Origin of Magnetic Circular Dichroism in GaMnAs: Giant Zeeman Splitting   versus Spin Dependent Density of States
  We present a unified interpretation of experimentally observed magnetic circular dichroism (MCD) in the ferromagnetic semiconductor (Ga,Mn)As, based on theoretical arguments, which demonstrates that MCD in this material arises primarily from a difference in the density of spin-up and spin-down states in the valence band brought about by the presence of the Mn impurity band, rather than being primarily due to the Zeeman splitting of electronic states. 
M. Berciu, R. Chakarvorty, Y. Y. Zhou, M. T. Alam, K. Traudt, R.   Jakiela, A. Barcz, T. Wojtowicz, X. Liu, J. K. Furdyna, a...
cond-mat.mtrl-sci