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Liu X, Tang N, Fang C, Wan C, Zhang S, Zhang X, Guan H, Zhang Y, Qian X, Ji Y, Ge W, Han X, Shen B. Spin relaxation induced by interfacial effects in n-GaN/MgO/Co spin injectors. RSC Adv 2020; 10:12547-12553. [PMID: 35497583 PMCID: PMC9051297 DOI: 10.1039/d0ra00464b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2020] [Accepted: 03/19/2020] [Indexed: 11/21/2022] Open
Abstract
Spin relaxation, affected by interfacial effects, is a critical process for electrical spin injection and transport in semiconductor-based spintronics. In this work, the electrical spin injection into n-GaN via n-GaN/MgO/Co tunnel barrier was realized, and the interface-related spin relaxation was investigated by both electrical Hanle effect measurement and time-resolved Kerr rotation (TRKR) spectrum. It was found that the spin relaxation caused by interfacial random magnetostatic field was nearly equal to the intrinsic contributions at low temperature (less than 80 K) and could be suppressed by smoother n-GaN/Co interface. When the interfacial random magnetostatic field was suppressed, the spin relaxation time extracted from the electrical injection process was still shorter than that in bulk conduction band, which was attributed to Rashba spin-orbit coupling (SOC) induced by the interface band bending in the depletion region. Due to thermal activation, luckily, the spin relaxation induced by the interfacial Rashba SOC was suppressed at temperatures higher than 50 K. These results illustrate that (1) spin relaxation time could be as long as 300 ps for GaN and (2) the influences of interfacial effects could be engineered to further prolong spin relaxation time, both of which shed lights on GaN-based spintronic devices with direct and wide bandgap.
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Affiliation(s)
- Xingchen Liu
- State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University Beijing 100871 China
| | - Ning Tang
- State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University Beijing 100871 China .,Frontiers Science Center for Nano-optoelectronics & Collaboration Innovation Center of Quantum Matter, Peking University Beijing 100871 China
| | - Chi Fang
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, University of Chinese Academy of Sciences, Chinese Academy of Sciences Beijing 100190 China
| | - Caihua Wan
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, University of Chinese Academy of Sciences, Chinese Academy of Sciences Beijing 100190 China
| | - Shixiong Zhang
- State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University Beijing 100871 China
| | - Xiaoyue Zhang
- State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University Beijing 100871 China
| | - Hongming Guan
- State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University Beijing 100871 China
| | - Yunfan Zhang
- State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University Beijing 100871 China
| | - Xuan Qian
- State Key Laboratory for Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences Beijing 100083 China.,College of Materials Science and Opto-Electronic Technology, College of Physical Sciences, University of Chinese Academy of Sciences Beijing 100049 China
| | - Yang Ji
- State Key Laboratory for Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences Beijing 100083 China.,College of Materials Science and Opto-Electronic Technology, College of Physical Sciences, University of Chinese Academy of Sciences Beijing 100049 China
| | - Weikun Ge
- State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University Beijing 100871 China
| | - Xiufeng Han
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, University of Chinese Academy of Sciences, Chinese Academy of Sciences Beijing 100190 China
| | - Bo Shen
- State Key Laboratory of Artificial Microstructure and Mesoscopic Physics, School of Physics, Peking University Beijing 100871 China .,Frontiers Science Center for Nano-optoelectronics & Collaboration Innovation Center of Quantum Matter, Peking University Beijing 100871 China
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2
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Chen W, Luo K, Li L, Zilberberg O. Proposal for Detecting Nodal-Line Semimetal Surface States with Resonant Spin-Flipped Reflection. PHYSICAL REVIEW LETTERS 2018; 121:166802. [PMID: 30387652 DOI: 10.1103/physrevlett.121.166802] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/31/2018] [Revised: 05/23/2018] [Indexed: 06/08/2023]
Abstract
Topological nodal-line semimetals are predicted to exhibit unique drumheadlike surface states (DSSs). Yet, direct detection of such states remains a challenge. Here, we propose spin-resolved transport in a junction between a normal metal and a spin-orbit coupled nodal-line semimetal as the mechanism for their detection. Specifically, we find that in such an interface the DSSs induce resonant spin-flipped reflection. This effect can be probed by both vertical spin transport and lateral charge transport between antiparallel magnetic terminals. In the tunneling limit of the junction, both spin and charge conductances exhibit a resonant peak around zero energy, providing unique evidence of the DSSs. This signature is robust to both dispersive DSSs and interface disorder. Based on numerical calculations, we show that the scheme can be implemented in the topological semimetal HgCr_{2}Se_{4}.
