Ab initio study of optical properties and magneto-optical Kerr effect in the pyrite compound CoS₂

Abstract

Using a combination of first-principles methods, we have studied the electronic and optical properties, and the magneto-optical Kerr effect in pyrite-structured cobalt sulphide compounds, which are of high technological importance due to their possible half-metallic character. Our study shows that pure CoS₂ can exhibit a large Kerr rotation of greater than 1°, which arises due to the intricate interplay of the band structure effect, the Drude peak, and the relatively small but nonzero spin-orbit effect. The computed Kerr rotation is found to be of the similar kind as that found for compounds containing atoms with strong spin-orbit coupling such as PtMnSb [ V. N. Antonov et al. Phys. Rev. B 56 13012 (1997)]. We have also studied the effect of Fe doping on CoS₂ compound. Our study shows that the Kerr rotation gets suppressed upon doping with Fe.