisotropic behavior with the magnetization orientation. Here, we have studied the anisotropy of damping in Ta/CoFeB/MgO heterostructures, deposited on thermally oxidized Si substrates, as a function of the orientation of magnetization. By performing ferromagnetic resonance (FMR) measurements based on spin pumping and inverse spin Hall effect (ISHE), we extract the damping parameter in those films and find that the anisotropy of damping contains four-fold and two-fold anisotropy terms. We infer that four-fold anisotropy originates from two-magnon scattering (TMS). By studying reference Ta/CoFeB/MgO films, deposited on LiNbO3 substrates, we find that the two-fold anisotropy is correlated with in-plane magnetic anisotropy (IMA) of the films, suggesting its origin as the anisotropy in bulk spin-orbit coupling (SOC) of CoFeB film. We conclude that when IMA is very small, it's correlation with two-fold anisotropy cannot be experimentally identified. However, as IMA increases, it starts to show a correlation with two-fold anisotropy in damping. These results will be beneficial for designing future spintronics devices.
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Affiliation(s)
- Bivas Rana
- Institute of Spintronics and Quantum Information, Faculty of Physics, Adam Mickiewicz University in Poznań, Uniwersytetu Poznanskiego 2, 61-614, Poznan, Poland.
- Center for Emergent Matter Science, RIKEN, 2-1 Hirosawa, Wako, 351-0198, 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, Chiba, 277-8581, Japan
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2
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Seifu D, Peng Q, Sze K, Hou J, Gao F, Lan Y. Electromagnetic Radiation Effects on MgO-Based Magnetic Tunnel Junctions: A Review. Molecules 2023; 28:molecules28104151. [PMID: 37241892 DOI: 10.3390/molecules28104151] [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: 10/20/2022] [Revised: 05/12/2023] [Accepted: 05/13/2023] [Indexed: 05/28/2023] Open
Abstract
Magnetic tunnel junctions (MTJs) have been widely utilized in sensitive sensors, magnetic memory, and logic gates due to their tunneling magnetoresistance. Moreover, these MTJ devices have promising potential for renewable energy generation and storage. Compared with Si-based devices, MTJs are more tolerant to electromagnetic radiation. In this review, we summarize the functionalities of MgO-based MTJ devices under different electromagnetic irradiation environments, with a focus on gamma-ray radiation. We explore the effects of these radiation exposures on the MgO tunnel barriers, magnetic layers, and interfaces to understand the origin of their tolerance. This review enhances our knowledge of the radiation tolerance of MgO-based MTJs, improves the design of these MgO-based MTJ devices with better tolerances, and provides information to minimize the risks of irradiation under various irradiation environments. This review starts with an introduction to MTJs and irradiation backgrounds, followed by the fundamental properties of MTJ materials, such as the MgO barrier and magnetic layers. Then, we review and discuss the MTJ materials and devices' radiation tolerances under different irradiation environments, including high-energy cosmic radiation, gamma-ray radiation, and lower-energy electromagnetic radiation (X-ray, UV-vis, infrared, microwave, and radiofrequency electromagnetic radiation). In conclusion, we summarize the radiation effects based on the published literature, which might benefit material design and protection.
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Affiliation(s)
- Dereje Seifu
- Department of Physics and Engineering Physics, Morgan State University, Baltimore, MD 21251, USA
| | - Qing Peng
- Physics Department, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia
- K. A. CARE Energy Research and Innovation Center at Dhahran, Dhahran 31261, Saudi Arabia
- Hydrogen and Energy Storage Center, King Fahd University of Petroleum and Minerals, Dhahran 31261, Saudi Arabia
| | - Kit Sze
- Department of Physics and Engineering Physics, Morgan State University, Baltimore, MD 21251, USA
| | - Jie Hou
- School of Materials Science and Engineering, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | - Fei Gao
- Nuclear Engineering and Radiological Sciences, University of Michigan, Ann Arbor, MI 48109, USA
| | - Yucheng Lan
- Department of Physics and Engineering Physics, Morgan State University, Baltimore, MD 21251, USA
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3
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Lyu D, Shoup JE, Huang D, García-Barriocanal J, Jia Q, Echtenkamp W, Rojas GA, Yu G, Zink BR, Wang X, Gopman DB, Wang JP. Sputtered L1 0-FePd and its Synthetic Antiferromagnet on Si/SiO 2 Wafers for Scalable Spintronics. ADVANCED FUNCTIONAL MATERIALS 2023; 23:10.1002/adfm.202214201. [PMID: 37200959 PMCID: PMC10190167 DOI: 10.1002/adfm.202214201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2022] [Indexed: 05/20/2023]
Abstract
As a promising alternative to the mainstream CoFeB/MgO system with interfacial perpendicular magnetic anisotropy (PMA), L10-FePd and its synthetic antiferromagnet (SAF) structure with large crystalline PMA can support spintronic devices with sufficient thermal stability at sub-5 nm sizes. However, the compatibility requirement of preparing L10-FePd thin films on Si/SiO2 wafers is still unmet. In this paper, we prepare high-quality L10-FePd and its SAF on Si/SiO2 wafers by coating the amorphous SiO2 surface with an MgO(001) seed layer. The prepared L10-FePd single layer and SAF stack are highly (001)-textured, showing strong PMA, low damping, and sizeable interlayer exchange coupling, respectively. Systematic characterizations, including advanced X-ray diffraction measurement and atomic resolution-scanning transmission electron microscopy, are conducted to explain the outstanding performance of L10-FePd layers. A fully-epitaxial growth that starts from MgO seed layer, induces the (001) texture of L10-FePd, and extends through the SAF spacer is observed. This study makes the vision of scalable spintronics more practical.
