On the nature of ferromagnetism in Ga_{1-x}Mn_xAs semiconductors

A. J. R. da Silva; A. Fazzio; R. R. dos Santos; L. E. Oliveira

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On the nature of ferromagnetism in Ga_{1-x}Mn_xAs semiconductors

A. J. R. da Silva·A. Fazzio·R. R. dos Santos·L. E. Oliveira

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Abstract

We have performed ab initio calculations within the density-functional theory for Ga_{1-x}Mn_xAs diluted semiconductors. Total energy results unambiguously show that a quasi-localized down-spin hole, with strong p-like character, surrounds the fully polarized Mn up-spin d^5-electrons. Calculations indicate that the holes form an essentially dispersionless impurity band, thus rendering effective-mass descriptions of hole states open to challenge. We obtain estimates both for the s = 1/2 hole and S = 5/2 Mn exchange coupling, and for the distance dependence of the effective Mn-Mn exchange interaction. Results demonstrate that the effective Mn-Mn coupling is always ferromagnetic, thus non-RKKY, and intermediated by the antiferromagnetic coupling of each Mn spin to the holes.

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A. J. R. da Silva, A. Fazzio, R. R. dos Santos, L. E. Oliveira. 2003-07-29. On the nature of ferromagnetism in Ga_{1-x}Mn_xAs semiconductors. https://arxiv.org/abs/cond-mat/0307714

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