The local density of states of Mn-Mn pairs in GaAs is mapped with cross-sectional scanning tunneling microscopy and compared with theoretical calculations based on envelope-function and tight-binding models. These measurements and calculations show that the crosslike shape of the Mn-acceptor wavefunction in GaAs persists even at very short Mn-Mn spatial separations. The resilience of the Mn-acceptor wave-function to high doping levels suggests that ferromagnetism in GaMnAs is strongly influenced by impurity-band formation. The envelope-function and tight-binding models predict similarly anisotropic overlaps of the Mn wave-functions for Mn-Mn pairs. This anisotropy implies differing Curie temperatures for Mn δ-doped layers grown on differently oriented substrates.
@article{arxiv.cond-mat/0505536,
title = {Spatial structure of Mn-Mn acceptor pairs in GaAs},
author = {A. M. Yakunin and A. Yu. Silov and P. M. Koenraad and J. -M. Tang and M. E. Flatté and W. Van Roy and J. De Boeck and J. H. Wolter},
journal= {arXiv preprint arXiv:cond-mat/0505536},
year = {2009}
}