Photoemission study of SmCo2.

Abstract

The electronic structure of ${\mathrm{SmCo}}_{2}$ is investigated with photoemission spectroscopy (PES). All the PES spectra are consistent in showing that the bulk Sm ions are trivalent, but that the surface has divalent Sm ions and is probably inhomogeneously mixed valent. Both the Sm 4f valence band and Sm 3d core level PES spectra are found to be substantially broader than those of Sm metal. The observed larger linewidths for ${\mathrm{SmCo}}_{2}$, as compared to those of pure Sm metal, suggest a larger lifetime broadening, probably due to an increased number of valence-band electrons, and a larger 4f hybridization, mainly to Co 3d states. Weak satellite structures are observed in the Co 3d valence band and Co 2p core level PES spectra, indicating Co 3d correlation effects. The comparison of the experimental valence-band PES spectrum with the theoretical Co 3d projected local density of states also suggests that Co 3d correlation effects in ${\mathrm{SmCo}}_{2}$ are non-negligible.