Half-metallic density of states inSr2FeMoO6due to Hund’s rule coupling

Abstract

We have investigated the electronic structure of ${\mathrm{Sr}}_{2}{\mathrm{FeMoO}}_{6}$ by photoemission spectroscopy and band-structure calculations within the local-density $\mathrm{approximation}+U$ $(\mathrm{LDA}+U)$ scheme. In valence-band photoemission spectra, a distinct double-peak feature has been observed near the Fermi level ${(E}_{F}).$ A photon-energy dependence of the spectra and the $\mathrm{LDA}+U$ band-structure calculation have revealed that the first peak crossing ${E}_{F}$ consists of the (Fe+Mo) ${t}_{2g\ensuremath{\downarrow}}$ states and the second peak well below ${E}_{F}$ is dominated by the Fe ${e}_{g\ensuremath{\uparrow}}$ states. This clearly shows that only the down-spin states contribute to the ${E}_{F}$ intensity, thus the half-metallic density of states (DOS) is realized. We point out that the observed half-metallic DOS can be attributed to the strong Hund's rule energy stabilization due to the high-spin ${3d}^{5}$ configuration at the Fe site.