Combined approach of density functional theory and quantum Monte Carlo method to electron correlation in dilute magnetic semiconductors

TL;DR

This paper combines density functional theory and quantum Monte Carlo methods to accurately model electron correlations and magnetic properties in dilute magnetic semiconductors, specifically Ga,Mn)As.

Contribution

It introduces a multi-orbital model parameterized by DFT and solved with QMC, providing realistic insights into magnetic interactions in dilute magnetic semiconductors.

Findings

Reproduces experimental magnetic properties in dilute limit

Identifies long-range ferromagnetic correlations mediated by impurity-host interactions

Detects anisotropic local density of states consistent with STM measurements

Abstract

We present a realistic study for electronic and magnetic properties in dilute magnetic semiconductor (Ga,Mn)As. A multi-orbital Haldane-Anderson model parameterized by density-functional calculations is presented and solved with the Hirsch-Fye quantum Monte Carlo algorithm. Results well reproduce experimental results in the dilute limit. When the chemical potential is located between the top of the valence band and an impurity bound state, a long-range ferromagnetic correlations between the impurities, mediated by antiferromagnetic impurity-host couplings, are drastically developed. We observe an anisotropic character in local density of states at the impurity-bound-state energy, which is consistent with the STM measurements. The presented combined approach thus offers a firm starting point for realistic calculations of the various family of dilute magnetic semiconductors.