Spectroscopic investigations of the electronic structure and metal-insulator transitions in a Mott-Hubbard system La1-xCaxVO3

We investigate the electronic structure of La1-xCaxVO3 for various values of x. LaVO3 is a Mott-Hubbard insulator with band gap of about 1.0+/-0.2 eV. Hole doping in this system leads to the growth of a new feature at the Fermi level for x greater than or equal to 0.2, suggesting an insulator-to-metal transition. In addition, the metallic compositions show a metal-insulator transition between the bulk and the surface. We separate the surface and bulk electronic structures from the experimental spectra. The evolution of the bulk electronic structure as a function of doping is characterized by a spectral weight transfer from the incoherent to the coherent feature.