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.