Impurity-Semiconductor Band Hybridization Effects on the Critical Temperature of Diluted Magnetic Semiconductors

TL;DR

This study investigates how impurity-semiconductor band hybridization influences the critical temperature of diluted magnetic semiconductors using Monte Carlo and CPA methods, revealing the importance of hole charge and phase segregation tendencies.

Contribution

It introduces a combined Monte Carlo and CPA approach to analyze impurity-band hybridization effects on critical temperature in diluted magnetic semiconductors, highlighting the role of impurity charge.

Findings

Critical temperature depends on hole charge on magnetic impurities.

CPA underestimates the critical temperature compared to Monte Carlo simulations.

Phase segregation instability occurs near the carriers band edges.

Abstract

We have studied the critical temperature of Diluted Magnetic Semiconductors by means of Monte Carlo simulations and Coherent-Potential-Approximation (CPA) calculations. In our model for this syste m, the magnetic ions couple with the carriers through an antiferromagnetic exchange interaction, $J$, and an electrostatic interaction $W$. The effective impurity potential $J-W$ controls the hybridization between the magnetic impurities and the hole charge on the dopants. We find that the critical temperature depends substantially on the hole charge on the magnetic impurities. The CPA critical temperature is always lower than the obtained in the Monte Carlo simulations, although all trends in the simulation results are reproduced in the CPA calculations. Finally we predict the existence of pockets of phase segregation instability close to the carriers band edges.