Conductivity and band alignment of LaCrO₃/SrTiO₃ (111) heterostructure

In this work, we investigate the electrical transport property and electronic structure of oxide heterostructure LaCrO₃/SrTiO₃ (111). The interface grown under relatively low oxygen partial pressure is found to be metallic with a conducting critical thickness of 11 unit cells of LaCrO₃. This criticality is also observed by x-ray photoelectron spectroscopy, in which the Ti³⁺ signal intensity at the spectrum edge of the Ti-2p_3/2 core level increases rapidly when the critical thickness is reached. The variations of the valence band offset and full width at half maximum of the core-level spectrum with LaCrO₃ thickness suggest that the built-in fields exist both in LaCrO₃ and in SrTiO₃. Two possible origins are proposed:the charge transfer from LaCrO₃ and the formation of a quantum well in SrTiO₃. Our results shed light on the understanding of the doping mechanism at the polar/non-polar oxide interface. Moreover, due to the interesting lattice and spin structure of LCO in the (111) direction, our work provides a basis for further exploring the novel topological quantum phenomena in this system.