Topological surface states on the nonpolar (110) and (111) surfaces of SmB6

Abstract

In order to clarify the controversial issue of the topological nature in a mixed-valent Kondo system, SmB6, we have explored the surface states on the nonpolar (110) surface of SmB6, employing both angle-resolved photoemission spectroscopy (ARPES) experiment and ab initio density-functional theory (DFT) band calculations. Based on ARPES spectroscopic fingerprints and the DFT surface band structures, we ascribe the observed spectral weights at (X) over bar and (Y) over bar on the (110) surface Brillouin zone to topological surface states (TSSs) of "topological insulator (TI)" nature and of "topological crystalline insulator (TCI)" nature, respectively. With varying the chemical potential, the double Dirac cones of the TCI nature exhibit a Lifshitz transition of Fermi surfaces with intriguing spin textures. We have also examined the TSSs on the nearly nonpolar (111) surface of SmB6 in connection with a recently reported ARPES result and proposed a way to probe the Dirac points that are buried in the bulk-projected bands.