Two-loop disorder effects on the nematic quantum criticality in $d$-wave superconductors

TL;DR

This paper investigates how two-loop disorder effects influence the nematic quantum criticality in d-wave superconductors, revealing that weak disorder can induce a transition to a diffusive metallic state.

Contribution

It provides a detailed renormalization group analysis showing that random chemical potential becomes relevant at two-loop level, affecting the critical behavior.

Findings

Weak disorder leads to diffusive fermion behavior.

Two-loop corrections make disorder relevant, altering quantum criticality.

Nodal fermions become diffusive due to disorder.

Abstract

The gapless nodal fermions exhibit non-Fermi liquid behaviors at the nematic quantum critical point that is supposed to exist in some $d$-wave cuprate superconductors. This non-Fermi liquid state may be turned into a disorder-dominated diffusive metal if the fermions also couple to a disordered potential that generates a relevant perturbation in the sense of renormalization group theory. It is therefore necessary to examine whether a specific disorder is relevant or not. We study the interplay between critical nematic fluctuation and random chemical potential by performing renormalization group analysis. The parameter that characterizes the strength of random chemical potential is marginal at the one-loop level, but becomes marginally relevant after including the two-loop corrections. Thus even weak random chemical potential leads to diffusive motion of nodal fermions and the significantly critical behaviors of physical implications, since the strength flows eventually to large values at low energies.