Negative magnetoresistance in Dirac semimetal Cd₃As₂ with in-plane magnetic field perpendicular to current

Abstract

Topological insulators and semimetals have exotic surface and bulk states with massless Dirac or Weyl fermions, demonstrating microscopic transport phenomenon based on relativistic theory. Chiral anomaly induced negative magnetoresistance (negative MR) under parallel magnetic field and current has been used as a probable evidence of Weyl fermions in recent years. Here we report a novel negative MR result with mutually perpendicular in-plane magnetic field and current in Cd3As2 nanowires. The negative MR has a considerable value with -16% around 1.5 K and could persist to room temperature of 300 K with -1%. The gate tuning and angle dependence of the negative MR demonstrate the mechanism of the observed negative MR is different from chiral anomaly. Percolating current paths induced by charge puddles and disorder might be involved to produce such considerable negative MR. Our results indicate the negative MR effect in topological semimetals involves synergistic effects of many mechanisms despite chiral anomaly.