Positive Magneto-conductivity of Weyl Semimetals in the Ultra-quantum Limit

TL;DR

This study numerically investigates the magnetic transport in disordered Weyl semimetals under strong magnetic fields, revealing positive magneto-conductivity driven by long-range disorder and high Landau level effects, challenging semiclassical theories.

Contribution

It demonstrates that long-range disorder induces positive magneto-conductivity in Weyl semimetals, highlighting mechanisms beyond semiclassical descriptions involving Landau levels and back-scattering suppression.

Findings

Positive magnetic conductivity observed with long-range disorder.

Negative magnetic conductivity occurs with weak short-range disorder.

Back-scattering from high Landau levels is crucial for understanding transport.

Abstract

In this paper, we numerically study the magnetic transport properties of disordered Weyl semimetals (WSM) in the ultra-quantum limit. We find a positive magnetic conductivity for the long-range disorder, although the system tends to have negative magnetic conductivity for the weak short-range disorder. Remarkably, for long-range disorder, such a positive magnetic conductivity cannot be described by the semiclassical Boltzmann transport theory even in the weak disorder limit, and the back-scattering assisted by the high Landau levels is always important. Our results have significant implications for the positive magnetic conductivity recently discovered in the WSM systems, and point out two physical mechanisms: (i) the long-range correlated disorder suppresses the back-scattering among the zeroth Landau level modes; (ii) with increasing the magnetic field, the back-scattering assisted by the high Landau levels will also be suppressed.