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Affiliation(s)
- Wei Chen
- Institute for Theoretical Physics, ETH Zurich, 8093 Zürich, Switzerland
- College of Science, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
| | - Kun Luo
- College of Science, Nanjing University of Aeronautics and Astronautics, Nanjing 210016, China
| | - Lin Li
- College of Physics and Electronic Engineering, and Center for Computational Sciences, Sichuan Normal University, Chengdu 610068, China
- Shenzhen Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Oded Zilberberg
- Institute for Theoretical Physics, ETH Zurich, 8093 Zürich, Switzerland
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Chen JY, Ho CY, Lu ML, Chu LJ, Chen KC, Chu SW, Chen W, Mou CY, Chen YF. Efficient spin-light emitting diodes based on InGaN/GaN quantum disks at room temperature: a new self-polarized paradigm. NANO LETTERS 2014; 14:3130-3137. [PMID: 24807793 DOI: 10.1021/nl5003312] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
A well-behaved spin-light emitting diode (LED) composed of InGaN/GaN multiple quantum disks (MQDs), ferromagnetic contact, and Fe3O4 nanoparticles has been designed, fabricated, and characterized. The degree of circular polarization of electroluminescence (EL) can reach up to a high value of 10.9% at room temperature in a low magnetic field of 0.35 T, which overcomes a very low degree of spin polarization in nitride semiconductors due to the weak spin-orbit interaction. Several underlying mechanisms play significant roles simultaneously in this newly designed device for the achievement of such a high performance. Most of all, the vacancy between nanodisks can be filled by half-metal nanoparticles with suitable energy band alignment, which enables selective transfer of spin polarized electrons and holes and leads to the enhanced output spin polarization of LED. Unlike previously reported mechanisms, this new process leads to a weak dependence of spin relaxation on temperature. Additionally, the internal strain in planar InGaN/GaN multiple quantum wells can be relaxed in the nanodisk formation process, which leads to the disappearance of Rashba Hamiltonian and enhances the spin relaxation time. Our approach therefore opens up a new route for the further research and development of semiconductor spintronics.
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Affiliation(s)
- J Y Chen
- Department of Physics, National Taiwan University , Taipei 106, Taiwan
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4
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Jana S, Srivastava BB, Jana S, Bose R, Pradhan N. Multifunctional Doped Semiconductor Nanocrystals. J Phys Chem Lett 2012; 3:2535-2540. [PMID: 26295871 DOI: 10.1021/jz3010877] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Multifunctional nanomaterials with combined magnetic and optical properties remain one of the most demanded materials in upcoming research. To obtain these materials, we report here several doped semiconductor nanocrystals that simultaneously show tunable emission in a visible and NIR spectral window, above-room-temperature ferromagnetism, and improved conductivity. These nanocrystals are designed by inserting Ni(II) as a dopant in various semiconducting hosts with binary, alloyed, and ternary composition, and the induced multifunctional properties are observed to be stable and reproducible. These semiconducting materials combined with fluorescence and magnetic properties would be useful for a wide range of applications spanning from life science to modern developing device technology.
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Affiliation(s)
- Santanu Jana
- Department of Materials Science and Centre for Advance Materials, Indian Association for the Cultivation of Science, Jadavpur, Kolkata-700032
| | - Bhupendra B Srivastava
- Department of Materials Science and Centre for Advance Materials, Indian Association for the Cultivation of Science, Jadavpur, Kolkata-700032
| | - Somnath Jana
- Department of Materials Science and Centre for Advance Materials, Indian Association for the Cultivation of Science, Jadavpur, Kolkata-700032
| | - Riya Bose
- Department of Materials Science and Centre for Advance Materials, Indian Association for the Cultivation of Science, Jadavpur, Kolkata-700032
| | - Narayan Pradhan
- Department of Materials Science and Centre for Advance Materials, Indian Association for the Cultivation of Science, Jadavpur, Kolkata-700032
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5
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Chambers SA. Epitaxial growth and properties of doped transition metal and complex oxide films. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2010; 22:219-248. [PMID: 20217685 DOI: 10.1002/adma.200901867] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
The detailed science and technology of crystalline oxide film growth using vacuum methods is reviewed and discussed with an eye toward gaining fundamental insights into the relationships between growth process and parameters, film and interface structure and composition, and electronic, magnetic and photochemical properties. The topic is approached first from a comparative point of view based on the most widely used growth methods, and then on the basis of specific material systems that have generated very high levels of interest. Emphasis is placed on the wide diversity of structural, electronic, optical and magnetic properties exhibited by oxides, and the fascinating results that this diversity of properties can produce when combined with the degrees of freedom afforded by heteroepitaxy.
