Two-dimensional electron liquid at the (111) SmTiO₃/SrTiO₃ interface

Similar to (001) interfaces, a high carrier density, two-dimensional electron liquid (2DEL) is expected to form at (111) RTiO₃/SrTiO₃ interfaces (R is a trivalent rare earth ion). In this study, epitaxial SmTiO₃ layers were grown on (111) SrTiO₃ surfaces using hybrid molecular beam epitaxy. We report on electrical transport measurements and characterize the carrier densities in the 2DEL and the carrier mobilities at these interfaces. The carrier density is in reasonable agreement with the expected carrier density of ∼2 × 10¹⁴cm⁻². Mobility-limiting mechanisms are analyzed and compared with those of (001) interfaces. Collectively, the results indicate that (111) 2DELs are less confined than those at (001) interfaces. These 2DELs should allow for the study of the phenomena induced by the unique topology of the electron system at (111) interfaces