$\mathrm{L}{\mathrm{a}}_{0.9}\mathrm{B}{\mathrm{a}}_{0.1}\mathrm{Mn}{\mathrm{O}}_3$ 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 $\mathrm{L}{\mathrm{a}}_{0.9}\mathrm{B}{\mathrm{a}}_{0.1}\mathrm{Mn}{\mathrm{O}}_3$ on single-crystal $\mathrm{Nb}:\mathrm{SrTi}{\mathrm{O}}_3$ substrates. A transition from insulating-to-conducting was observed with increasing $\mathrm{L}{\mathrm{a}}_{0.9}\mathrm{B}{\mathrm{a}}_{0.1}\mathrm{Mn}{\mathrm{O}}_3$ thickness, which was explained by the determined interface band diagram of $\mathrm{L}{\mathrm{a}}_{0.9}\mathrm{B}{\mathrm{a}}_{0.1}\mathrm{Mn}{\mathrm{O}}_3$/$\mathrm{Nb}:\mathrm{SrTi}{\mathrm{O}}_3$, where a type II heterojunction was formed.

• Received 28 June 2017
• Revised 12 September 2017

DOI:https://doi.org/10.1103/PhysRevB.96.165103