A PHOTOEMISSION AND INVERSE-PHOTOEMISSION STUDY OF CoSb3

Abstract

The valence-band and conduction-band electronic structure of CoSb 3 crystals with a skutterudite type has been investigated by means of ultraviolet photoemission (UPS) with a He discharge lump (hν = 21.2 and 40.8 eV), synchrotron-radiation photoemission (SRPES) and inverse-photoemission spectroscopies (IPES). In the valence bands, the structures at -1.1, -2.5 and -5.8 eV relative to the Fermi level (E F ) are observed in both UPS spectra and SRPES spectra. Taking into account the photoionization cross sections of Co 3d and Sb 5p states and the crystal field splitting of Co 3d states due to the Sb-square ring around Co-ion sites, the main peak at -1.1 eV is attributed mainly to the Co t 2g states, while the Sb 5p states are expected to contribute to the structures at -2.5 and -5.8 eV with a small admixture of Co 3d states. On The other hand, in the conduction bands, a broad feature is observed from E F to ~ 4 eV and a dip is slightly found at around 1 eV. The structures near E F and at around 3.5 eV are considered to be due to the Co e g and hybridization bands between Sb 5p and Co 3d states, respectively.