Insulating-to-conducting behavior and band profile across the La0.9Ba0.1MnO3/Nb:SrTiO3 epitaxial interface

Abstract

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.