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Liu Q, Lin X, Zhu L. Absence of Spin-Orbit Torque and Discovery of Anisotropic Planar Nernst Effect in CoFe Single Crystal. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2023; 10:e2301409. [PMID: 37485640 PMCID: PMC10520638 DOI: 10.1002/advs.202301409] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Revised: 06/29/2023] [Indexed: 07/25/2023]
Abstract
Exploration of exotic spin polarizations in single crystals is of increasing interest. A current of longitudinal spins, the so-called "Dresselhaus-like" spin current, which is forbidden in materials lacking certain inversion asymmetries, is implied to be generated by a charge current at the interface of single-crystal CoFe. This work reports unambiguous evidence that there is no indication of spin current of any spin polarizations from the interface or bulk of single-crystalline CoFe and that the sin2φ second harmonic Hall voltage, which is previously assumed to signify Dresselhaus-like spin current, is not related to any spin currents but rather a planar Nernst voltage induced by a longitudinal temperature gradient within the sample. Such sin2φ signal is independent of large applied magnetic fields and interfacial spin-orbit coupling, inversely correlated to the heat capacity of the substrates and overlayers, quadratic in charge current, and appears also in polycrystalline ferromagnets. Strikingly, the planar Nernst effect (PNE) in the CoFe single crystal has a strong fourfold anisotropy and varies with the crystalline orientation. Such strong, anisotropic PNE has widespread impacts on the analyses of a variety of spintronic experiments and opens a new avenue for the development of PNE-based thermoelectric battery and sensor applications.
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Affiliation(s)
- Qianbiao Liu
- State Key Laboratory for Superlattices and MicrostructuresInstitute of SemiconductorsChinese Academy of SciencesBeijing100083China
| | - Xin Lin
- State Key Laboratory for Superlattices and MicrostructuresInstitute of SemiconductorsChinese Academy of SciencesBeijing100083China
- College of Materials Science and Opto‐Electronic TechnologyUniversity of Chinese Academy of SciencesBeijing100049China
| | - Lijun Zhu
- State Key Laboratory for Superlattices and MicrostructuresInstitute of SemiconductorsChinese Academy of SciencesBeijing100083China
- College of Materials Science and Opto‐Electronic TechnologyUniversity of Chinese Academy of SciencesBeijing100049China
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2
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Liu S, Li Z, Yang K, Zhang E, Narayan A, Zhang X, Zhu J, Liu W, Liao Z, Kudo M, Toriyama T, Yang Y, Li Q, Ai L, Huang C, Sun J, Guo X, Bao W, Deng Q, Chen Y, Yin L, Shen J, Han X, Matsumura S, Zou J, Xu Y, Xu X, Wu H, Xiu F. Tuning 2D magnetism in Fe3+XGeTe2 films by element doping. Natl Sci Rev 2021; 9:nwab117. [PMID: 35822066 PMCID: PMC9270067 DOI: 10.1093/nsr/nwab117] [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: 08/20/2020] [Revised: 02/24/2021] [Accepted: 06/10/2021] [Indexed: 11/23/2022] Open
Abstract
Two-dimensional (2D) ferromagnetic materials have been discovered with tunable magnetism and orbital-driven nodal-line features. Controlling the 2D magnetism in exfoliated nanoflakes via electric/magnetic fields enables a boosted Curie temperature (TC) or phase transitions. One of the challenges, however, is the realization of high TC 2D magnets that are tunable, robust and suitable for large scale fabrication. Here, we report molecular-beam epitaxy growth of wafer-scale Fe3+XGeTe2 films with TC above room temperature. By controlling the Fe composition in Fe3+XGeTe2, a continuously modulated TC in a broad range of 185–320 K has been achieved. This widely tunable TC is attributed to the doped interlayer Fe that provides a 40% enhancement around the optimal composition X = 2. We further fabricated magnetic tunneling junction device arrays that exhibit clear tunneling signals. Our results show an effective and reliable approach, i.e. element doping, to producing robust and tunable ferromagnetism beyond room temperature in a large-scale 2D Fe3+XGeTe2 fashion.
