Chirality-dependent planar Hall effect in inhomogeneous Weyl semimetals

TL;DR

This paper demonstrates that inhomogeneous Weyl semimetals can exhibit a planar Hall effect driven by strain-induced chiral gauge potentials, independent of chiral anomaly, with potential applications in chirality-based electronics.

Contribution

It reveals a new mechanism for planar Hall effect in inhomogeneous Weyl semimetals caused by strain, without relying on chiral anomaly, and explores the resulting chirality-dependent phenomena.

Findings

PHE exists in IWSMs due to strain-induced chiral gauge potential.

A phase shift leads to a finite chirality-dependent PHE (CPHE).

Small tilt in Weyl nodes can generate pure CPHE without magnetic field.

Abstract

The planar Hall effect (PHE), the appearance of an in-plane transverse voltage in the presence of co-planar electric ($\mathbf{E}$) and magnetic ($\mathbf{B}$) fields, occurs in regular Weyl semimetals (WSMs) as one of the fundamental manifestations of chiral anomaly. A major issue, therefore, is whether there are alternate route to PHE, without invoking chiral anomaly. We demonstrate that PHE exists in an inhomogeneous Weyl semimetal (IWSM) even in the absence of the aforesaid anomaly. Using semiclassical Boltzmann transport theory, we show that PHE appears in an IWSM due to the strain-induced chiral gauge potential, which couples to the Weyl fermions of opposite chirality with opposite sign. Our study shows a resultant phase shift in the current associated with opposite chirality Weyl nodes, which, remarkably, leads to a finite chirality-dependent planar Hall effect (CPHE) in the IWSMs. Interestingly, we show that a small tilt in the Weyl node can generate a pure CPHE even in the absence of an applied magnetic field. The CPHE has important implications in `chiralitytronics'. We also discuss the experimental feasibility of these novel effects of strain in type-I IWSMs.