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Mechanism of carrier-induced ferromagnetism in magnetic semiconductors

M. Takahashi, K. Kubo

cond-mat.mtrl-sciarXiv:cond-mat/0204124

Abstract

Taking into account both random impurity distribution and thermal fluctuations of localized spins, we have performed a model calculation for the carrier (hole) state in Ga1-xMnxAs by using the coherent potential approximation (CPA). The result reveals that a p-hole in the band tail of Ga1-xMnxAs is not like a free carrier but is rather virtually bounded to impurity sites. The carrier spin strongly couples to the localized d spins on Mn ions. The hopping of the carrier among Mn sites causes the ferromagnetic ordering of the localized spins through the double-exchange mechanism. The Curie temperature obtained by using conventional parameters agrees well with the experimental result.

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