Magneto-optics in pure and defective Ga_{1-x}Mn_xAs from first-principles

TL;DR

This study uses first-principles calculations to analyze the magneto-optical Kerr spectra of Ga_{1-x}Mn_xAs, revealing how defects and Mn concentration influence electronic structure and spectral features, aiding defect identification.

Contribution

It provides a detailed first-principles analysis of magneto-optical properties in GaMnAs, clarifying defect roles and spectral origins, and offers a method to distinguish defect types via Kerr spectra comparison.

Findings

Interband transitions dominate Kerr spectra features.

Kerr angle shows a minimum at ~0.5 eV for certain Mn concentrations.

Interstitial Mn spectra resemble experimental results, aiding defect identification.

Abstract

The magneto-optical properties of Ga$_{1-x}$Mn$_{x}$As including their most common defects were investigated with precise first--principles density-functional FLAPW calculations in order to: {\em i}) elucidate the origin of the features in the Kerr spectra in terms of the underlying electronic structure; {\em ii}) perform an accurate comparison with experiments; and {\em iii}) understand the role of the Mn concentration and occupied sites in shaping the spectra. In the substitutional case, our results show that most of the features have an interband origin and are only slightly affected by Drude--like contributions, even at low photon energies. While not strongly affected by the Mn concentration for the intermediately diluted range ($x\sim$ 10%), the Kerr factor shows a marked minimum (up to 1.5$^o$) occurring at a photon energy of $\sim$ 0.5 eV. For interstitial Mn, the calculated results bear a striking resemblance to the experimental spectra, pointing to the comparison between simulated and experimental Kerr angles as a valid tool to distinguish different defects in the diluted magnetic semiconductors framework.