Evolution of a band insulating phase from a correlated metallic phase

We investigate the evolution of the electronic structure in SrRu1-xTixO3 as a function of x using high resolution photoemission spectroscopy, where SrRuO3 is a weakly correlated metal and SrTiO3 is a band insulator. Increase in x leads to an introduction of a local potential different from Ru-O sublattice. The features in the bulk spectra could be captured remarkably well using first principles approaches, and the electron correlation strengths are found to be similar in all the compositions. The surface spectra exhibit a metal-insulator transition at x=0.5 by opening up a soft gap at the Fermi level epsilon(F) and a hard gap appears at higher x values. These results presumably provide an experimental demonstration of the predictions of metal-insulator transition due to local potential and electron correlation in a two-dimensional bipartite lattice using the ionic Hubbard model.