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Affiliation(s)
- Deyuan Lyu
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN 55455, USA
| | - Jenae E Shoup
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Dingbin Huang
- Department of Mechanical Engineering, University of Minnesota, Minneapolis, MN 55455, USA
| | | | - Qi Jia
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN 55455, USA
| | - William Echtenkamp
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN 55455, USA
| | - Geoffrey A Rojas
- Characterization Facility, University of Minnesota, Minneapolis, MN 55455, USA
| | - Guichuan Yu
- Characterization Facility, University of Minnesota, Minneapolis, MN 55455, USA
| | - Brandon R Zink
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN 55455, USA
| | - Xiaojia Wang
- Department of Mechanical Engineering, University of Minnesota, Minneapolis, MN 55455, USA
| | - Daniel B Gopman
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - Jian-Ping Wang
- Department of Electrical and Computer Engineering, University of Minnesota, Minneapolis, MN 55455, USA
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4
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Control of crystallization and magnetic properties of CoFeB by boron concentration. Sci Rep 2022; 12:4549. [PMID: 35296734 PMCID: PMC8927602 DOI: 10.1038/s41598-022-08407-6] [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: 10/25/2021] [Accepted: 03/02/2022] [Indexed: 11/08/2022] Open
Abstract
Controlling the crystallinity of CoFeB is the most essential issue for designing various spintronics devices. Here we show the microstructure and magnetic properties of MgO/CoFeB/MgO structures for various boron concentration. We present the effect of boron on the crystallinity of CoFeB into two categories: the critical boron concentration (5 ~ 6%) at which CoFeB crystallizes and the effect of remaining boron (0 ~ 5%) in the crystallized CoFeB. And the trends of the saturation magnetization, exchange stiffness, exchange length, domain wall energy and Gilbert damping constant according to the boron concentration are provided. Abrupt variation of properties near the critical boron concentration (5 ~ 6%) and a noticeable change in the crystallized CoFeB (0 ~ 5%) are confirmed, revealing a clear causal relationship with the structural analysis. These results propose that the crystallization, microstructure, and major magnetic properties of CoFeB are governed by the amount of boron, and emphasize the need for delicate control of boron concentration.
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Lu H, Guo Y, Robertson J. Ab Initio Study of Hexagonal Boron Nitride as the Tunnel Barrier in Magnetic Tunnel Junctions. ACS APPLIED MATERIALS & INTERFACES 2021; 13:47226-47235. [PMID: 34559966 DOI: 10.1021/acsami.1c13583] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
Two-dimensional hexagonal boron nitride (h-BN) is studied as a tunnel barrier in magnetic tunnel junctions (MTJs) as a possible alternative to MgO. The tunnel magnetoresistance (TMR) of such MTJs is calculated as a function of whether the interface involves the chemi- or physisorptive site of h-BN atoms on the metal electrodes, Fe, Co, or Ni. It is found that the physisorptive site on average produces higher TMR values, whereas the chemisorptive site has the greater binding energy but lower TMR. It is found that alloying the electrodes with an inert metal-like Pt can induce the preferred absorption site on Co to become a physisorptive site, enabling a higher TMR value. It is found that the choice of physisorptive sites of each element gives more Schottky-like dependence of their Schottky barrier heights on the metal work function.
