Hard X-ray and soft X-ray photoemission study of vanadium oxides

Abstract We study the electronic structure of Mott–Hubbard systems SrVO 3 and CaVO 3 with photoemission spectroscopy (PES) using hard X-rays (HX) ( h ν ∼ 8 keV) and soft X-rays (SX) ( h ν ∼ 900 eV). In HX-PES results, the V 2p core levels of SrVO 3 and CaVO 3 show clear additional intensity, which are not observed in SX-PES. These features originate from bulk screening by coherent states at Fermi level as observed in other 3d transition metal oxides. From the comparison between SrVO 3 and CaVO 3 in HX-PES, the intensity in SrVO 3 is nearly similar to CaVO 3 . The results suggest screening from coherent states is more efficient in HX-PES compared to SX-PES.