Quantum transport in ultra-thin topological crystalline insulator films

Recent developments have demonstrated the unique properties of conventional topological insulators, such as from dissipation-free transport and the creation of Majorana fermions by interfacing with superconductors, and offered a method for controlling them spatially with magnetic fields. Topological crystalline insulators (TCIs), such as SnTe, offer the same unique properties but an alternate mode of control: crystal symmetry breaking through strain or electric fields. Growth of TCIs thin and uniform enough to access these unique properties is challenging to achieve. This work presents structural and electronic characterization of ultra-thin SnTe films, down to 5nm, grown by molecular beam epitaxy on SrTiO₃ substrates. X-ray diffraction and atomic force microscopy reveal that SnTe films are single-domain and uniform, which is critical to realizing controllable topological properties. Quantum transport effects observed in magnetotransport measurements are consistent with the existence of topological states. To better understand their behavior and inform next steps towards their control, we extract details of the topological states by fitting the magnetotransport over a range of film thicknesses.