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Affiliation(s)
- Haichang Lu
- School of Integrated Circuit Science and Engineering, Beihang University, Beijing 100191, China
- Engineering Department, Cambridge University, Cambridge CB2 1PZ, U.K
| | - Yuzheng Guo
- Engineering Department, Cambridge University, Cambridge CB2 1PZ, U.K
- School of Engineering, Swansea University, Swansea SA1 8EN, U.K
| | - John Robertson
- Engineering Department, Cambridge University, Cambridge CB2 1PZ, U.K
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6
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Wang H, Lin N, Xu R, Yu Y, Zhao X. First principles studies of electronic, mechanical and optical properties of Cr-doped cubic ZrO2. Chem Phys 2020. [DOI: 10.1016/j.chemphys.2020.110972] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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7
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Rana B, Miura K, Takahashi H, Otani Y. Underlayer material dependent symmetric and asymmetric behavior of voltage-controlled magnetic anisotropy in CoFeB films. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2020; 32:414002. [PMID: 32503010 DOI: 10.1088/1361-648x/ab99eb] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/04/2020] [Accepted: 06/05/2020] [Indexed: 06/11/2023]
Abstract
Voltage-controlled magnetic anisotropy (VCMA), observed at the interfaces of ultrathin ferromagnetic metallic films and oxide layer, has proven to be a useful tool for the development of all-electric field controlled spintronics devices. Here, we have studied the symmetric and asymmetric behavior of VCMA in CoFeB/MgO heterostructures, grown on different underlayer materials, by measuring ferromagnetic resonance using spin pumping and inverse spin Hall effect technique. We observe symmetric behavior of VCMA in CoFeB films with Ta underlayer, whereas a systematic transformation from symmetric to asymmetric behavior of VCMA with decreasing CoFeB thickness is observed for Pt underlayer. We speculate that the increased interfacial roughness, defects and strain of ultrathin CoFeB films with Pt buffer layer probably leads to the complicated band structure at CoFeB/MgO interface resulting in asymmetric behavior of VCMA. The observed symmetric behavior of VCMA in control samples justifies the role of interfacial roughness, defects and discards the role of oxide overlayer on the observed asymmetric behavior of VCMA in ultrathin CoFeB films.
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Affiliation(s)
- 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
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8
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Chen AP, Feng YP. Modulating Multiferroic Control of Magnetocrystalline Anisotropy Using 5d Transition Metal Capping Layers. ACS APPLIED MATERIALS & INTERFACES 2020; 12:25383-25389. [PMID: 32392027 DOI: 10.1021/acsami.0c02074] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Electric-field control of magnetocrystalline anisotropy energy (MAE) is important for the optimal performance of the tunnel junction components of the STT-MRAM. In such a device, a high MAE of the free magnetic layer improves storage robustness, whereas a low MAE is also useful to keep energy expenditure in the switching process at a minimum. Using the frozen potential method to calculate the MAE of the CoFe layer, the electric-field control of MAE in the BaTiO3/CoFe/(Hf, Ta, W, Re, Os, Ir, Pt, or Au) heterostructure is studied. Electric field tuning of MAE is determined to be possible through switching the direction of BaTiO3 ferroelectric polarization, although both the tuning effect and the MAE depend strongly on the choice of the 5d transition metal element in the capping layer. The results predict a complicated behavior of both MAE and the underlayer polarization effect as we progress down the 5d series of elements as the choice of the capping layer element. Using the second-order perturbation theoretical framework, this behavior can nevertheless be explained by mechanisms including CoFe/capping layer interface hybridization and 5d band-filling trends in the capping layer.
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Affiliation(s)
- Andy Paul Chen
- NUS Graduate School of Integrative Sciences and Engineering, National University of Singapore, Singapore 117456, Singapore
- Department of Materials Science and Engineering, Case Western Reserve University, Cleveland, Ohio 44106, United States
| | - Yuan Ping Feng
- NUS Graduate School of Integrative Sciences and Engineering, National University of Singapore, Singapore 117456, Singapore
- Department of Physics, National University of Singapore, Singapore 117576, Singapore
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9
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Chen Z, Zhang Y, Chu S, Sun R, Wang J, Chen J, Wei B, Zhang X, Zhou W, Shi Y, Wang Z. Grain Boundary Induced Ultralow Threshold Random Laser in a Single GaTe Flake. ACS APPLIED MATERIALS & INTERFACES 2020; 12:23323-23329. [PMID: 32337969 DOI: 10.1021/acsami.0c03419] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Random lasing is a lasing phenomenon realized in random media, and it has attracted a great deal of attention in recent years. An essential requirement for strong random lasing is to achieve strong and recurrent scattering among grain boundaries of a disordered structure. Herein, we report a random laser (RL) based on individual polycrystalline GaTe microflakes (MFs) with a lasing threshold of 4.15 kW cm-2, about 1-2 orders of magnitude lower than that of the reported single GaN microwire random laser. The strongly enhanced light scattering and trapping benefit from the reduced grain size in the polycrystalline GaTe MF, resulting in a ultralow threshold. We also investigate the dependence of spatially localized cavities' dimension on the pumping intensity profile and temperature. The findings provide a feasible route to realize RL with a low threshold and small size, opening up a new avenue in fulfilling many potential optoelectronic applications of RL.