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Affiliation(s)
- Scott A Chambers
- Chemical and Materials Science Division, Fundamental and Computational Sciences Directorate, Pacific Northwest National Laboratory, PO Box 999, MS K8-87, Richland, WA 99352, USA.
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Zega TJ, Hanbicki AT, Erwin SC, Zutić I, Kioseoglou G, Li CH, Jonker BT, Stroud RM. Determination of interface atomic structure and its impact on spin transport using Z-contrast microscopy and density-functional theory. PHYSICAL REVIEW LETTERS 2006; 96:196101. [PMID: 16803113 DOI: 10.1103/physrevlett.96.196101] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2005] [Indexed: 05/10/2023]
Abstract
We combine Z-contrast scanning transmission electron microscopy with density-functional-theory calculations to determine the atomic structure of the interface in spin-polarized light-emitting diodes. A 44% increase in spin-injection efficiency occurs after a low-temperature anneal, which produces an ordered, coherent interface consisting of a single atomic plane of alternating Fe and As atoms. First-principles transport calculations indicate that the increase in spin-injection efficiency is due to the abruptness and coherency of the annealed interface.
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Affiliation(s)
- Thomas J Zega
- Naval Research Laboratory, Washington, DC 20375, USA
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Kaspar TC, Heald SM, Wang CM, Bryan JD, Droubay T, Shutthanandan V, Thevuthasan S, McCready DE, Kellock AJ, Gamelin DR, Chambers SA. Negligible magnetism in excellent structural quality Cr(x)Ti(1-x)O(2) anatase: contrast with high-T(C) ferromagnetism in structurally defective Cr(x)Ti(1-x)O(2). PHYSICAL REVIEW LETTERS 2005; 95:217203. [PMID: 16384176 DOI: 10.1103/physrevlett.95.217203] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/01/2005] [Indexed: 05/05/2023]
Abstract
We reexamine the mechanism of ferromagnetism in doped TiO(2) anatase, using epitaxial Cr:TiO(2) with excellent structural quality as a model system. In contrast to highly oriented but defective Cr:TiO(2) (approximately 0.5 micro(b)/Cr), these structurally superior single crystal films exhibit negligible ferromagnetism. Similar results were obtained for Co:TiO(2). We show for the first time that charge-compensating oxygen vacancies alone, as predicted by F-center mediated exchange, are not sufficient to activate ferromagnetism. Instead, the onset of ferromagnetism correlates with the presence of structural defects.
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Affiliation(s)
- T C Kaspar
- Pacific Northwest National Laboratory, Richland, Washington 99352, USA
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8
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Effects of doping profile and post-growth annealing on spin injection from Fe into (Al,Ga)As heterostructures. ACTA ACUST UNITED AC 2005. [DOI: 10.1116/1.1949214] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
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Kioseoglou G, Hanbicki AT, Sullivan JM, van 't Erve OMJ, Li CH, Erwin SC, Mallory R, Yasar M, Petrou A, Jonker BT. Electrical spin injection from an n-type ferromagnetic semiconductor into a III-V device heterostructure. NATURE MATERIALS 2004; 3:799-803. [PMID: 15502834 DOI: 10.1038/nmat1239] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2004] [Accepted: 08/23/2004] [Indexed: 05/24/2023]
Abstract
The use of carrier spin in semiconductors is a promising route towards new device functionality and performance. Ferromagnetic semiconductors (FMSs) are promising materials in this effort. An n-type FMS that can be epitaxially grown on a common device substrate is especially attractive. Here, we report electrical injection of spin-polarized electrons from an n-type FMS, CdCr(2)Se(4), into an AlGaAs/GaAs-based light-emitting diode structure. An analysis of the electroluminescence polarization based on quantum selection rules provides a direct measure of the sign and magnitude of the injected electron spin polarization. The sign reflects minority rather than majority spin injection, consistent with our density-functional-theory calculations of the CdCr(2)Se(4) conduction-band edge. This approach confirms the exchange-split band structure and spin-polarized carrier population of an FMS, and demonstrates a litmus test for these FMS hallmarks that discriminates against spurious contributions from magnetic precipitates.
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Affiliation(s)
- George Kioseoglou
- Materials Science and Technology Division, Naval Research Laboratory, 4555 Overlook Avenue SW, Washington, DC 20375, USA
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