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Affiliation(s)
- Shanshan Liu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
| | - Zihan Li
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
| | - Ke Yang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Laboratory for Computational Physical Sciences (MOE), Fudan University, Shanghai 200433, China
| | - Enze Zhang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
| | - Awadhesh Narayan
- Solid State and Structural Chemistry Unit, Indian Institute of Science, Bangalore 560012, India
| | - Xiaoqian Zhang
- School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China
| | - Jiayi Zhu
- Department of Physics, University of Washington, Seattle, WA 98195-1560, USA
| | - Wenqing Liu
- Department of Electronic Engineering, Royal Holloway University of London, Egham TW20 0EX, UK
| | - Zhiming Liao
- Materials Engineering, The University of Queensland, Brisbane QLD 4072, Australia
- Beijing Key Lab of Microstructure and Property of Advanced Material, Institute of Microstructure and Properties of Advanced Materials, Beijing University of Technology, Beijing 100124, China
| | - Masaki Kudo
- The Ultramicroscopy Research Center, Kyushu University, Fukuoka 819-0395, Japan
| | - Takaaki Toriyama
- The Ultramicroscopy Research Center, Kyushu University, Fukuoka 819-0395, Japan
| | - Yunkun Yang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
| | - Qiang Li
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
| | - Linfeng Ai
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
| | - Ce Huang
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
| | - Jiabao Sun
- Department of Electronic Engineering, Royal Holloway University of London, Egham TW20 0EX, UK
| | - Xiaojiao Guo
- State Key Laboratory of ASIC and System, School of Microelectronics, Fudan University, Shanghai 200433, China
| | - Wenzhong Bao
- State Key Laboratory of ASIC and System, School of Microelectronics, Fudan University, Shanghai 200433, China
| | - Qingsong Deng
- Beijing Key Lab of Microstructure and Property of Advanced Material, Institute of Microstructure and Properties of Advanced Materials, Beijing University of Technology, Beijing 100124, China
| | - Yanhui Chen
- Beijing Key Lab of Microstructure and Property of Advanced Material, Institute of Microstructure and Properties of Advanced Materials, Beijing University of Technology, Beijing 100124, China
| | - Lifeng Yin
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
| | - Jian Shen
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
| | - Xiaodong Han
- Beijing Key Lab of Microstructure and Property of Advanced Material, Institute of Microstructure and Properties of Advanced Materials, Beijing University of Technology, Beijing 100124, China
| | - Syo Matsumura
- The Ultramicroscopy Research Center, Kyushu University, Fukuoka 819-0395, Japan
- Department of Applied Quantum Physics and Nuclear Engineering, Kyushu University, Fukuoka 819-0395, Japan
| | - Jin Zou
- Materials Engineering, The University of Queensland, Brisbane QLD 4072, Australia
- Centre for Microscopy and Microanalysis, The University of Queensland, Brisbane QLD 4072, Australia
| | - Yongbing Xu
- School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China
| | - Xiaodong Xu
- Department of Physics, University of Washington, Seattle, WA 98195-1560, USA
| | - Hua Wu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Laboratory for Computational Physical Sciences (MOE), Fudan University, Shanghai 200433, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
| | - Faxian Xiu
- State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China
- Institute for Nanoelectronic Devices and Quantum Computing, Fudan University, Shanghai 200433, China
- Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, China
- Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
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3
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Tu HQ, Liu B, Huang DW, Ruan XZ, You B, Huang ZC, Zhai Y, Gao Y, Wang J, Wei LJ, Yuan Y, Xu YB, Du J. Gilbert damping in CoFeB/GaAs(001) film with enhanced in-plane uniaxial magnetic anisotropy. Sci Rep 2017; 7:43971. [PMID: 28262841 PMCID: PMC5338288 DOI: 10.1038/srep43971] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2016] [Accepted: 01/31/2017] [Indexed: 11/09/2022] Open
Abstract
A 3.5 nm amorphous CoFeB film was sputtered on GaAs (001) wafer substrate without applying magnetic field during deposition, and a significant in-plane uniaxial magnetic anisotropy (UMA) field (Hu) of about 300 Oe could be achieved. To precisely determine the intrinsic Gilbert damping constant (α) of this film, both ferromagnetic resonance (FMR) and time-resolved magneto-optical Kerr effect (TRMOKE) techniques were utilized. With good fitting of the dynamic spectra of FMR and TRMOKE, α is calculated to be 0.010 and 0.013, respectively. Obviously, the latter is 30% larger than the former, which is due to the transient heating effect during the TRMOKE measurement. In comparison with ordinary amorphous CoFeB films with negligible magnetic anisotropies, α is enhanced significantly in the CoFeB/GaAs(001) film, which may be mainly resulted from the enhanced spin-orbit coupling induced by the CoFeB/GaAs interface. However, the significant in-plane UMA plays minor role in the enhancement of α.
