A Generic Phase between Disordered Weyl Semimetal and Diffusive Metal

TL;DR

This study reveals an intermediate Chern insulator phase in disordered 3D Weyl semimetals, challenging previous claims of a direct transition to a diffusive metal, and characterizes the universal critical behavior of these transitions.

Contribution

It demonstrates the existence of an intermediate Chern insulator phase between Weyl semimetal and diffusive metal phases due to internode scattering, with detailed critical exponents and phase properties.

Findings

Identification of an intermediate Chern insulator phase

Critical exponent of localization length is approximately 1.3

Disorder-induced plateau-plateau transitions explained by self-consistent Born approximation

Abstract

Quantum phase transitions of three-dimensional (3D) Weyl semimetals (WSMs) subject to uncorrelated on-site disorder are investigated through quantum conductance calculations and finite-size scaling of localization length. Contrary to previous claims that a direct transition from a WSM to a diffusive metal (DM) occurs, an intermediate phase of Chern insulator (CI) between the two distinct metallic phases should exist due to internode scattering that is comparable to intranode scattering. The critical exponent of localization length is $\nu\simeq 1.3$ for both the WSM-CI and CI-DM transitions, in the same universality class of 3D Gaussian unitary ensemble of the Anderson localization transition. The CI phase is confirmed by quantized nonzero Hall conductances in the bulk insulating phase established by localization length calculations. The disorder-induced various plateau-plateau transitions in both the WSM and CI phases are observed and explained by the self-consistent Born approximation. Furthermore, we clarify that the occurrence of zero density of states at Weyl nodes is not a good criterion for the disordered WSM, and there is no fundamental principle to support the hypothesis of divergence of localization length at the WSM-DM transition.