Ab-initio calculations of Co-based diluted magnetic semiconductors Cd1-x Cox X (X=S, Se, Te)

Abstract

Ab-initio calculations are performed to investigate the structural, electronic and magnetic properties of spin-polarized diluted magnetic semiconductors composed of II-VI compounds Cd1-x Cox X (X=S, Se, Te) at x=0.25. From the calculated results of band structure and density of states, the half-metallic character and stability of ferromagnetic state for Cd1-x Cox S, Cd1-x Cox Se and Cd1-x Cox Te alloys are determined. It is found that the tetrahedral crystal field gives rise to triple degeneracy t2g and double degeneracy eg . Furthermore, we predict the values of spinexchange splitting energies +x (d) and +x (p-d) and exchange constants N0 α and N0 β produced by the Co 3d states. Calculated total magnetic moments and the robustness of half-metallicity of Cd1-x Cox X (X=S, Se, Te) with respect to the variation in lattice parameters are also discussed. We also extend our calculations to x=0.50, 0.75 for S compounds in order to observe the change due to increase in Co.