  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.
