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Ab initio study of Curie temperatures of diluted III-V magnetic semiconductors

J. Kudrnovsky·I. Turek·V. Drchal·J. Masek·F. Maca·P. Weinberger
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Abstract

The electronic structure of diluted (Ga,Mn)As magnetic semiconductors in the presence of As-antisites and magnetic disorder is studied within the framework of the local spin density approximation. Both the chemical and magnetic disorders are treated using the coherent potential approximation. A ground state with partial disorder in the local moments and with a reduced total magnetic moment appears in the presence of As-antisites. We first estimate the Curie temperature T_c from total energy differences between the ferromagnetic and the paramagnetic state by identifying these with the corresponding energy difference in a classical Heisenberg model. A more systematic approach within the framework of the mean-field approximation to estimate T_c consists in an evaluation of the effective exchange fields acting on the magnetic moment at a given site. The presence of As-antisites strongly reduces the Curie temperature. The results indicate that the effect of impurities on the electronic structure cannot be neglected and influences the Curie temperature non-negligibly. A comparison of the calculated Curie temperatures to existing experimental data indicates an increase of the donor concentration with the increase of the Mn-content.

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J. Kudrnovsky, I. Turek, V. Drchal, J. Masek, F. Maca, P. Weinberger. 2003-02-21. Ab initio study of Curie temperatures of diluted III-V magnetic semiconductors. https://arxiv.org/abs/cond-mat/0302441

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