Electronic structure of Y1-xCaxVO3 studied by high-energy spectroscopies

We have studied the electronic structure of Y1-xCaxVO3 by x-ray-absorption and resonant photoemission spectroscopy. Upon hole doping the parent Mott-Hubbard insulator YVO3, an insulator-metal transition occurs at around x approximate to 0.5. Resonant V 3p photoemission spectroscopy shows that the states near to the Fermi level are of predominantly V 3d character; in CaVO3, a Fermi edge is present. In the oxygen Is x-ray-absorption spectra, the hole doping is reflected in a large increase of the spectral weight near threshold. Because large changes also appear in the vanadium 2p absorption edge, we conclude that the doped holes are of mixed O and V character. The results also indicate that the amount of O character increases with doping. The development of the photoemission and x-ray-absorption spectral weight differs from the rigid-band-like behavior predicted by one-electron band theory or Hubbard-model calculations. Our O Is x-ray-absorption spectra show good correspondence with the optical spectra, indicating that interband features in the optical spectra are attributed to O 2p to V 3d charge-transfer excitations. [S0163-1829(98)03347-5].