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

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-xCoxX (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-xCoxS, Cd1-xCoxSe and Cd1-xCoxTe alloys are determined. It is found that the tetrahedral crystal field gives rise to triple degeneracy t(2g) and double degeneracy e(g). Furthermore, we predict the values of spin-exchange splitting energies Delta(x)(d) and Delta(x)(p-d) and exchange constants N-0 alpha and N-0 beta produced by the Co 3d states. Calculated total magnetic moments and the robustness of half-metallicity of Cd1-xCoxX (X = S, Se, Te) withrespecttothevariationinlattice 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. (C) 2010 Elsevier B.V. All rights reserved.