Disorder effect on chiral edge modes and anomalous Hall conductance in Weyl semimetals

TL;DR

This paper investigates how disorder influences chiral edge states and the anomalous Hall conductance in Weyl semimetals, revealing that disorder can alter the number of edge states and cause the Hall conductance to lose its quantization.

Contribution

It demonstrates that weak disorder affects chiral edge states via mass parameter renormalization and identifies a critical disorder strength where Hall conductance quantization breaks down.

Findings

Weak disorder does not destroy chiral edge states but changes their number.

Hall conductance remains quantized near Weyl nodes at low disorder levels.

Quantization collapses beyond a critical disorder strength, indicating a phase transition.

Abstract

Typical Weyl semimetals host chiral surface states and hence show an anomalous Hall response. Although a Weyl semimetal phase is known to be robust against weak disorder, the influence of disorder on chiral states is not fully clarified so far. We study the behavior of such chiral states in the presence of disorder and its consequences on an anomalous Hall response, focusing on a thin slab of Weyl semimetal with chiral surface states along its edge. It is shown that weak disorder does not disrupt chiral edge states but crucially affects them owing to the renormalization of a mass parameter: the number of chiral edge states changes depending on the strength of disorder. It is also shown that the Hall conductance is quantized when the Fermi level is located near Weyl nodes within a finite-size gap. This quantization of the Hall conductance collapses once the strength of disorder exceeds a critical value, suggesting that it serves as a probe to distinguish a Weyl semimetal phase from a diffusive anomalous Hall metal phase.