Title

Instabilities of Weyl loop semimetals

Document Type

Article

Publication Date

11-29-2016

Publication Title

New Journal of Physics

ISSN

1367-2630

Volume

Focus on Topological Semimetals

Issue

18

First Page

115006

DOI

http://dx.doi.org/10.1088/1367-2630/18/11/115006

Abstract

We study Weyl-loop semi-metals with short range interactions, focusing on the possible interaction driven instabilities. We introduce an expansion regularization scheme by means of which the possible instabilities may be investigated in an unbiased manner through a controlled weak coupling renormalization group (RG) calculation. The problem has enough structure that a 'functional' RG calculation (necessary for an extended Fermi surface) can be carried out analytically. The leading instabilities are identified, and when there are competing degenerate instabilities a Landau–Ginzburg calculation is performed to determine the most likely phase. In the particle-particle channel, the leading instability is found to be to a fully gapped chiral superconducting phase which spontaneously breaks time reversal symmetry, in agreement with general symmetry arguments suggesting that Weyl loops should provide natural platforms for such exotic forms of superconductivity. In the particle hole channel, there are two potential instabilities—to a gapless Pomeranchuk phase which spontaneously breaks rotation symmetry, or to a fully gapped insulating phase which spontaneously breaks mirror symmetry. The dominant instability in the particle hole channel depends on the specific values of microscopic interaction parameters.