Optimally Designed Digitally-Doped Mn:GaAs
  We use the ab initio local-density approximation (LDA) to study of exchange interactions and Tc of Ga1&#8722;xMnxAs grown in digitally doped structures. We analyze the crystallographic dependence of exchange interactions predicted by the LDA in terms of the Mn t2 and e levels, and explain the origin of the antiferromagnetic contribution to the total exchange interactions. We exploit this dependence and consider delta-doping in specific orientations where the antiferromagnetic interactions are minimized, to optimize Tc of the system. By including hole doping with the addition of Be in the GaAs host digitally doped Ga1&#8722;xMnxAs is predicted to be significantly above room temperature. 
J. L. Xu and M. van Schilfgaarde