Intermediate Phase between Disordered Weyl Semimetal and Diffusive Metal

Abstract

Quantum phase transitions of disordered three-dimensional (3D) Weyl semimetals (WSMs) are investigated through quantum conductance calculations and finite-size scaling of localization length. Contrary to a previous belief 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. 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 the 3D Gaussian unitary ensemble of Anderson localization transition. The CI phase was confirmed by quantized nonzero Hall conductance in the bulk insulating phase established by localization length calculations. The disorder-induced various plateau-plateau transitions in both WSM and CI phases were 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.