Spectroscopic investigations of the electronic structure and metal-insulator transitions in a Mott-Hubbard system ${\mathrm{La}}_{1-x}{\mathrm{Ca}}_x{\mathrm{VO}}_3$

We investigate the electronic structure of ${\mathrm{La}}_{1-x}{\mathrm{Ca}}_x{\mathrm{VO}}_3$ for various values of x. ${\mathrm{LaVO}}_3$ is a Mott-Hubbard insulator with band gap of about $1.0\pm 0.2\mathrm{eV}.$ Hole doping in this system leads to the growth of a new feature at the Fermi level for $x>~$ 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.