Ground-state properties and molecular theory of Curie temperature in the coherent potential approximation of diluted magnetic semiconductors

TL;DR

This paper models the magnetic properties of GaAs-based diluted magnetic semiconductors using CPA and predicts a linear relation between Curie temperature, Kondo coupling, and doping concentration.

Contribution

It introduces a theoretical framework combining CPA and Weiss molecular theory to analyze ground-state properties and Curie temperature in DMS.

Findings

Ferromagnetism is favored at low temperatures.

Impurity bands form only with strong Kondo coupling.

Curie temperature scales linearly with Kondo coupling and doping.

Abstract

Using spin-1/2 description of valence holes and Kondo coupling between local spins and carriers, GaAs-based III-V diluted magnetic semiconductors (DMS)are studied in the coherent potential approximation(CPA). Our calculated relation of ground-state energy and impurity magnetization shows that ferromagnetism is always favorable at low temperatures. For very weak Kondo coupling, the density of states (DOS) of the host semiconductor is not modified much. Impurity band can be generated at the host band bottom only when Kondo coupling is strong enough. Using Weiss molecular theory, we predict a linear relation of Curie temperature with respect to Kondo coupling and doping concentration $x$ if the hole density is proportional to $x$.