Half-metallic density of states in Sr2FeMoO6 due to Hund's rule coupling

We have investigated the electronic structure of Sr2FeMoO6 by photoemission spectroscopy and band-structure calculations within the local-density approximation+U (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 LDA+U band-structure calculation have revealed that the first peak crossing E-F consists of the (Fe+Mo) t(2gdown arrow) states and the second peak well below E-F is dominated by the Fe e(gup arrow) 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.