The sign of longitudinal magnetoconductivity and the planar Hall effect in Weyl semimetals

TL;DR

This paper investigates the sign change of longitudinal magnetoconductivity and the behavior of the planar Hall effect in Weyl semimetals, providing theoretical insights into their dependence on scattering and magnetic moment effects, with implications for experimental diagnostics.

Contribution

The study offers a comprehensive theoretical analysis of the chiral anomaly signatures in Weyl semimetals, including effects of orbital magnetic moment and scattering, and maps the phase diagram of LMC sign change.

Findings

LMC can change sign from positive to negative depending on scattering and OMM effects.

Planar Hall effect remains positive regardless of OMM or scattering strength.

Theoretical phase diagram predicts conditions for LMC sign reversal.

Abstract

The manifestation of chiral anomaly in Weyl semimetals typically relies on the observation of longitudinal magnetoconductance (LMC) along with the planar Hall effect, with a specific magnetic field and angle dependence. Here we solve the Boltzmann equation in the semiclassical regime for a prototype of a Weyl semimetal, allowing for both intravalley and intervalley scattering, along with including effects from the orbital magnetic moment (OMM), in a geometry where the electric and magnetic fields are not necessarily parallel to each other. We construct the phase diagram in the relevant parameter space that describes the shift from positive to negative LMC in the presence of OMM and sufficiently strong intervalley scattering, as has been recently pointed out for only parallel electric and magnetic fields. On the other hand, we find that the chiral anomaly contribution to the planar Hall effect always remains positive (unlike the LMC) irrespective of the inclusion or exclusion of OMM, or the strength of the intervalley scattering. Our predictions can be directly tested in experiments, and may be employed as new diagnostic procedures to verify chiral anomaly in Weyl systems.