Planar Hall effect in c-axis textured films of Bi85Sb15 topological insulator

Measurements of the planar Hall effect (PHE) and anisotropic magnetoresistance (AMR) in polycrystalline films of topological insulator Bi85Sb15 are reported. The observation of PHE and AMR in these films of carrier density ≈2 × 1019 electrons/cm3 is like the behavior of in-plane field transport in thin films of metallic ferromagnets. However, the amplitudes of PHE (ΔρPHE) and AMR (Δρxx) are at variance. ΔρPHE and Δρxx also undergo a sign reversal near ≈160 K. We compare these results with the reported PHE of topological insulators and Weyl semimetals and discuss possible scenarios for anisotropic backscattering of charge carriers in this non-magnetic alloy.