Electronic structure and electron-phonon interaction in transition metal oxides with d0 configuration and lightly doped compounds

Abstract While photoemission spectroscopy has been used as a powerful technique to study the electronic structure of solids, it also reflects the dynamical as well as the static properties of the lattice through electronphonon interaction. In this paper, we present the results of photoemission studies on insulating and lightly carrier-doped oxides and discuss their relevance to the lattice properties of the solids. First, the electronic structure of perovskite-type Ti oxides as well as that of V oxides with empty metal 3 d bands is deduced and discussed in relation to recent microscopic theories of ferroelectricity. Next, we point out that some spectral features of these oxides, when lightly doped with electrons, indicate a sign of strong coupling between the doped electrons and lattice distortion and hence the polaronic nature of the charged carriers.