STM/STS INVESTIGATIONS OF TOPOLOGICAL SURFACE STATES ON SB FILMS

Abstract

Motivated by the unique electronic properties of Sb and its fascinating potential in topological insulators, Sb films were investigated using in-situ STM/STS. Specifically, two surfaces of the film as well as the interaction between them play a vital role in determining the topological properties. So we firstly analyzed surface states solely from the upper surface. According to FT-STS experiments and DFT simulations, the topological suppression for scatterings between opposite spin directions can be revealed, indicating that Sb(111) thick films indeed possess topological surface states. Then the influence of the lower surface was considered. We proved that on ~3nm Sb thin films, part of surface states degenerate to quantum well states and lose their topological properties. Finally the substrate effect was investigated. CdSe(0001) polar surfaces as the substrate may induce new properties for topological insulators on top, so the kinetic growth process and detailed analysis of the surface reconstruction were performed.