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Affiliation(s)
- Zuxin Chen
- Engineering Technology Research Center for 2D Material Information Function Devices and Systems of Guangdong Province, International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education, Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen 518060, China
- International Iberian Nanotechnology Laboratory (INL), Av. Mestre Jose Veiga s/n, 4715-330 Braga, Portugal
| | - Yingjun Zhang
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science & Technology, Wuhan 430074, China
| | - Sheng Chu
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-Sen University, Guangzhou, 510275, China
| | - Rong Sun
- International Iberian Nanotechnology Laboratory (INL), Av. Mestre Jose Veiga s/n, 4715-330 Braga, Portugal
| | - Jun Wang
- Engineering Technology Research Center for 2D Material Information Function Devices and Systems of Guangdong Province, International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education, Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen 518060, China
- International Iberian Nanotechnology Laboratory (INL), Av. Mestre Jose Veiga s/n, 4715-330 Braga, Portugal
| | - Jiapeng Chen
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-Sen University, Guangzhou, 510275, China
| | - Bin Wei
- International Iberian Nanotechnology Laboratory (INL), Av. Mestre Jose Veiga s/n, 4715-330 Braga, Portugal
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics and Engineering, Sun Yat-Sen University, Guangzhou, 510275, China
| | - Xin Zhang
- International Iberian Nanotechnology Laboratory (INL), Av. Mestre Jose Veiga s/n, 4715-330 Braga, Portugal
| | - Weihang Zhou
- Wuhan National High Magnetic Field Center and School of Physics, Huazhong University of Science & Technology, Wuhan 430074, China
| | - Yumeng Shi
- Engineering Technology Research Center for 2D Material Information Function Devices and Systems of Guangdong Province, International Collaborative Laboratory of 2D Materials for Optoelectronics Science and Technology of Ministry of Education, Institute of Microscale Optoelectronics, Shenzhen University, Shenzhen 518060, China
| | - Zhongchang Wang
- International Iberian Nanotechnology Laboratory (INL), Av. Mestre Jose Veiga s/n, 4715-330 Braga, Portugal
- School of Materials and Energy, Southwest University, Chongqing 400715, China
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10
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Li X, Sasaki T, Grezes C, Wu D, Wong K, Bi C, Ong PV, Ebrahimi F, Yu G, Kioussis N, Wang W, Ohkubo T, Khalili Amiri P, Wang KL. Predictive Materials Design of Magnetic Random-Access Memory Based on Nanoscale Atomic Structure and Element Distribution. NANO LETTERS 2019; 19:8621-8629. [PMID: 31697502 DOI: 10.1021/acs.nanolett.9b03190] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Magnetic tunnel junctions (MTJs) capable of electrical read and write operations have emerged as a canonical building block for nonvolatile memory and logic. However, the cause of the widespread device properties found experimentally in various MTJ stacks, including tunneling magnetoresistance (TMR), perpendicular magnetic anisotropy (PMA), and voltage-controlled magnetic anisotropy (VCMA), remains elusive. Here, using high-resolution transmission electron microscopy and energy-dispersive X-ray spectroscopy, we found that the MTJ crystallization quality, boron diffusion out of the CoFeB fixed layer, and minimal oxidation of the fixed layer correlate with the TMR. As with the CoFeB free layer, seed layer diffusion into the free layer/MgO interface is negatively correlated with the interfacial PMA, whereas the metal-oxides concentrations in the free layer correlate with the VCMA. Combined with formation enthalpy and thermal diffusion analysis that can explain the evolution of element distribution from MTJ stack designs and annealing temperatures, we further established a predictive materials design framework to guide the complex design space explorations for high-performance MTJs. On the basis of this framework, we demonstrate experimentally high PMA and VCMA values of 1.74 mJ/m2 and 115 fJ/V·m-1 with annealing stability above 400 °C.
