| Project/Area Number |
14540311
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
固体物性Ⅰ(光物性・半導体・誘電体)
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| Research Institution | KANAGAWA INSTITUTE OF TECHNOLOGY |
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Principal Investigator |
TAKAHASHI Masao KANAGAWA INSTITUTE OF TECHNOLOGY, FACULTY OF TECHNOLOGY, PROFESSOR, 工学部, 教授 (00163288)
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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 |
¥3,100,000 (Direct Cost: ¥3,100,000)
Fiscal Year 2004: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 2003: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 2002: ¥1,900,000 (Direct Cost: ¥1,900,000)
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| Keywords | MAGNETIC SEMICONDUCTOR / SPINTORONICS / DILUTED MAGNETIC SEMICONDUCTOR / CARRIER INDUCED FERROMAGNETISM / EXCHANGE INTERACTION / 動的CPA / 光誘起相転移 / GaMnAs / コヒーレント・ポテンシャル近似(CPA) / (Ga,Mn)As |
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| Research Abstract |
Applying the dynamical coherent potential approximation to a simple model, we have systematically studied the carrier states in A_<1-x>Mn_xB-type diluted magnetic semiconductors (DMS's). The model calculation was performed for three typical cases of DMS's : The cases with strong and moderate exchange interactions in the absence of nonmagnetic potentials, and the case with strong attractive nonmagnetic potentials in addition to moderate exchange interaction. When the exchange interaction is sufficiently strong, magnetic impurity bands split from the host band. Carriers in the magnetic impurity band mainly stay at magnetic sites, and coupling between the carrier spin and the localized spin is very strong. The hopping of the carriers among the magnetic sites causes ferromagnetism through a double-exchange (DE)-like mechanism. We have investigated the condition for the DE-like mechanism to operate in DMS's. The result reveals that the nonmagnetic attractive potential at the magnetic site assists the formation of the magnetic impurity band and makes the DE-like mechanism operative by substantially enhancing the effect of the exchange interaction. Using conventional parameters we have studied the carrier states in Ga_<1-x>Mn_xAs. The result shows that the ferromagnetism is caused through the DE-like mechanism by the carriers in the bandtail originating from the impurity states.
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