Monte Carlo simulations of an impurity band model for III-V diluted magnetic semiconductors

TL;DR

This study uses Monte Carlo simulations to analyze an impurity band model for III-V diluted magnetic semiconductors, revealing ferromagnetic transition behavior and spatial inhomogeneity in magnetization consistent with experiments.

Contribution

It introduces a perturbative Monte Carlo method for efficient simulation of a carrier-impurity model in diluted magnetic semiconductors, providing new insights into magnetic inhomogeneities.

Findings

Ferromagnetic transition at low temperatures.

Spatial inhomogeneity of Mn magnetization.

Qualitative agreement with experimental data.

Abstract

We report the results of a Monte Carlo study of a model of (III,Mn)V diluted magnetic semiconductors which uses an impurity band description of carriers coupled to localized Mn spins and is applicable for carrier densities below and around the metal-insulator transition. In agreement with mean field studies, we find a transition to a ferromagnetic phase at low temperatures. We compare our results for the magnetic properties with the mean field approximation, as well as with experiments, and find favorable qualitative agreement with the latter. The local Mn magnetization below the Curie temperature is found to be spatially inhomogeneous, and strongly correlated with the local carrier charge density at the Mn sites. The model contains fermions and classical spins and hence we introduce a perturbative Monte Carlo scheme to increase the speed of our simulations.