Disorder-induced phase transitions in double Weyl semimetals

TL;DR

This paper explores how different types of disorder affect phase transitions in double Weyl semimetals, revealing disorder-induced topological phase changes and the emergence of diffusive metallic states.

Contribution

It provides a detailed numerical analysis of disorder effects in DWSMs, including phase diagrams and the role of orbital and on-site disorders, using transfer matrix and Kubo formula methods.

Findings

Disorder induces phase transitions from DWSM to 3D QAH and insulator phases.

Orbital disorder can generate Weyl nodes and induce phase transitions.

Disorder effects are explained via self-consistent Born approximation.

Abstract

The double Weyl semimetal (DWSM) is a newly proposed topological material that hosts Weyl points with chiral charge n=2. The disorder effect in DWSM is investigated by adopting the tight-binding Hamiltonian. Using the transfer matrix method and the noncommutative Kubo formula, we numerically calculate the localization length and the Hall conductivity in the presence of the on-site nonmagnetic disorder or orbital (spin-flip) disorders, and give the corresponding global phase diagrams. For the on-site nonmagnetic disorder, the system undergoes the DWSM-3D quantum anomalous hall (3D QAH) and normal insulator (NI)-DWSM phase transitions, and evolves into the diffusive metal (DM) phase before being localized by strong disorders, which is consistent with the Weyl semimetal. For \sigma_x orbital disorder, we find that increasing disorder can generate a pair of Weyl nodes at the boundary of the Brillouin zone and induce a 3D QAH-DWSM phase transition. Then we investigate the combined effect of orbital disorders for both disordered 3D QAH phase and DWSM phase. The disorder-induced transitions can be well understood in terms of an effective medium theory based on self-consistent Born approximation.