Observation of the chiral anomaly induced negative magneto-resistance in 3D Weyl semi-metal TaAs

TL;DR

This paper provides the first experimental evidence of negative magneto-resistance caused by the chiral anomaly in the Weyl semi-metal TaAs, confirming theoretical predictions about its unique transport properties.

Contribution

It reports the first direct observation of chiral anomaly-induced negative magneto-resistance in TaAs, a time-reversal invariant Weyl semi-metal, supported by quantum oscillation analysis.

Findings

Detection of clear Shubnikov de Haas oscillations at weak magnetic fields

Berry phase analysis indicating Weyl points presence

Observation of negative magneto-resistance linked to chiral anomaly

Abstract

Weyl semi-metal is the three dimensional analog of graphene. According to the quantum field theory, the appearance of Weyl points near the Fermi level will cause novel transport phenomena related to chiral anomaly. In the present paper, we report the first experimental evidence for the long-anticipated negative magneto-resistance generated by the chiral anomaly in a newly predicted time-reversal invariant Weyl semi-metal material TaAs. Clear Shubnikov de Haas oscillations (SdH) have been detected starting from very weak magnetic field. Analysis of the SdH peaks gives the Berry phase accumulated along the cyclotron orbits to be {\pi}, indicating the existence of Weyl points.