| Project/Area Number |
14205002
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| Research Category |
Grant-in-Aid for Scientific Research (A)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Applied materials science/Crystal engineering
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| Research Institution | Tohoku University |
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Principal Investigator |
OHNO Yuzo Tohoku University, Research Institute of Electrical Communication, Associate Professor, 電気通信研究所, 助教授 (00282012)
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| Co-Investigator(Kenkyū-buntansha) |
OHNO Hideo Tohoku University, Research Institute of Electrical Communication, Professor, 電気通信研究所, 教授 (00152215)
MATSUKURA Fumihiro Tohoku University, Research Institute of Electrical Communication, Research Associate, 電気通信研究所, 助手 (50261574)
OHTANI Keita Tohoku University, Research Institute of Electrical Communication, Research Associate, 電気通信研究所, 助手 (40333893)
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| Project Period (FY) |
2002 – 2004
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| Project Status |
Completed (Fiscal Year 2004)
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| Budget Amount *help |
¥42,380,000 (Direct Cost: ¥32,600,000、Indirect Cost: ¥9,780,000)
Fiscal Year 2004: ¥10,530,000 (Direct Cost: ¥8,100,000、Indirect Cost: ¥2,430,000)
Fiscal Year 2003: ¥13,650,000 (Direct Cost: ¥10,500,000、Indirect Cost: ¥3,150,000)
Fiscal Year 2002: ¥18,200,000 (Direct Cost: ¥14,000,000、Indirect Cost: ¥4,200,000)
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| Keywords | Spin coherence / magnetic semiconductors / carrier spin / nuclear spin / carrier-induced ferromagnetism / spin injection / nuclear magnetic resonance / ferromagnet |
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| Research Abstract |
The purpose of the research is to establish fundamental technology for spintronics devices in which information is born and processed by spins. Here, we designed and fabricated ferromagnetic/non-magnetic semiconductor quantum structures and investigated the unique optical, electrical, and magnetic properties in those structures by controlling the spin states of carriers, nuclei, excitons, and magnetic ions with electrical and optical means. The achievements of the research are summarized as :
1.We manifested that the efficiency of electrical electron spin injection in p-ferromagnetic/n^+-non-magnetic semiconductor tunnel junction sensitively depends on the thickness and doping concentration of n^+-GaAs interface layer by performing a systematic experiments, and showed the optimized condition.
2.We studied the effect of anisotropic g-factor and hyperfine interaction in n-GaAs/AlGaAs (110) quantum wells by time-resolved Faraday rotation technique. We observed bistability and hysteresis of dynamic nuclear polarization, which were well reproduced by self-consistent calculation. We also evaluated the degree of dynamic nuclear polarization to be 30%.
3.We demonstrated that the hyperfine interaction and dynamic nuclear polarization can be controlled by changing the background electron density with gate electric field in a gated n-GaAs/AlGaAs (110) quantum well. We showed that the experimental observation can be explained by metal-insulator transition, on which the hyperfine interaction depends sensitively.
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