Lifting of nodes by disorder in extended-$s$ state superconductors: application to ferropnictides

TL;DR

This paper demonstrates how disorder can induce a full gap in extended-$s$ wave superconductors with nodes, causing a transition from power-law to activated thermodynamic behavior, with implications for ferropnictide experiments.

Contribution

It introduces a simple model showing disorder-induced gapping in extended-$s$ superconductors and discusses its relevance to ferropnictide experimental observations.

Findings

Disorder can gap nodal extended-$s$ superconductors.

Thermodynamic properties shift from power-law to activated behavior.

Application to ferropnictide superconductors is discussed.

Abstract

We show, using a simple model, how ordinary disorder can gap an extended-$s$ ($A_{1g}$) symmetry superconducting state with nodes. The concommitant crossover of thermodynamic properties, particularly the $T$-dependence of the superfluid density, from pure power law behavior to an activated one is exhibited. We discuss applications of this scenario to experiments on the ferropnictide superconductors.