X-ray absorption and inverse photoemission study of Y1-xCaxTiO3

We have performed the O 1s x-ray absorption (XAS) and resonant inverse photoemission spectroscopy (RIPES) in Mott insulator YTiO3, band insulator CaTiO3 and Y0.61Ca0.39TiO3 with a metal-insulator transition. In CaTiO3, the spectrum has strong π* and σ* peaks derived from the Ti 3d-O 2p hybridization bands near the Fermi level. On the other hand the peaks almost disappear in the XAS spectrum of YTiO3. In Y0.61Ca0.39TiO3, the intensities of the π* and σ* structures increase with decreasing temperature, showing that degree of the p-d hybridization increases from the insulator to metal phases. (author)