Electronic structure of [formula omitted] configuration vanadium oxides studied by soft X-ray and hard X-ray photoemission spectroscopy

Abstract

We investigate the electronic structure of 3 d 1 configuration vanadium oxides (VO 2, SrVO 3 and CaVO 3) using soft X-ray (SX) and hard X-ray (HX) photoemission spectroscopy (PES). The valence band spectra of VO 2 in SX- and HX-PES clearly show the opening of a gap at E F across the metal–insulator transition. Spectral changes in the V 2p and O 1s core levels were also observed. In addition, 3 d 1 configuration correlated metals SrVO 3 and CaVO 3 are typical materials whose valence band spectra are compared with dynamical mean-field theory. The V 2p and V 1s core level HX-PES of SrVO 3 and CaVO 3 show clear additional well-screened features. These features originate from bulk screening by a coherent band at E F . These spectra are nicely reproduced by a cluster model calculation, indicating a difference of the parameter V ∗ for the interaction strength between the central V 3d orbitals and the coherent band.