Transport in the metallic regime of Mn doped III-V Semiconductors

TL;DR

This paper models charge transport in Mn-doped GaAs using CPA and Kubo formalism, revealing temperature-dependent magnetoresistance and analyzing Hall effects to understand the underlying physics.

Contribution

It introduces a CPA-based model for transport in Mn-doped III-V semiconductors, incorporating spin splitting and temperature effects, aligning with experimental trends.

Findings

Strong magnetoresistance decreases with temperature

Transport coefficients match experimental trends

Model captures key physics of Mn-doped GaAs

Abstract

The standard model of Mn doping in GaAs is subjected to a coherent potential approximation (CPA) treatment. Transport coefficients are evaluated within the linear response Kubo formalism. Both normal (NHE) and anomalous contributions (AHE) to the Hall effect are examined. We use a simple model density of states to describe the undoped valence band. The CPA bandstructure evolves into a spin split band caused by the $p-d$ exchange scattering with Mn dopants. This gives rise to a strong magnetoresistance, which decreases sharply with temperature. The temperature ($T$) dependence of the resistance is due to spin disorder scattering (increasing with $T$), CPA bandstructure renormalization and charged impurity scattering (decreasing with $T$). The calculated transport coefficients are discussed in relation to experiment, with a view of assessing the overall trends and deciding whether the model describes the right physics. This does indeed appear to be case, bearing in mind that the hopping limit needs to be treated separately, as it cannot be described within the band CPA.