Phase diagrams of disordered Weyl semimetals

TL;DR

This paper investigates how disorder influences the topological and electronic properties of Weyl semimetals, revealing that weak disorder preserves nodal points and induces a novel non-quantized anomalous Hall insulator phase.

Contribution

It provides detailed phase diagrams for three lattice models, showing universal and model-specific effects of disorder on Weyl semimetals and their topological responses.

Findings

Weak disorder preserves Weyl nodes up to the diffusive limit.

Disorder causes Weyl nodes to move within the Brillouin zone.

A non-quantized anomalous Hall insulator phase emerges due to disorder.

Abstract

Weyl semimetals are gapless quasi-topological materials with a set of isolated nodal points forming their Fermi surface. They manifest their quasi-topological character in a series of topological electromagnetic responses including the anomalous Hall effect. Here we study the effect of disorder on Weyl semimetals while monitoring both their nodal/semi-metallic and topological properties through computations of the localization length and the Hall conductivity. We examine three different lattice tight-binding models which realize the Weyl semimetal in part of their phase diagram and look for universal features that are common to all of the models, and interesting distinguishing features of each model. We present detailed phase diagrams of these models for large system sizes and we find that weak disorder preserves the nodal points up to the diffusive limit, but does affect the Hall conductivity. We show that the trend of the Hall conductivity is consistent with an effective picture in which disorder causes the Weyl nodes move within the Brillouin zone along a specific direction that depends deterministically on the properties of the model and the neighboring phases to the Weyl semimetal phase. We also uncover an unusual (non-quantized) anomalous Hall insulator phase which can only exist in the presence of disorder.