Revisiting magnetotransport in Weyl semimetals

TL;DR

This paper critically examines the role of intra- and internode scattering in Weyl semimetals, showing that internode scattering is necessary for positive magnetoconductance and that strain-induced axial magnetic fields decrease conductance.

Contribution

It clarifies the conditions under which chiral anomaly induces positive magnetoconductance, emphasizing the importance of internode scattering and challenging recent claims about strain effects.

Findings

Intranode scattering alone does not increase LMC.

Weak internode scattering can generate positive LMC.

Strain-induced axial magnetic fields decrease LMC and planar Hall conductance.

Abstract

A series of recent papers have claimed that intranode scattering, alone, can contribute to positive longitudinal magnetoconductance (LMC) due to chiral anomaly (CA) in Weyl semimetals (WSMs). We revisit the problem of CA induced LMC in WSMs, and show that intranode scattering, by itself, does not result in enhancement of LMC. In the limit of zero internode scattering, chiral charge must remain conserved, which is shown to actually decrease LMC. Only in the presence of a non-zero internode scattering (however weak), one obtains a positive LMC due to non-conservation of chiral charge. Even weak internode scattering suffices in generating positive LMC, since it redistributes charges across both the nodes, although on a time scale larger than that of the intranode scattering. Furthermore, our calculations reveal that, in contrast to recent works, in inhomogeneous WSMs strain induced axial magnetic field $B_5$, by itself, leads to negative longitudinal magnetoconductance and a negative planar Hall conductance.