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

TL;DR

This study uses DMFT and Monte Carlo simulations to analyze the ferromagnetic transition temperature in a two-band model for Diluted Magnetic Semiconductors, revealing that optimal Tc occurs when impurity bands overlap and is significantly higher than in one-band models.

Contribution

It demonstrates that a two-band model with overlapping impurity bands yields higher Tc, emphasizing the importance of multiband descriptions for DMS.

Findings

Tc is maximized when impurity bands fully overlap.

Optimal Tc is about twice that of one-band models.

Overlap of impurity bands enhances ferromagnetic transition temperature.

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.