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