Stability of Weyl metals under impurity scattering

TL;DR

This paper studies how impurities affect the electronic properties of Weyl semimetals, revealing that certain impurities do not destroy the Weyl nodes and develop a framework to analyze impurity-induced resonances.

Contribution

It introduces a theoretical framework for analyzing impurity effects in Weyl semimetals, highlighting conditions under which Weyl nodes are protected from impurity scattering.

Findings

Certain impurities do not induce zero-energy resonances, protecting Weyl nodes.

The resonance energy depends on impurity strength and matrix structure.

A general method to analyze impurity-induced resonances in Weyl systems.

Abstract

We investigate the effects of bulk impurities on the electronic spectrum of Weyl semimetals, a recently identified class of Dirac-type materials. Using a $T$-matrix approach, we study resonant scattering due to a localized impurity in tight binding versions of the continuum models recently discussed by Burkov, Hook, and Balents, describing perturbed four-component Dirac fermions in the vicinity of a critical point. The impurity potential is described by a strength $g$ as well as a matrix structure $\Lambda$. Unlike the case in d-wave superconductors, where a zero energy resonance can always be induced by varying the impurity scalar and/or magnetic impurity strength, we find that for certain types of impurity ($\Lambda$), the Weyl node is protected, and that a scalar impurity will induce an intragap resonance over a wide range of scattering strength. A general framework is developed to address this question, as well as to determine the dependence of resonance energy on the impurity strength.