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Affiliation(s)
- Xiang Li
- Department of Electrical and Computer Engineering , University of California , Los Angeles , California 90095 , United States
- Inston, Inc. , Los Angeles , California 90095 , United States
- Department of Electrical Engineering , Stanford University , Stanford , California 94305 , United States
| | - Taisuke Sasaki
- National Institute for Materials Science (NIMS) , 1-2-1 Sengen , Tsukuba 305-0047 , Japan
| | - Cecile Grezes
- Department of Electrical and Computer Engineering , University of California , Los Angeles , California 90095 , United States
| | - Di Wu
- Department of Electrical and Computer Engineering , University of California , Los Angeles , California 90095 , United States
| | - Kin Wong
- Department of Electrical and Computer Engineering , University of California , Los Angeles , California 90095 , United States
| | - Chong Bi
- Department of Physics , University of Arizona , Tucson , Arizona 85721 , United States
| | - Phuong-Vu Ong
- Department of Physics and Astronomy , California State University Northridge , Northridge , California 91330 , United States
| | - Farbod Ebrahimi
- Inston, Inc. , Los Angeles , California 90095 , United States
| | - Guoqiang Yu
- Department of Electrical and Computer Engineering , University of California , Los Angeles , California 90095 , United States
| | - Nicholas Kioussis
- Department of Physics and Astronomy , California State University Northridge , Northridge , California 91330 , United States
| | - Weigang Wang
- Department of Physics , University of Arizona , Tucson , Arizona 85721 , United States
| | - Tadakatsu Ohkubo
- National Institute for Materials Science (NIMS) , 1-2-1 Sengen , Tsukuba 305-0047 , Japan
| | - Pedram Khalili Amiri
- Department of Electrical and Computer Engineering , University of California , Los Angeles , California 90095 , United States
| | - Kang L Wang
- Department of Electrical and Computer Engineering , University of California , Los Angeles , California 90095 , United States
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11
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Feng Y, Cheng Z, Wang X. Extremely Large Non-equilibrium Tunnel Magnetoresistance Ratio in CoRhMnGe Based Magnetic Tunnel Junction by Interface Modification. Front Chem 2019; 7:550. [PMID: 31508406 PMCID: PMC6718457 DOI: 10.3389/fchem.2019.00550] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Accepted: 07/19/2019] [Indexed: 11/29/2022] Open
Abstract
Equiatomic quaternary Heusler compounds (EQHCs) generally have the advantages of high Curie temperature, large spin polarization and long spin diffusion length, and they are regarded as one of the most promising candidates for spintronics devices. Herein, we report a theoretical investigation on an EQHC CoRhMnGe based magnetic tunnel junction (MTJ) with (i) MnGe-terminated interface and (ii) modified pure Mn terminated interface, i.e., MnMn-terminated interface. By employing first principle calculations combined with non-equilibrium Green's function, the local density of states (LDOS), transmission coefficient, spin-polarized current, tunnel magnetoresistance (TMR) ratio and spin injection efficiency (SIE) as a function of bias voltage are studied. It reveals that when the MTJ under equilibrium state, TMR ratio of MnGe-terminated structure is as high as 3,438%. When the MTJ is modified to MnMn-terminated interface, TMR ratio at equilibrium is enhanced to 2 × 105%, and spin filtering effects are also strengthened. When bias voltage is applied to the MTJ, the TMR ratio of the MnGe-terminated structure suffers a dramatic loss. While the modified MnMn-terminated structure could preserve a large TMR value of 1 × 105%, even bias voltage rises up to 0.1 V, showing a robust bias endurance. These excellent spin transport properties make the CoRhMnGe a promising candidate material for spintronics devices.
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Affiliation(s)
- Yu Feng
- Laboratory for Quantum Design of Functional Materials, School of Physics and Electronic Engineering, Jiangsu Normal University, Xuzhou, China
| | - Zhenxiang Cheng
- Institute for Superconducting and Electronic Materials, University of Wollongong, Wollongong, NSW, Australia
| | - Xiaotian Wang
- School of Physical Science and Technology, Southwest University, Chongqing, China
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12
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Yang B, Peng X, Huang C, Yin D, Xiang H, Fu T. Higher Strength and Ductility than Diamond: Nanotwinned Diamond/Cubic Boron Nitride Multilayer. ACS APPLIED MATERIALS & INTERFACES 2018; 10:42804-42811. [PMID: 30421601 DOI: 10.1021/acsami.8b13763] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Recently, the nanotwinned structure has attracted considerable attention because of unprecedented improvement in its mechanical properties, thermal stability, and other properties. Here, we introduce the nanotwinned structure between two superhard materials [diamond and cubic boron nitride (cBN)] and obtain a nanotwinned diamond/cBN multilayered material with ultrahigh strength and unprecedented ductility. Under continuous shear deformation, the stress and total energy in the material develop in a zigzag way because of atomic reconfiguration. Further research shows that atomic reconfiguration occurs preferentially in the cBN region, followed by that in the diamond region by partial slip, and finally occurs at the interface through alternate "exchange" of the positions of C and B atoms. This multilevel stress release model can account for the significant increase in the strain range and peak stress of nanotwinned materials. These results could provide available information for the design of superhard materials with multilevel resistance to plastic deformation.
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Hu L, Hu P, Chen Y, Lin Z, Qiu C. Synthesis and Gas-Sensing Property of Highly Self-assembled Tungsten Oxide Nanosheets. Front Chem 2018; 6:452. [PMID: 30345268 PMCID: PMC6183069 DOI: 10.3389/fchem.2018.00452] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2018] [Accepted: 09/12/2018] [Indexed: 11/25/2022] Open
Abstract
We report the synthesis of tungsten oxide (WO3) nanosheets using a simple yet efficient hydrothermal technique free of surfactantand template. The WO3 nano-sheets are self-assembled as well to form ordered one-dimensional chain nanostructure. A comprehensive microscopic characterization reveals that the nano-sheets have triangular and circular two different shape edges, dislocation and stacking faults are also observed, which should have implications for our understanding of catalytic activity of ceria. We also propose a growth mechanism for the nano-sheets. As a result of this unique morphology, this WO3 nano-sheets are found to show excellent gas-sensing properties which can use as promising sensor materials detecting ethanol with low concentration.
