Two-component approach for thermodynamic properties in diluted magnetic semiconductors

We examine the feasibility of a simple description of Mn ions in III-V diluted magnetic semiconductors (DMS’s) in terms of two species (components), motivated by the expectation that the Mn-hole exchange couplings are widely distributed, especially for low Mn concentrations. We find, using distributions indicated by recent numerical mean field studies, that the thermodynamic properties (magnetization, susceptibility, and specific heat) cannot be fit by a single coupling as in a homogeneous model, but can be fit well by a two-component model with a temperature dependent number of “strongly” and “weakly” coupled spins. This suggests that a two-component description may be a minimal model for the interpretation of experimental measurements of thermodynamic quantities in III-V DMS systems.