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Critical Temperatures of a Two-Band Model for Diluted Magnetic Semiconductors

Research paper by F. Popescu, Y. Yildirim, G. Alvarez, A. Moreo, E. Dagotto

Indexed on: 25 Jan '06Published on: 25 Jan '06Published in: Physics - Materials Science



Abstract

Using Dynamical Mean Field Theory (DMFT) and Monte Carlo (MC) 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 (IB) 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.