EXCHANGE INTERACTION IN DILUTED MAGNETIC SEMICONDUCTORS - CRYSTAL-STRUCTURE-INDUCED ANISOTROPY

In this paper, we employ the model developed by Larson et al. to calculate the exchange interaction between magnetic ions in diluted magnetic semiconductors in a method that incorporates explicitly the intrinsic symmetry of the host crystals. We find that the symmetry of the wave function, and thus the interaction matrix element, could induce strong directional dependence of the exchange interaction despite the fact that superexchange is mediated via virtual excitations near the center of the Brillouin zone, where the band energy is essentially isotropic.