Two-dimensional quantum transport of multivalley (111) surface state in topological crystalline insulator SnTe thin films

Magneto-transport properties of (111)-oriented single-crystal thin films of SnTe were investigated. SnTe (111) thin films were epitaxially grown on a BaF2 substrate by molecular beam epitaxy. By optimizing the growth conditions and the thickness of the films, the bulk carrier density could be reduced, making it possible to detect the surface transport. In the magneto-conductance (MC) measurement, a cusp-like feature around zero magnetic field was observed, which is attributed to the weak-antilocalization effect of the transport in the topological surface state. Detailed analysis of this negative MC reveals a reduced number of transport channels contributing to the surface transport, suggesting a strong coupling between Dirac valleys on the SnTe (111) surface, as a characteristic feature of the transport in the multivalley structure of TCI.