Spatial structure of an individual Mn acceptor in GaAs
  The wave function of a hole bound to an individual Mn acceptor in GaAs is spatially mapped by scanning tunneling microscopy at room temperature and an anisotropic, cross-like shape is observed. The spatial structure is compared with that from an envelope-function, effective mass model, and from a tight-binding model. This demonstrates that anisotropy arising from the cubic symmetry of the GaAs crystal produces the cross-like shape for the hole wave-function. Thus the coupling between Mn dopants in GaMnAs mediated by such holes will be highly anisotropic. 
A.M. Yakunin, A.Yu. Silov, P.M. Koenraad, J.H. Wolter, W. Van Roy, J.   De Boeck, J.-M. Tang, and M.E. Flatte