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Wu Q, Liu Y, Wang H, Li Y, Huang W, Zhao J, Chen Y. Observation of spin-polarized photoconductivity in (Ga,Mn)As/GaAs heterojunction without magnetic field. Sci Rep 2017; 7:40558. [PMID: 28084437 PMCID: PMC5233956 DOI: 10.1038/srep40558] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 12/08/2016] [Indexed: 11/09/2022] Open
Abstract
In the absent of magnetic field, we have observed the anisotropic spin polarization degree of photoconduction (SPD-PC) in (Ga,Mn)As/GaAs heterojunction. We think three kinds of mechanisms contribute to the magnetic related signal, (i) (Ga,Mn)As self-producing due to the valence band polarization, (ii) unequal intensity of left and right circularly polarized light reaching to GaAs layer to excite unequal spin polarized carriers in GaAs layer, and (iii) (Ga,Mn)As as the spin filter layer for spin transport from GaAs to (Ga,Mn)As. Different from the previous experiments, the influence coming from the Zeeman splitting induced by an external magnetic field can be avoided here. While temperature dependence experiment indicates that the SPD-PC is mixed with the magnetic uncorrelated signals, which may come from current induced spin polarization.
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Affiliation(s)
- Qing Wu
- Key Laboratory of Semiconductor Materials Science, Beijing Key Laboratory of Low Dimensional Semiconductor Materials and Devices, Institute of Semiconductors, Chinese Academy of Sciences, and University of Chinese Academy of Sciences, Beijing, 100083, China
| | - Yu Liu
- Key Laboratory of Semiconductor Materials Science, Beijing Key Laboratory of Low Dimensional Semiconductor Materials and Devices, Institute of Semiconductors, Chinese Academy of Sciences, and University of Chinese Academy of Sciences, Beijing, 100083, China
| | - Hailong Wang
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, and University of Chinese Academy of Sciences, Beijing, 100083, China
| | - Yuan Li
- Key Laboratory of Semiconductor Materials Science, Beijing Key Laboratory of Low Dimensional Semiconductor Materials and Devices, Institute of Semiconductors, Chinese Academy of Sciences, and University of Chinese Academy of Sciences, Beijing, 100083, China
| | - Wei Huang
- Key Laboratory of Semiconductor Materials Science, Beijing Key Laboratory of Low Dimensional Semiconductor Materials and Devices, Institute of Semiconductors, Chinese Academy of Sciences, and University of Chinese Academy of Sciences, Beijing, 100083, China
| | - Jianhua Zhao
- State Key Laboratory of Superlattices and Microstructures, Institute of Semiconductors, Chinese Academy of Sciences, and University of Chinese Academy of Sciences, Beijing, 100083, China
| | - Yonghai Chen
- Key Laboratory of Semiconductor Materials Science, Beijing Key Laboratory of Low Dimensional Semiconductor Materials and Devices, Institute of Semiconductors, Chinese Academy of Sciences, and University of Chinese Academy of Sciences, Beijing, 100083, China
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Green RJ, Regier TZ, Leedahl B, McLeod JA, Xu XH, Chang GS, Kurmaev EZ, Moewes A. Adjacent Fe-Vacancy Interactions as the Origin of Room Temperature Ferromagnetism in (In(1-x)Fe(x))2O3. PHYSICAL REVIEW LETTERS 2015; 115:167401. [PMID: 26550901 DOI: 10.1103/physrevlett.115.167401] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Indexed: 06/05/2023]
Abstract
Dilute magnetic semiconductors (DMSs) show great promise for applications in spin-based electronics, but in most cases continue to elude explanations of their magnetic behavior. Here, we combine quantitative x-ray spectroscopy and Anderson impurity model calculations to study ferromagnetic Fe-substituted In2O3 films, and we identify a subset of Fe atoms adjacent to oxygen vacancies in the crystal lattice which are responsible for the observed room temperature ferromagnetism. Using resonant inelastic x-ray scattering, we map out the near gap electronic structure and provide further support for this conclusion. Serving as a concrete verification of recent theoretical results and indirect experimental evidence, these results solidify the role of impurity-vacancy coupling in oxide-based DMSs.
