Magnetic circular dichroism from the impurity band in III-V diluted magnetic semiconductors

TL;DR

This paper presents a theoretical analysis of magnetic circular dichroism in III-V diluted magnetic semiconductors, highlighting the role of impurity bands and disordered electronic structures, and explains experimental observations.

Contribution

It introduces a real-space Green's function framework to accurately model optical transitions involving impurity bands in highly disordered magnetic semiconductors.

Findings

Magnetic circular dichroism is dominated by transitions between bulk and impurity bands.

The model explains experimental dichroism trends in III-V DMSs.

Antiferromagnetic p-d exchange interactions are key to understanding the results.

Abstract

The magnetic circular dichroism of III-V diluted magnetic semiconductors, calculated within a theoretical framework suitable for highly disordered materials, is shown to be dominated by optical transitions between the bulk bands and an impurity band formed from magnetic dopant states. The theoretical framework incorporates real-space Green's functions to properly incorporate spatial correlations in the disordered conduction band and valence band electronic structure, and includes extended and localized electronic states on an equal basis. Our findings reconcile unusual trends in the experimental magnetic circular dichroism in III-V DMSs with the antiferromagnetic p-d exchange interaction between a magnetic dopant spin and its host.