PHOTOEMISSION-STUDY OF SMCO2

The electronic structure Of SmCo2 is investigated with photoemission s pectroscopy (PES). All the PES spectra are consistent in showing that the bulk Sm ions are trivalent, but that the surface has divalent Sm i ons and is probably inhomogeneously mixed valent. Both the Sm 4f valen ce band and Sm 3d core level PES spectra are found to be substantially broader than those of Sm metal. The observed larger linewidths for Sm Co2, as compared to those of pure Sm metal, suggest a larger lifetime broadening, probably due to an increased number of valence-band electr ons, and a larger 4f hybridization, mainly to Co 3d states. Weak satel lite structures are observed in the Co 3d valence band and Co 2p core level PES spectra, indicating Co 3d correlation effects. The compariso n of the experimental valence-band PES spectrum with the theoretical C o 3d projected local density of states also suggests that Co 3d correl ation effects in SmCo2 are non-negligible.