Polar discontinuity governs surface segregation and interface termination: A case study of LaInO3/BaSnO3

Interfacial polar discontinuities play a crucial role in promoting unique two-dimensional electron gases in perovskite systems such as LaInO${}_{3}$/BaSnO${}_{3}$. This study sheds light on the intricate relationship between polar discontinuity compensation and surface segregation, pivotal factors in formation of interfaces. Transmission electron microscopy and density functional theory (DFT) confirm the surface of BaSnO${}_{3}$ (001) are BaO terminated. In contrast, the LaInO${}_{3}$/BaSnO${}_{3}$ interface is found to terminate with SnO2, accompanied by Ba surface segregation as confirmed by electron energy loss spectroscopy and x-ray photoelectron spectroscopy. DFT calculations highlight the significant influence of the polar discontinuity in driving Ba segregation. This study advances our understanding of oxide interfaces by highlighting the critical role of polar discontinuity compensation in shaping the structure of interfaces in perovskite systems.