Photoemission study of itinerant ferromagnet Cr1-δTe

Abstract

The electronic structures of the itinerant ferromagnets (Formula presented)Te (δ=0.05, 0.25, and 0.375) have been studied by photoemission spectroscopy. The valence-band spectra are compared with the density of states given by band-structure calculations. In spite of the itinerant nature of the d electrons, disagreement between the photoemission spectra and the band-structure calculations exists in the magnitude of the d-band exchange splitting and the spectral weight at the Fermi level and 2-4 eV below it: The occupied d band for δ=0.05 is shifted away from the Fermi level; the observed spectral weight at the Fermi level is significantly suppressed compared with the band-structure calculations for δ=0.05 and 0.375, where the nominal d-electron numbers are close to integers 4 and 3, respectively. Configuration-interaction cluster-model calculations have been made for δ=0.05 and 0.375 to explain the spectral weight distribution in the high-binding-energy (2-4 eV) region in terms of electron-correlation effects. The d-d on-site Coulomb energy is estimated to be significant, U∼2 eV, and nearly equal to or smaller than the charge-transfer energy Δ∼2-3 eV. © 1996 The American Physical Society.