Negative longitudinal magnetoresistance, anisotropic magnetoresistance, and planar Hall effect in epitaxial thin films of elemental Bismuth

Observations of negative longitudinal magnetoresistance (NLMR), anisotropic magnetoresistance (AMR), and the planar Hall effect (PHE) under an in-plane magnetic field are often used as indications of non-trivial topology in non-magnetic material systems. We show NLMR, AMR, and PHE in crystalline epitaxial thin films (< 50 nm) of elemental Bismuth (111) grown by molecular beam epitaxy on intrinsic GaAs (111) substrates. Films were characterized in-situ using scanning tunneling microscopy to confirm topography and density of states. Furthermore, the thickness and temperature dependence of these phenomena are investigated, demonstrating a high degree of tunability. We posit that these observations may be due to the Rashba effect in the surface states of Bi (111), rather than any non-trivial topological effects.