Ferromagnetic and random spin ordering in diluted magnetic semiconductors

TL;DR

This paper investigates the magnetic ordering in diluted magnetic semiconductors, analyzing how exchange interactions influence the transition between ferromagnetic and disordered phases using percolation theory.

Contribution

It introduces a theoretical framework employing percolation theory to determine the ferromagnetic transition temperature and quantum critical point in these materials.

Findings

Identifies conditions for ferromagnetic ordering

Locates the quantum critical point between phases

Predicts transition temperatures based on system parameters

Abstract

In a diluted magnetic semiconductor system, the exchange interaction between magnetic impurities has two independent components: a direct antiferromagnetic interaction and a ferromagnetic interaction mediated by charge carriers. Depending on the system parameters, the ground state of the system may be ordered either ferromagnetically or randomly. In this paper we use percolation theory to find the ferromagnetic transition temperature and the location of the quantum critical point separating the ferromagnetic phase and a valence bond glass phase.