Disorder effects in diluted ferromagnetic semiconductors

TL;DR

This paper investigates how disorder impacts carrier-induced ferromagnetism in diluted III-V semiconductors, emphasizing the importance of impurity scattering and antiferromagnetic exchange in determining magnetic properties.

Contribution

It introduces a two-step approach combining CPA and a generalized RKKY formula to accurately evaluate exchange interactions and Curie temperature considering disorder effects.

Findings

Disorder significantly influences the Curie temperature.

Standard RKKY calculations underestimate the Curie temperature.

Antiferromagnetic exchange can enhance the Curie temperature.

Abstract

Carrier induced ferromagnetism in diluted III-V semi-conductor is analyzed within a two step approach. First, within a single site CPA formalism, we calculate the element resolved averaged Green's function of the itinerant carrier. Then using a generalized RKKY formula we evaluate the Mn-Mn long-range exchange integrals and the Curie temperature as a function of the exchange parameter, magnetic impurity concentration and carrier density. The effect of the disorder (impurity scattering) appears to play a crucial role. The standard RKKY calculation (no scattering processes), strongly underestimate the Curie temperature and is inappropriate to describe magnetism in diluted magnetic semi-conductors. It is also shown that an antiferromagnetic exchange favors higher Curie temperature.