Electronic and magnetic properties of Ga1-xMnxAs: Role of Mn defect bands - art. no. 035207

Ga1-xMnxAs and related semiconductors are under intense investigation for t he purpose of understanding the ferromagnetism in these materials, pursuing higher T-c, and, finally, for realizing semiconductor electronic devices t hat use both charge and spin. In this work, the electronic and magnetic str uctures of Ga1-xMnxAs (x=3.125%, 6.25%, 12.5%, 25.0%, 50.0%) are studied by first-principles full-potential linearized augmented plane wave calculatio ns with the generalized-gradient approximation. The ferromagnetic state is lower in energy than the paramagnetic and antiferromagnetic states. It is c onfirmed that Mn atoms stay magnetic with well localized magnetic moments. The calculated band structure shows that Mn doping also forms defect bands, and makes (Ga,Mn)As p-type conducting by providing holes. Furthermore, an s-d population inversion is found in the Mn electronic configuration, which results from the strong Mn p-d mixing. The induced As moments are substant ial (about -0.15 mu (B) per Mn atom, and almost independent of x)-in accord with a recent observed negative As magnetic circular dichroism signal.