A disordered RKKY lattice mean field theory for ferromagnetism in diluted magnetic semiconductors

TL;DR

This paper introduces a lattice mean field theory for ferromagnetism in diluted magnetic semiconductors that accounts for disorder and finite mean free path, providing more accurate predictions than traditional models.

Contribution

It develops a novel lattice mean field approach incorporating disorder and finite mean free path effects, improving predictions of magnetic properties in diluted magnetic semiconductors.

Findings

Accurate analytic predictions for Curie temperature (Tc)

Explanation of non-Brillouin magnetization curves

Understanding of Tc dependence on conductivity

Abstract

We develop a lattice mean field theory for ferromagnetic ordering in diluted magnetic semiconductors by taking into account the spatial fluctuations associated with random disorder in the magnetic impurity locations and the finite mean free path associated with low carrier mobilities. Assuming a carrier-mediated indirect RKKY exchange interaction among the magnetic impurities, we find substantial deviation from the extensively used continuum Zener model Weiss mean-field predictions. Our theory allows accurate analytic predictions for Tc, and provides simple explanations for a number of observed anomalies including the non-Brillouin function magnetization curves, the suppressed low-temperature magnetization saturation, and the dependence of Tc on conductivity.