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Affiliation(s)
- Liangbin Hu
- School of Mechanical Engineering, University of South China, Hengyang, China
| | - Pengfei Hu
- School of Mechanical Engineering, University of South China, Hengyang, China
| | - Yong Chen
- School of Mechanical Engineering, University of South China, Hengyang, China
| | - Zehui Lin
- School of Mechanical Engineering, University of South China, Hengyang, China
| | - Changjun Qiu
- School of Mechanical Engineering, University of South China, Hengyang, China
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14
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Xie Z, Yang F, Xu X, Lin R, Chen L. Functionalization of α-In 2Se 3 Monolayer via Adsorption of Small Molecule for Gas Sensing. Front Chem 2018; 6:430. [PMID: 30320063 PMCID: PMC6169259 DOI: 10.3389/fchem.2018.00430] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2018] [Accepted: 08/30/2018] [Indexed: 11/21/2022] Open
Abstract
Based on first-principles calculations, the adsorption of NO and NO2 gas molecules on the α-In2Se3 monolayer have been studied. The adsorption configuration, adsorption energy, electronic structure and charge transfer properties are investigated. It is found that the charge transfer processes of NO and NO2 adsorbed on the surface of α-In2Se3 monolayer exhibit electron donor and acceptor characteristics, respectively. After the adsorption of the molecules, the α-In2Se3 monolayers have new states near the Fermi level induced by NO and NO2, which can trigger some new effects on the conducting and optical properties of the materials, with potential benefits to gas selectivity. The present work provides new valuable results and theoretical foundation for potential applications of the In2Se3-based gas sensor.
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Affiliation(s)
- Zhi Xie
- College of Mechanical and Electronic Engineering, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Fugui Yang
- School of Electronic Information Science, Fujian Jiangxia University, Fuzhou, China
| | - Xuee Xu
- College of Mechanical and Electronic Engineering, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Rui Lin
- College of Mechanical and Electronic Engineering, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Limin Chen
- College of Mechanical and Electronic Engineering, Fujian Agriculture and Forestry University, Fuzhou, China
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15
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Jin L, Chen W, Zhang Y. Application of Graphene Hybrid Materials in Fault Characteristic Gas Detection of Oil-Immersed Equipment. Front Chem 2018; 6:399. [PMID: 30255013 PMCID: PMC6141624 DOI: 10.3389/fchem.2018.00399] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Accepted: 08/20/2018] [Indexed: 11/13/2022] Open
Abstract
Graphene and its hybrid materials, due to their unique structures and properties, have attracted enormous attention for both fundamental and applied research in the gas sensing field. This review highlights the recent advances in the application of graphene-based gas sensors in fault characteristic gas detection of oil-immersed equipment, which can effectively achieve condition monitoring of the oil-immersed power equipment. In this review, the synthetic methods of graphene hybrid materials with noble metals, metal oxides and their combination are presented. Then, the basic sensing mechanisms of graphene hybrid materials and gas sensing properties of graphene hybrid materials sensors to hydrogen (H2), carbon monoxide (CO), carbon dioxide (CO2), methane (CH4), acetylene (C2H2), ethylene (C2H4), and ethane (C2H6), which are the fault characteristic gas in oil-immersed power equipment, are summarized. Finally, the future challenges and prospects of graphene hybrid materials gas sensors in this field are discussed.
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Affiliation(s)
- Lingfeng Jin
- State Key Laboratory of Power Transmission Equipment & System Security and New Technology, Chongqing University, Chongqing, China
- School of Electrical Engineering, Chongqing University, Chongqing, China
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA, United States
| | - Weigen Chen
- State Key Laboratory of Power Transmission Equipment & System Security and New Technology, Chongqing University, Chongqing, China
- School of Electrical Engineering, Chongqing University, Chongqing, China
| | - Ying Zhang
- School of Electrical and Computer Engineering, Georgia Institute of Technology, Atlanta, GA, United States
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16
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Wu Y, Yang Y, Zhao X, Tan Y, Liu Y, Wang Z, Ran F. A Novel Hierarchical Porous 3D Structured Vanadium Nitride/Carbon Membranes for High-performance Supercapacitor Negative Electrodes. NANO-MICRO LETTERS 2018; 10:63. [PMID: 30393711 PMCID: PMC6199110 DOI: 10.1007/s40820-018-0217-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2018] [Accepted: 06/28/2018] [Indexed: 05/26/2023]
Abstract
Transition-metal nitrides exhibit wide potential windows and good electrochemical performance, but usually experience imbalanced practical applications in the energy storage field due to aggregation, poor circulation stability, and complicated syntheses. In this study, a novel and simple multi-phase polymeric strategy was developed to fabricate hybrid vanadium nitride/carbon (VN/C) membranes for supercapacitor negative electrodes, in which VN nanoparticles were uniformly distributed in the hierarchical porous carbon 3D networks. The supercapacitor negative electrode based on VN/C membranes exhibited a high specific capacitance of 392.0 F g-1 at 0.5 A g-1 and an excellent rate capability with capacitance retention of 50.5% at 30 A g-1. For the asymmetric device fabricated using Ni(OH)2//VN/C membranes, a high energy density of 43.0 Wh kg-1 at a power density of 800 W kg-1 was observed. Moreover, the device also showed good cycling stability of 82.9% at a current density of 1.0 A g-1 after 8000 cycles. This work may throw a light on simply the fabrication of other high-performance transition-metal nitride-based supercapacitor or other energy storage devices.
