Planar Hall effect from the surface of topological insulators

摘要: A prominent feature of topological insulators (TIs) is the surface states comprising spin-nondegenerate massless Dirac fermions. Recent technical advances have made it possible to address transport properties TI thin films while tuning Fermi levels both top and bottom surfaces across point by electrostatic gating. This opened window for studying physics peculiar TIs. Here we report our discovery a novel planar Hall effect (PHE) from surface, which results hitherto-unknown resistivity anisotropy induced an in-plane magnetic field. observed in dual-gated devices bulk-insulating Bi$_{2-x}$Sb$_{x}$Te$_{3}$ films, are gated. The origin PHE time-reversal-breaking field, anisotropically lifts protection fermions back-scattering. key signature field-induced strong dependence on gate voltage with characteristic two-peak structure near explained theoretically using self-consistent T-matrix approximation. provides new tool analyze manipulate future experiments.