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Affiliation(s)
- R J Green
- Department of Physics & Engineering Physics, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2, Canada
| | - T Z Regier
- Canadian Light Source, University of Saskatchewan, Saskatoon, Saskatchewan S7N 0X4, Canada
| | - B Leedahl
- Department of Physics & Engineering Physics, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2, Canada
| | - J A McLeod
- Department of Physics & Engineering Physics, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2, Canada
| | - X H Xu
- School of Chemistry & Materials Science, Shanxi Normal University, Linfen 041004, People's Republic of China
| | - G S Chang
- Department of Physics & Engineering Physics, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2, Canada
| | - E Z Kurmaev
- M. N. Mikheev Institute of Metal Physics of the Ural Branch of Russian Academy of Sciences, 620990 Yekaterinburg, Russia
- Ural Federal University, 19 Mira Street, 620002 Yekaterinburg, Russia
| | - A Moewes
- Department of Physics & Engineering Physics, University of Saskatchewan, Saskatoon, Saskatchewan S7N 5E2, Canada
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Webber D, de Boer T, Yildirim M, March S, Mathew R, Gamouras A, Liu X, Dobrowolska M, Furdyna J, Hall K. Measurement of coherence decay in GaMnAs using femtosecond four-wave mixing. J Vis Exp 2013:51094. [PMID: 24326982 PMCID: PMC4028863 DOI: 10.3791/51094] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The application of femtosecond four-wave mixing to the study of fundamental properties of diluted magnetic semiconductors ((s,p)-d hybridization, spin-flip scattering) is described, using experiments on GaMnAs as a prototype III-Mn-V system. Spectrally-resolved and time-resolved experimental configurations are described, including the use of zero-background autocorrelation techniques for pulse optimization. The etching process used to prepare GaMnAs samples for four-wave mixing experiments is also highlighted. The high temporal resolution of this technique, afforded by the use of short (20 fsec) optical pulses, permits the rapid spin-flip scattering process in this system to be studied directly in the time domain, providing new insight into the strong exchange coupling responsible for carrier-mediated ferromagnetism. We also show that spectral resolution of the four-wave mixing signal allows one to extract clear signatures of (s,p)-d hybridization in this system, unlike linear spectroscopy techniques. This increased sensitivity is due to the nonlinearity of the technique, which suppresses defect-related contributions to the optical response. This method may be used to measure the time scale for coherence decay (tied to the fastest scattering processes) in a wide variety of semiconductor systems of interest for next generation electronics and optoelectronics.
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Affiliation(s)
- Daniel Webber
- Department of Physics and Atmospheric Science, Dalhousie University
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Dobrowolska M, Tivakornsasithorn K, Liu X, Furdyna JK, Berciu M, Yu KM, Walukiewicz W. Controlling the Curie temperature in (Ga,Mn)As through location of the Fermi level within the impurity band. NATURE MATERIALS 2012; 11:444-449. [PMID: 22344325 DOI: 10.1038/nmat3250] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2011] [Accepted: 01/18/2012] [Indexed: 05/31/2023]
Abstract
The ferromagnetic semiconductor (Ga,Mn)As has emerged as the most studied material for prototype applications in semiconductor spintronics. Because ferromagnetism in (Ga,Mn)As is hole-mediated, the nature of the hole states has direct and crucial bearing on its Curie temperature T(C). It is vigorously debated, however, whether holes in (Ga,Mn)As reside in the valence band or in an impurity band. Here we combine results of channelling experiments, which measure the concentrations both of Mn ions and of holes relevant to the ferromagnetic order, with magnetization, transport, and magneto-optical data to address this issue. Taken together, these measurements provide strong evidence that it is the location of the Fermi level within the impurity band that determines T(C) through determining the degree of hole localization. This finding differs drastically from the often accepted view that T(C) is controlled by valence band holes, thus opening new avenues for achieving higher values of T(C).
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Affiliation(s)
- M Dobrowolska
- Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556, USA.
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