  La0.9Ba0.1MnO3 is a ferromagnetic insulator in its bulk form, but exhibits
metallicity in thin film form. It has a wide potential in a range of
spintronic-related applications, and hence it is critical to understand
thickness-dependent electronic structure in thin films as well as
substrate/film interface effects. Here, using electrical and in-situ
photoemission spectroscopy measurements, we report the electronic structure and
interface band profile of high-quality layer-by-layer-grown La0.9Ba0.1MnO3 on
single crystal Nb:SrTiO3 substrates. A transition from insulating-to-conducting
was observed with increasing La0.9Ba0.1MnO3 thickness, which was explained by
the determined interface band diagram of La0.9Ba0.1MnO3/Nb: SrTiO3, where a
type II heterojunction was formed.