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Affiliation(s)
- Yage Wu
- State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou University of Technology, Lanzhou, 730050, People's Republic of China
| | - Yunlong Yang
- State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou University of Technology, Lanzhou, 730050, People's Republic of China
| | - Xiaoning Zhao
- State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou University of Technology, Lanzhou, 730050, People's Republic of China
| | - Yongtao Tan
- State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou University of Technology, Lanzhou, 730050, People's Republic of China
| | - Ying Liu
- State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou University of Technology, Lanzhou, 730050, People's Republic of China
| | - Zhen Wang
- State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou University of Technology, Lanzhou, 730050, People's Republic of China
| | - Fen Ran
- State Key Laboratory of Advanced Processing and Recycling of Non-ferrous Metals, Lanzhou University of Technology, Lanzhou, 730050, People's Republic of China.
- School of Material Science and Engineering, Lanzhou University of Technology, Lanzhou, 730050, People's Republic of China.
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17
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Stability, Electronic Structure, and Dehydrogenation Properties of Pristine and Doped 2D MgH2 by the First Principles Study. METALS 2018. [DOI: 10.3390/met8070482] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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18
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Zhang X, Cai W, Zhang X, Wang Z, Li Z, Zhang Y, Cao K, Lei N, Kang W, Zhang Y, Yu H, Zhou Y, Zhao W. Skyrmions in Magnetic Tunnel Junctions. ACS APPLIED MATERIALS & INTERFACES 2018; 10:16887-16892. [PMID: 29682962 DOI: 10.1021/acsami.8b03812] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
In this work, we demonstrate that skyrmions can be nucleated in the free layer of a magnetic tunnel junction (MTJ) with Dzyaloshinskii-Moriya interactions (DMIs) by a spin-polarized current with the assistance of stray fields from the pinned layer. The size, stability, and number of created skyrmions can be tuned by either the DMI strength or the stray field distribution. The interaction between the stray field and the DMI effective field is discussed. A device with multilevel tunneling magnetoresistance is proposed, which could pave the ways for skyrmion-MTJ-based multibit storage and artificial neural network computation. Our results may facilitate the efficient nucleation and electrical detection of skyrmions.
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Affiliation(s)
- Xueying Zhang
- Fert Beijing Institute, BDBC, School of Electronic and Information Engineering , Beihang University , Beijing 100191 , China
- Beihang-Goertek Joint Microelectronics Institute, Qingdao Research Institute , Beihang University , Qingdao 266101 , China
| | - Wenlong Cai
- Fert Beijing Institute, BDBC, School of Electronic and Information Engineering , Beihang University , Beijing 100191 , China
| | - Xichao Zhang
- School of Science and Engineering , The Chinese University of Hong Kong , Shenzhen 518172 , China
| | - Zilu Wang
- Fert Beijing Institute, BDBC, School of Electronic and Information Engineering , Beihang University , Beijing 100191 , China
| | - Zhi Li
- Fert Beijing Institute, BDBC, School of Electronic and Information Engineering , Beihang University , Beijing 100191 , China
- Beihang-Goertek Joint Microelectronics Institute, Qingdao Research Institute , Beihang University , Qingdao 266101 , China
| | - Yu Zhang
- Fert Beijing Institute, BDBC, School of Electronic and Information Engineering , Beihang University , Beijing 100191 , China
| | - Kaihua Cao
- Fert Beijing Institute, BDBC, School of Electronic and Information Engineering , Beihang University , Beijing 100191 , China
| | - Na Lei
- Fert Beijing Institute, BDBC, School of Electronic and Information Engineering , Beihang University , Beijing 100191 , China
- Beihang-Goertek Joint Microelectronics Institute, Qingdao Research Institute , Beihang University , Qingdao 266101 , China
| | - Wang Kang
- Fert Beijing Institute, BDBC, School of Electronic and Information Engineering , Beihang University , Beijing 100191 , China
| | - Yue Zhang
- Fert Beijing Institute, BDBC, School of Electronic and Information Engineering , Beihang University , Beijing 100191 , China
| | - Haiming Yu
- Fert Beijing Institute, BDBC, School of Electronic and Information Engineering , Beihang University , Beijing 100191 , China
| | - Yan Zhou
- School of Science and Engineering , The Chinese University of Hong Kong , Shenzhen 518172 , China
| | - Weisheng Zhao
- Fert Beijing Institute, BDBC, School of Electronic and Information Engineering , Beihang University , Beijing 100191 , China
- Beihang-Goertek Joint Microelectronics Institute, Qingdao Research Institute , Beihang University , Qingdao 266101 , China
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19