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Affiliation(s)
- H Q Tu
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, P. R. China.,Department of Mathematics and Physics, Nanjing Institute of Technology, Nanjing 211167, P. R. China
| | - B Liu
- School of Electronic Science and Engineering, Nanjing University, Nanjing 210046, P. R. China
| | - D W Huang
- School of Electronic Science and Engineering, Nanjing University, Nanjing 210046, P. R. China
| | - X Z Ruan
- School of Electronic Science and Engineering, Nanjing University, Nanjing 210046, P. R. China
| | - B You
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, P. R. China.,Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, P. R. China
| | - Z C Huang
- Department of Physics and Jiangsu Key Laboratory of Advanced Metallic Materials, Southeast University, Nanjing 211189, P. R. China
| | - Y Zhai
- Department of Physics and Jiangsu Key Laboratory of Advanced Metallic Materials, Southeast University, Nanjing 211189, P. R. China
| | - Y Gao
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, P. R. China
| | - J Wang
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, P. R. China
| | - L J Wei
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, P. R. China
| | - Y Yuan
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, P. R. China
| | - Y B Xu
- School of Electronic Science and Engineering, Nanjing University, Nanjing 210046, P. R. China
| | - J Du
- National Laboratory of Solid State Microstructures and Department of Physics, Nanjing University, Nanjing 210093, P. R. China.,Collaborative Innovation Center of Advanced Microstructures, Nanjing 210093, P. R. China
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4
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Spin-Dependent Transport in Fe/GaAs(100)/Fe Vertical Spin-Valves. Sci Rep 2016; 6:29845. [PMID: 27432047 PMCID: PMC4949422 DOI: 10.1038/srep29845] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2016] [Accepted: 06/21/2016] [Indexed: 12/14/2022] Open
Abstract
The integration of magnetic materials with semiconductors will lead to the development of the next spintronics devices such as spin field effect transistor (SFET), which is capable of both data storage and processing. While the fabrication and transport studies of lateral SFET have attracted greatly attentions, there are only few studies of vertical devices, which may offer the opportunity for the future three-dimensional integration. Here, we provide evidence of two-terminal electrical spin injection and detection in Fe/GaAs/Fe vertical spin-valves (SVs) with the GaAs layer of 50 nanometers thick and top and bottom Fe electrodes deposited by molecular beam epitaxy. The spin-valve effect, which corresponds to the individual switching of the top and bottom Fe layers, is bias dependent and observed up to 20 K. We propose that the strongly bias- and temperature-dependent MR is associated with spin transport at the interfacial Fe/GaAs Schottky contacts and in the GaAs membranes, where balance between the barrier profiles as well as the dwell time to spin lifetime ratio are crucial factors for determining the device operations. The demonstration of the fabrication and spin injection in the vertical SV with a semiconductor interlayer is expected to open a new avenue in exploring the SFET.
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5
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Liu W, Zhou Q, Chen Q, Niu D, Zhou Y, Xu Y, Zhang R, Wang J, van der Laan G. Probing the Buried Magnetic Interfaces. ACS APPLIED MATERIALS & INTERFACES 2016; 8:5752-5757. [PMID: 26887429 DOI: 10.1021/acsami.5b11438] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
Understanding magnetism in ferromagnetic metal/semiconductor (FM/SC) heterostructures is important to the development of the new-generation spin field-effect transistor. Here, we report an element-specific X-ray magnetic circular dichroism study of the interfacial magnetic moments for two FM/SC model systems, namely, Co/GaAs and Ni/GaAs, which was enabled using a specially designed FM1/FM2/SC superstructure. We observed a robust room temperature magnetization of the interfacial Co, while that of the interfacial Ni was strongly diminished down to 5 K because of hybridization of the Ni d(eg) and GaAs sp(3) states. The validity of the selected method was confirmed by first-principles calculations, showing only small deviations (<0.02 and <0.07 μB/atom for Co/GaAs and Ni/GaAs, respectively) compared to the real FM/SC interfaces. Our work proved that the electronic structure and magnetic ground state of the interfacial FM2 is not altered when the topmost FM2 is replaced by FM1 and that this model is applicable generally for probing the buried magnetic interfaces in the advanced spintronic materials..
