  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.
