Origin of planar Hall effect in type-II Weyl semimetal MoTe2

TL;DR

This study investigates the origin of the planar Hall effect in type-II Weyl semimetal MoTe2, revealing that anisotropic resistivity mainly results from orbital magnetoresistance rather than chiral anomaly effects.

Contribution

The paper clarifies that the observed planar Hall effect in MoTe2 is primarily due to orbital magnetoresistance, not the chiral anomaly, challenging previous assumptions.

Findings

PHE and AMR fit theoretical formulas well

Anisotropic resistivity arises from orbital MR, not negative MR

Negative MR is absent, indicating dominant orbital MR

Abstract

Besides the negative longitudinal magnetoresistance (MR), planar Hall effect (PHE) is a newly emerging experimental tool to test the chiral anomaly or nontrivial Berry curvature in Weyl semimetals (WSMs). However, the origins of PHE in various systems are not fully distinguished and understood. Here we perform a systematic study on the PHE and anisotropic MR (AMR) of Td-MoTe2, a type-II WSM. Although the PHE and AMR curves can be well fitted by the theoretical formulas, we demonstrate that the anisotropic resistivity arises from the orbital MR (OMR), instead of the negative MR as expected in the chiral anomaly effect. In contrast, the absence of negative MR indicates that the large OMR dominates over the chiral anomaly effect. This explains why it is difficult to measure negative MR in type-II WSMs. We argue that the measured PHE can be related with the chiral anomaly only when the negative MR is simultaneously observed.