Electronic investigation on topological surface states of Bi0.9Sb0.1

Abstract

Topological surface states of Bi0.9Sb0.1 single crystal were reinvestigated by using the angle-resolved photoemission measurements. We identify the surface band topology near the (M) over bar point with two separate electron Fermi surfaces. It provides an indisputable picture of two topological surface bands between the (Gamma) over bar and (M) over bar points, excluding the possible existence of a hypothetic trivial surface band proposed previously. We also examine the detailed nature of topological surface bands and estimate the Fermi velocity v(F). The surface band near the (Gamma) over bar point displays a characteristic warping structure originating from the rhombohedral symmetry, and the v(F) turns out to be highly anisotropic in both the hexagon-shaped electron and teardrop-shaped hole Fermi surface. Our investigation clarifies the topological surface states on Bi0.9Sb0.1, which is essential for the topological spintronics applications. Copyright (C) EPLA, 2017