Intrinsic negative longitudinal magnetoresistance in elemental bismuth films

In Dirac and Weyl semimetals, large negative longitudinal magnetoresistance (LMR) under parallel electric (E) and magnetic fields (B) is often attributed to the chiral anomaly—the nonconservation of chiral charge between Weyl nodes under an applied E⋅B field. Such observations, however, can be obscured by current jetting, which has been reported in bulk bismuth (Bi) crystals and several Weyl semimetals such as NaP and TaP, where field-induced inhomogeneous current flow produces positive MR along the central spine, where the current density is high, and apparent negative MR along the lateral edges, where the current density is lower. Here, we report intrinsic negative LMR in epitaxial Bi films with the magnetic field applied in-plane. Systematic “squeeze tests” across multiple device geometries—probing resistance along the spine, edges, and under point-contact and uniform current injection—consistently reveal negative LMR, confirming an intrinsic origin. We will briefly discuss possible origins of the effect.