Nonlinear Planar Hall as Another Signature of Chiral Anomaly in Weyl Semimetals*

Weyl semimetals (WSMs) are a newly discovered class of quantum materials which can host a number of exotic quasiparticles called Weyl fermions. One of the defining properties of WSMs is chiral anomaly – a pair of Weyl nodes with opposite chirality act as source and drain of electrons in the presence of electric and magnetic fields that are not perpendicular to each other. To date, the most remarkable phenomenon induced by chiral anomaly is the longitudinal negative magnetoresistance, which is a linear response effect. In this work, we theoretically investigate the transport properties of WSMs in the nonlinear regime, and predict a nonlinear planar Hall effect as another manifestation of chiral anomaly in transport. Intuitively, a steady-state density difference between a pair of Weyl nodes may be established when the chiral pumping and internode relaxation reach a balance, which conspires with anomalous velocity to give rise to the nonlinear Hall effect. In contrast to the intrinsic quantum nonlinear Hall effect, this effect does not rely on a finite Berry curvature dipole.