A dynamical mean-field approximation study of a tight-binding model for Ga$_{1-x}$Mn$_{x}$As

TL;DR

This study uses dynamical mean-field approximation with a multiband tight-binding model to analyze the magneto-optical properties of Ga$_{1-x}$Mn$_{x}$As, revealing impurity band formation and improved transition temperature predictions.

Contribution

It introduces a material-specific multiband tight-binding approach within DMFA to better predict magnetic and optical properties of Ga$_{1-x}$Mn$_{x}$As.

Findings

Impurity band appears at large magnetic coupling.

Transition temperature predictions align better with experiments.

Optical conductivity exhibits a Drude-like peak suppressed by magnetic coupling.

Abstract

The magneto-optical properties of the ferromagnetic semiconductor Ga$_{1-x}$Mn$_{x}$As are studied within the dynamical mean-field approximation (DMFA). A material-specific multiband $sp^{3}$ tight-binding Hamiltonian is employed for the dispersion of the GaAs host. The calculated density of states shows an impurity band and a distorted valence band for large and moderate values of magnetic coupling, respectively. Upon using the more realistic band structure, the ferromagnetic transition temperature is significantly closer to the experimental results than the previous predictions of $k\cdot p$ models. The optical conductivity shows a Drude-like peak at low frequencies which is suppressed by increasing of the magnetic coupling.