Ballistic feature in disordered Dirac and Weyl semimetals

We study the dynamics of Dirac and Weyl electrons in disordered Dirac and Weyl semimetals. The ballistic feature of the transport is demonstrated by simulating the wave-packet dynamics on lattice models. We show that the ballistic transport survives under a considerable strength of disorder up to the semimetal-metal transition point, which indicates the robustness of Dirac and Weyl semimetals against disorder. We also visualize the robustness of the nodal points and linear dispersion under broken translational symmetry. In addition, scaling behavior of the speed of ballistic transport is confirmed, which provides us an alternative way to evaluate the critical exponent for semimetal-metal transition.