The anisotropic effect of hexagonal warping on the transport

In the presence of hexagonal warping (HW), the surface state of a topological insulator (TI) exhibits anisotropic Fermi surface. In this work, we study the transport properties of a TI junction, focusing on the influence of anisotropic effect of the HW on the scattering. We establish general expressions for calculating the scattering with an arbitrary angle between TI surface and the potential step, and find that the transmission probability and conductance have a strong dependence on the angle, making TI junction a promising platform for studying the geometry control of transport. Remarkably, we find that the HW can induce a triple refraction, which gives rise to an anomalous increase of the transmission probability when varying incident angle. The general expressions here for calculating the scattering can be extended to the systems with trigonally and tetragonally warped Fermi surface. (C) 2018 Elsevier B.V. All rights reserved.