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Ma X, Hu J. Large Perpendicular Magnetocrystalline Anisotropy at the Fe/Pb(001) Interface. ACS APPLIED MATERIALS & INTERFACES 2018; 10:13181-13186. [PMID: 29577724 DOI: 10.1021/acsami.8b00594] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The search for ultrathin magnetic films with large perpendicular magnetocrystalline anisotropy (PMA) has been inspired for years by the continuous miniaturization of magnetic units in spintronics devices. The common magnetic materials used in research and applications are based on Fe because the pure Fe metal is the best yet simple magnetic material from nature. Through systematic first-principles calculations, we explored the possibility to produce large PMA with ultrathin Fe on non-noble and non-magnetic Pb(001) substrate. Interestingly, huge magnetocrystalline anisotropy energy (MAE) of 7.6 meV was found in the Pb/Fe/Pb(001) sandwich structure with only half monolayer Fe. The analysis of electronic structures reveals that the magnetic proximity effect at the interface is responsible for this significant enhancement of MAE. The MAE further increases to 13.6 meV with triply repeated capping Pb and intermediate Fe layers. Furthermore, the MAE can be tuned conveniently by charge injection.
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20
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Bean JJ, Saito M, Fukami S, Sato H, Ikeda S, Ohno H, Ikuhara Y, McKenna KP. Atomic structure and electronic properties of MgO grain boundaries in tunnelling magnetoresistive devices. Sci Rep 2017; 7:45594. [PMID: 28374755 PMCID: PMC5379487 DOI: 10.1038/srep45594] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2017] [Accepted: 02/27/2017] [Indexed: 11/11/2022] Open
Abstract
Polycrystalline metal oxides find diverse applications in areas such as nanoelectronics, photovoltaics and catalysis. Although grain boundary defects are ubiquitous their structure and electronic properties are very poorly understood since it is extremely challenging to probe the structure of buried interfaces directly. In this paper we combine novel plan-view high-resolution transmission electron microscopy and first principles calculations to provide atomic level understanding of the structure and properties of grain boundaries in the barrier layer of a magnetic tunnel junction. We show that the highly [001] textured MgO films contain numerous tilt grain boundaries. First principles calculations reveal how these grain boundaries are associated with locally reduced band gaps (by up to 3 eV). Using a simple model we show how shunting a proportion of the tunnelling current through grain boundaries imposes limits on the maximum magnetoresistance that can be achieved in devices.
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Affiliation(s)
- Jonathan J. Bean
- Department of Physics, University of York, Heslington, York, North Yorkshire, YO10 5DD,UK
| | - Mitsuhiro Saito
- Institute of Engineering Innovation, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-8656, Japan
- Advanced Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
| | - Shunsuke Fukami
- Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
- Center for Spintronics Integrated Systems, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
- Center for Innovative Integrated Electronic Systems, Tohoku University, 468-1 Aramaki Aza Aoba, Aoba-ku, Sendai 980-0845, Japan
- Center for Spintronics Research Network, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
| | - Hideo Sato
- Center for Spintronics Integrated Systems, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
- Center for Innovative Integrated Electronic Systems, Tohoku University, 468-1 Aramaki Aza Aoba, Aoba-ku, Sendai 980-0845, Japan
- Center for Spintronics Research Network, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
| | - Shoji Ikeda
- Center for Spintronics Integrated Systems, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
- Center for Innovative Integrated Electronic Systems, Tohoku University, 468-1 Aramaki Aza Aoba, Aoba-ku, Sendai 980-0845, Japan
- Center for Spintronics Research Network, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
| | - Hideo Ohno
- Advanced Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
- Laboratory for Nanoelectronics and Spintronics, Research Institute of Electrical Communication, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
- Center for Spintronics Integrated Systems, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
- Center for Innovative Integrated Electronic Systems, Tohoku University, 468-1 Aramaki Aza Aoba, Aoba-ku, Sendai 980-0845, Japan
- Center for Spintronics Research Network, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
| | - Yuichi Ikuhara
- Institute of Engineering Innovation, The University of Tokyo, 2-11-16 Yayoi, Bunkyo-ku, Tokyo 113-8656, Japan
- Advanced Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577, Japan
| | - Keith P. McKenna
- Department of Physics, University of York, Heslington, York, North Yorkshire, YO10 5DD,UK
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