| dc.description |
We have performed ab initio calculations within the density-functional theory for Ga<sub>1−x</sub>Mn<sub>x</sub>As diluted semiconductors. Total energy results unambiguously show that a quasi-localized hole, with predominant p-like character, surrounds the fully polarized Mn d<sup>5</sup>-electrons. The calculations indicate that the holes form a relatively 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. The results demonstrate that the effective Mn–Mn coupling is always ferromagnetic, and thus non-RKKY, and is intermediated by the antiferromagnetic coupling of each Mn spin to the holes. |
