First-principles investigation of electronic structure, effective carrier masses, and optical properties of ferromagnetic semiconductor CdCr₂S₄

The electronic structures, the effective masses, and optical properties of spinel CdCr₂S₄ are studied by using the full-potential linearized augmented planewave method and a modified Becke-Johnson exchange functional within the density-functional theory. Most importantly, the effects of the spin-orbit coupling (SOC) on the electronic structures and carrier effective masses are investigated. The calculated band structure shows a direct band gap. The electronic effective mass and the hole effective mass are analytically determined by reproducing the calculated band structures near the BZ center. SOC substantially changes the valence band top and the hole effective masses. In addition, we calculated the corresponding optical properties of the spinel structure CdCr₂S₄. These should be useful to deeply understand spinel CdCr₂S₄ as a ferromagnetic semiconductor for possible semiconductor spintronic applications.