Effect of GGA on the half-metallicity of the itinerant ferromagnet CoS₂

The half-metallicity of CoS₂, important for its possible use in spintronic applications, is investigated by means of density functional full-potential linearized augmented plane wave calculations within both the local spin-density approximation (LSDA) and the generalized gradient approximation (GGA). In contrast with earlier and our own predictions employing the LSDA, we find that CoS₂ is clearly half-metallic with use of the GGA for the exchange-correlation functional. While the GGA induced modifications of the band structure are significant, they are limited to only the e_g↓ state which is responsible for producing the half-metallicity, while leaving all other features the same as those obtained by LSDA. We address the recently measured reflectivity spectra and rectify the assignments given for their underlying optical transitions.