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

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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.
RevTeX 4, 4 two-column pages, 3 .gif figures; submitted to Phys Rev Lett

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Materials Science, Strongly Correlated Electrons

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http://salesiana.dossiersoluciones.com/handle/123456789/21922

Consulte el texto completo en el siguiente enlace:

https://arxiv.org/abs/cond-mat/0307714
 http://arxiv.org/abs/cond-mat/0307714

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arXiv