Critical temperatures of the two-band model for diluted magnetic semiconductors

Using dynamical mean field theory and Monte Carlo simulations, we study the ferromagnetic transition temperature (Tc) of a two-band model for diluted magnetic semiconductors (DMS), varying coupling constants, hopping parameters, and carrier densities. We found that Tc is optimized at all fillings p when both impurity bands fully overlap in the same energy range, namely when the exchange couplings J and bandwidths are identical. The optimal Tc is found to be about twice larger than the maximum value obtained in the one-band model, showing the importance of multiband descriptions of DMS at intermediate J 's.