Quantum Transport in Topological Semimetals under Magnetic Fields

TL;DR

This paper reviews quantum transport phenomena in topological semimetals under magnetic fields, discussing weak localization and negative magnetoresistance effects, and analyzing their dependence on magnetic field strength, carrier density, and disorder.

Contribution

It provides a comprehensive analysis of magnetotransport behaviors in topological semimetals, including fitting formulas and the impact of disorder and Berry curvature.

Findings

Weak anti-localization can be fitted with a specific magnetoconductivity formula.

Negative magnetoresistance depends on carrier density and Berry curvature effects.

High-field magnetoconductivity can be linear for certain scattering potentials.

Abstract

Topological semimetals are three-dimensional topological states of matter, in which the conduction and valence bands touch at a finite number of points, i.e., the Weyl nodes. Topological semimetals host paired monopoles and antimonopoles of Berry curvature at the Weyl nodes and topologically protected Fermi arcs at certain surfaces. We review our recent works on quantum transport in topological semimetals, according to the strength of the magnetic field. At weak magnetic fields, there are competitions between the positive magnetoresistivity induced by the weak anti-localization effect and negative magnetoresistivity related to the nontrivial Berry curvature. We propose a fitting formula for the magnetoconductivity of the weak anti-localization. We expect that the weak localization may by induced by inter- alley effects and interaction effect, and occur in double-Weyl semimetals. For the negative magnetoresistance induced by the nontrivial Berry curvature in topological semimetals, we show the dependence of the negative magnetoresistance on the carrier density. At strong magnetic fields, specifically, in the quantum limit, the magnetoconduction depends on the type and range of the scattering potential of disorder. The high-field positive magnetoconductivity may not be a compelling signature of the chiral anomaly. For long-range Gaussian scattering potential and half filling, the magnetoconductivity can be linear in the quantum limit. A minimal conductivity is found at the Weyl nodes although the density of states vanishes there.