Magnetoconductivity in Weyl semimetals: Effect of chemical potential and temperature

TL;DR

This paper analyzes magnetoconductivity in Weyl semimetals, revealing conditions for linear magnetoresistance and showing that common approximations do not fully explain experimental results.

Contribution

It provides a detailed theoretical analysis of magnetoconductivity in Weyl semimetals, highlighting the limitations of self-energy approximations in explaining linear magnetoresistance.

Findings

Linear magnetoresistance occurs mainly from the zeroth Landau level.

Temperature has little effect on linear magnetoresistance in the high-field regime.

Self-energy approximations do not fully account for experimental observations.

Abstract

We present the detailed analyses of magneto-conductivities in a Weyl semimetal within Born and self-consistent Born approximations. In the presence of the charged impurities, the linear magnetoresistance can happen when the charge carriers are mainly from the zeroth (n=0) Landau level. Interestingly, the linear magnetoresistance is very robust against the change of temperature, as long as the charge carriers mainly come from the zeroth Landau level. We denote this parameter regime as the high-field regime. On the other hand, the linear magnetoresistance disappears once the charge carriers from the higher Landau levels can provide notable contributions. Our analysis indicates that the deviation from the linear magnetoresistance is mainly due to the deviation of the longitudinal conductivity from the $1/B$ behavior. We found two important features of the self-energy approximation: 1. a dramatic jump of $\sigma_{xx}$, when the $n=1$ Landau level begins to contribute charge carriers, which is the beginning point of the middle-field regime, when decreasing the external magnetic field from high field; 2. In the low-field regime $\sigma_{xx}$ shows a $B^{-5/3}$ behavior and results the magnetoresistance $\rho_{xx}$ to show a $B^{1/3}$ behavior. The detailed and careful numerical calculation indicates that the self-energy approximation (including both the Born and the self-consistent Born approximations) does not explain the recent experimental observation of linear magnetoresistance in Weyl semimetals.