Negative magnetoresistance and sign change of the planar Hall effect due to the negative off-diagonal effective-mass in Weyl semimetals

TL;DR

This paper theoretically explores how negative off-diagonal effective-mass in Weyl semimetals leads to negative magnetoresistance and sign-changing planar Hall effect, independent of topological effects, revealing new mechanisms for galvanomagnetic phenomena.

Contribution

It introduces the role of negative off-diagonal effective-mass in Weyl semimetals as a cause for anomalous galvanomagnetic effects, independent of topological physics.

Findings

Negative longitudinal MR observed due to off-diagonal effective-mass.

Sign change in the planar Hall effect linked to off-diagonal effective-mass.

PHE exhibits a temperature-dependent dip indicating Weyl point detection.

Abstract

We theoretically investigated the magnetoresistance (MR) and planar Hall effect (PHE) in Weyl semimetals based on the semiclassical Boltzmann theory, focusing on the fine structure of the band dispersion. We identified that the negative longitudinal MR and sign change in the PHE occur because of the negative off-diagonal effective-mass with no topological effects or chiral anomaly physics. Our results highlight the crucial role of the off-diagonal effective-mass, which can cause anomalous galvanomagnetic effects. We propose that the PHE creates a dip in their temperature dependence, which enables the experimental detection of the Weyl point.