PHOTOEMISSION-STUDY OF ITINERANT FERROMAGNET CR-1-DELTA-TE

The electronic structures of the itinerant ferromagnets Cr1-deltaTe (d elta=0.05, 0.25, and 0.375) have been studied by photoemission spectro scopy, The valence-band spectra are compared with the density of state s given by band-structure calculations. In spite of the itinerant natu re of the d electrons, disagreement between the photoemission spectra and the band-structure calculations exists in the magnitude of the d-b and exchange splitting and the spectral weight at the Fermi level and 2-4 eV below it: The occupied d band for delta=0.05 is shifted away fr om the Fermi level; the observed spectral weight at the Fermi level is significantly suppressed compared with the band-structure calculation s for delta=0.05 and 0.375, where the nominal d-electron numbers are c lose to integers 4 and 3, respectively. Configuration-interaction clus ter-model calculations have been made for delta=0.05 and 0.375 to expl ain the spectral weight distribution in the high-binding-energy (2-4 e V) region in terms of electron-correlation effects. The d-d on-site Co ulomb energy is estimated to be significant, U similar to 2 eV, and ne arly equal to or smaller than the charge-transfer energy Delta similar to 2-3 eV.