Two Dimensional Diluted Magnetic Semiconductor Systems

TL;DR

This paper develops a comprehensive theory for two-dimensional diluted magnetic semiconductors, accounting for disorder, finite mean free path, and temperature effects, predicting how these factors influence ferromagnetic transition temperatures.

Contribution

It introduces a detailed theoretical framework for 2D diluted magnetic semiconductors that includes disorder, finite temperature RKKY interactions, and density-dependent effects on $T_c$.

Findings

Strong density dependence of $T_c$ predicted.

Disorder and finite mean free path significantly affect magnetic properties.

Finite temperature RKKY interaction alters ferromagnetic transition predictions.

Abstract

We develop a theory for two-dimensional diluted magnetic semiconductor systems (e.g. $\textrm{Ga}_{1-x}\textrm{Mn}_{x}\textrm{As}$ layers) where the itinerant carriers mediating the ferromagnetic interaction between the impurity local moments, as well as the local moments themselves, are confined in a two-dimensional layer. The theory includes exact spatial disorder effects associated with the random local moment positions within a disordered RKKY lattice field theory description. We predict the ferromagnetic transition temperature ($T_{c}$) as well as the nature of the spontaneous magnetization. The theory includes disorder and finite carrier mean free path effects as well as the important correction arising from the {\it finite temperature} RKKY interaction, finding a strong density dependence of $T_{c}$ in contrast to the simple virtual crystal approximation.