Disordered double Weyl node: Comparison of transport and density-of-states calculations

TL;DR

This paper investigates the stability and transport properties of disordered double Weyl nodes, revealing their instability to disorder and the emergence of a diffusive phase, with observable crossover effects in finite systems.

Contribution

It provides a comparative analysis of density of states and quantum transport in disordered double Weyl nodes, confirming their instability and identifying crossover behaviors.

Findings

Double Weyl nodes are unstable to any finite disorder.

Disorder induces a diffusive phase in double Weyl nodes.

Finite systems show a crossover between pseudodiffusive and diffusive transport.

Abstract

Double Weyl nodes are topologically protected band crossing points which carry chiral charge $\pm2$. They are stabilized by $C_{4}$ point group symmetry and are predicted to occur in $\mathrm{SrSi_{2}}$ or $\mathrm{HgCr_{2}Se_{4}}$. We study their stability and physical properties in the presence of a disorder potential. We investigate the density of states and the quantum transport properties at the nodal point. We find that, in contrast to their counterparts with unit chiral charge, double Weyl nodes are unstable to any finite amount of disorder and give rise to a diffusive phase, in agreement with predictions of Goswami and Nevidomskyy [Phys. Rev. B 92, 214504 (2015)] and Bera, Sau, and Roy [Phys. Rev. B 93, 201302(R) (2016)]. However, for finite system sizes a crossover between pseudodiffusive and diffusive quantum transport can be observed.