Phase stability and ordering in diluted magnetic III–V semiconductors

Abstract

We study the energetics of diluted ferromagnetic III–V semiconductors on an ab initio level using the tight-binding linear muffin-tin orbital–coherent potential approximation method and treating magnetic disorder within the disordered local moment model. Based on calculated total energies, we examine the stability of these alloys with respect to segregation and estimate formation energies of antisite defects and substitutional and interstitial Mn atoms. By using the generalized perturbation method, we calculate the parameters of an effective alloy Ising Hamiltonian including long-range Coulomb interactions. We investigate possible types of ordering, that is correlations of spatial positions of defects using the linearized concentration wave method and Warren–Cowley short-range-order parameters. The theory is illustrated for a GaAs alloy system.