Large planar Hall effect in bismuth thin films

Abstract

The origin of the planar Hall effect (PHE) in various nonmagnetic semimetals has become a subject of considerable interest, especially in regard to the chiral anomaly that several of these semimetals exhibit. Here, we report a large PHE that exceeds several mω cm over a wide range of temperature T and magnetic field B in micron-thick single-crystalline bismuth thin films grown by molecular beam epitaxy techniques. The angular dependence of the PHE and the related anisotropic magnetoresistance (AMR) show complex behaviors as a function of B and T. At high temperatures and in modest magnetic fields, the PHE and AMR can be quantitatively explained by a semiclassical transport model based on the well-established elongated electron and hole pockets of the Fermi surface in bismuth. Although these results establish an anisotropic electronic orbital origin of the PHE, we find that when the electric current is oriented along the binary axis of bismuth, the PHE and AMR behaviors can be well described by a model based on the chiral anomaly in Weyl or Dirac semimetals. However, this model cannot account for these behaviors when the current is rather oriented along the bisectrix axis. Thus, the anisotropy of the PHE is a useful test to check on the validity of the chiral anomaly in semimetals.