Origin of bulk uniaxial anisotropy in zinc-blende dilute magnetic   semiconductors
  It is demonstrated that the nearest neighbor Mn pair on the GaAs (001) surface has a lower energy for the [-110] direction comparing to the [110] case. According to the group theory and the Luttinger's method of invariants, this specific Mn distribution results in bulk uniaxial in-plane and out-of-plane anisotropies. The sign and magnitude of the corresponding anisotropy energies determined by a perturbation method and ab initio computations are consistent with experimental results. 
M. Birowska, C. Sliwa, J. A. Majewski, T. Dietl
cond-mat.mtrl-sci