The electronic structure of Mn doped GaAs and GaN have been examined within a multiband Hubbard model. By virtue of the positioning of the Mn d states, Mn doped GaAs is found to belong to the p-d metal regime of the Zaanen-Sawatzky-Allen phase diagram and its variants while Mn doping in GaN belongs to the covalent insulator regime. Their location in the phase diagram also determines how they would behave under quantum confinement which would increase the charge transfer energy. The

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... stability of Mn doped GaAs, we find, increases with confinement therefore providing a route to higher ferromagnetic transition temperatures.