Disordered double Weyl node

TL;DR

This paper investigates how double Weyl nodes, which are topologically protected band crossings with chiral charge ±2, become unstable under disorder and split into pairs of simple Weyl nodes with chiral charge ±1, revealing their robustness up to a critical disorder level.

Contribution

It demonstrates that double Weyl nodes are unstable in disordered environments and split into simple Weyl nodes, providing insights into their stability and behavior under disorder.

Findings

Double Weyl nodes split into simple Weyl nodes under disorder.

The split nodes are stable up to a critical disorder strength.

The behavior is analogous to elementary Weyl nodes.

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 fate in the presence of quenched disorder by numerical transport calculations and scaling arguments. We find that a double Weyl node is unstable in a disordered environment and splits into a pair of emergent simple Weyl nodes which carry equal chiral charge of $\pm1$. This pair of simple Weyl nodes is robust to disorder up to a certain critical disorder strength, in complete analogy to their `elementary' counterparts.