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Affiliation(s)
- Wenqing Liu
- York-Nanjing Joint Center for Spintronics and Nanoengineering, School of Electronics Science and Engineering, Nanjing University , Nanjing 210093, China
- Spintronics and Nanodevice Laboratory, Department of Electronics, University of York , York YO10 5DD, U.K
- Department of Physics, The University of Hong Kong , Pokfulam, Hong Kong
| | - Qionghua Zhou
- Department of Physics, Southeast University , Nanjing 211189, China
| | - Qian Chen
- Department of Physics, Southeast University , Nanjing 211189, China
| | - Daxin Niu
- Spintronics and Nanodevice Laboratory, Department of Electronics, University of York , York YO10 5DD, U.K
| | - Yan Zhou
- York-Nanjing Joint Center for Spintronics and Nanoengineering, School of Electronics Science and Engineering, Nanjing University , Nanjing 210093, China
- Department of Physics, The University of Hong Kong , Pokfulam, Hong Kong
| | - Yongbing Xu
- York-Nanjing Joint Center for Spintronics and Nanoengineering, School of Electronics Science and Engineering, Nanjing University , Nanjing 210093, China
- Spintronics and Nanodevice Laboratory, Department of Electronics, University of York , York YO10 5DD, U.K
| | - Rong Zhang
- York-Nanjing Joint Center for Spintronics and Nanoengineering, School of Electronics Science and Engineering, Nanjing University , Nanjing 210093, China
| | - Jinlan Wang
- Department of Physics, Southeast University , Nanjing 211189, China
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6
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Liu WQ, Wang WY, Wang JJ, Wang FQ, Lu C, Jin F, Zhang A, Zhang QM, Laan GVD, Xu YB, Li QX, Zhang R. Atomic-Scale Interfacial Magnetism in Fe/Graphene Heterojunction. Sci Rep 2015; 5:11911. [PMID: 26145155 PMCID: PMC4491707 DOI: 10.1038/srep11911] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Accepted: 05/15/2015] [Indexed: 11/16/2022] Open
Abstract
Successful spin injection into graphene makes it a competitive contender in the race to become a key material for quantum computation, or the spin-operation-based data processing and sensing. Engineering ferromagnetic metal (FM)/graphene heterojunctions is one of the most promising avenues to realise it, however, their interface magnetism remains an open question up to this day. In any proposed FM/graphene spintronic devices, the best opportunity for spin transport could only be achieved where no magnetic dead layer exists at the FM/graphene interface. Here we present a comprehensive study of the epitaxial Fe/graphene interface by means of X-ray magnetic circular dichroism (XMCD) and density functional theory (DFT) calculations. The experiment has been performed using a specially designed FM1/FM2/graphene structure that to a large extent restores the realistic case of the proposed graphene-based transistors. We have quantitatively observed a reduced but still sizable magnetic moments of the epitaxial Fe ML on graphene, which is well resembled by simulations and can be attributed to the strong hybridization between the Fe 3dz2 and the C 2pz orbitals and the sp-orbital-like behavior of the Fe 3d electrons due to the presence of graphene.
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Affiliation(s)
- W Q Liu
- York-Nanjing Joint Centre (YNJC) for Spintronics and Nanoengineering, School of Electronics Science and Engineering, Nanjing University, Nanjing 210093, China.,Spintronics and Nanodevice Laboratory, Department of Electronics, University of York, York YO10 5DD, UK
| | - W Y Wang
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, China.,Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - J J Wang
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, China.,Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - F Q Wang
- York-Nanjing Joint Centre (YNJC) for Spintronics and Nanoengineering, School of Electronics Science and Engineering, Nanjing University, Nanjing 210093, China
| | - C Lu
- Spintronics and Nanodevice Laboratory, Department of Electronics, University of York, York YO10 5DD, UK
| | - F Jin
- Department of Physics, Renmin University of China, Beijing 100872, China
| | - A Zhang
- Department of Physics, Renmin University of China, Beijing 100872, China
| | - Q M Zhang
- Department of Physics, Renmin University of China, Beijing 100872, China
| | | | - Y B Xu
- York-Nanjing Joint Centre (YNJC) for Spintronics and Nanoengineering, School of Electronics Science and Engineering, Nanjing University, Nanjing 210093, China.,Spintronics and Nanodevice Laboratory, Department of Electronics, University of York, York YO10 5DD, UK
| | - Q X Li
- Hefei National Laboratory for Physical Sciences at the Microscale, University of Science and Technology of China, Hefei 230026, China.,Synergetic Innovation Center of Quantum Information and Quantum Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
| | - R Zhang
- York-Nanjing Joint Centre (YNJC) for Spintronics and Nanoengineering, School of Electronics Science and Engineering, Nanjing University, Nanjing 210093, China
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Tian CS, Qian D, Wu D, He RH, Wu YZ, Tang WX, Yin LF, Shi YS, Dong GS, Jin XF, Jiang XM, Liu FQ, Qian HJ, Sun K, Wang LM, Rossi G, Qiu ZQ, Shi J. Body-centered-cubic Ni and its magnetic properties. PHYSICAL REVIEW LETTERS 2005; 94:137210. [PMID: 15904031 DOI: 10.1103/physrevlett.94.137210] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2004] [Indexed: 05/02/2023]
Abstract
The body-centered-cubic (bcc) phase of Ni, which does not exist in nature, has been achieved as a thin film on GaAs(001) at 170 K via molecular beam epitaxy. The bcc Ni is ferromagnetic with a Curie temperature of 456 K and possesses a magnetic moment of 0.52+/-0.08 micro(B)/atom. The cubic magnetocrystalline anisotropy of bcc Ni is determined to be +4.0x10(5) ergs x cm(-3), as opposed to -5.7x10(4) ergs x cm(-3) for the naturally occurring face-centered-cubic (fcc) Ni. This sharp contrast in the magnetic anisotropy is attributed to the different electronic band structures between bcc Ni and fcc Ni, which are determined using angle-resolved photoemission with synchrotron radiation.
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Affiliation(s)
- C S Tian
- Surface Physics Laboratory, Fudan University, Shanghai 200433, China
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