Itinerant ferromagnetism in half-metallicCoS2

Abstract

We have investigated electronic and magnetic properties of the pyrite-type ${\mathrm{CoS}}_{2}$ using the linearized muffin-tin orbital band method. We have obtained the ferromagnetic ground state with nearly half-metallic nature. The half-metallic stability is studied by using the fixed spin moment method. The non-negligible orbital magnetic moment of Co $3d$ electrons is obtained as ${\ensuremath{\mu}}_{L}=0.06{\ensuremath{\mu}}_{B}$ in the local spin-density approximation (LSDA). The calculated ratio of the orbital to spin angular momenta ${L}_{z}{/S}_{z}=0.15$ is consistent with experiment. The effect of the Coulomb correlation between Co $3d$ electrons is also explored with the LSDA + U method. The Coulomb correlation at Co sites is not so large, $U\ensuremath{\lesssim}1 \mathrm{eV},$ and so ${\mathrm{CoS}}_{2}$ is possibly categorized as an itinerant ferromagnet. It is found that the observed electronic and magnetic behaviors of ${\mathrm{CoS}}_{2}$ can be described better by the LSDA than by the $\mathrm{LSDA}+U.$