Pair breaking due to orbital magnetism in iron-based superconductors

TL;DR

This paper investigates how orbital magnetism-related impurities affect superconductivity in iron-based superconductors, revealing that interband scattering can suppress transition temperatures in conventional types but not in unconventional ones.

Contribution

It introduces a model for impurity effects involving orbital, time-reversal symmetry-breaking impurities and analyzes their impact on superconductivity and density wave phases.

Findings

Interband scattering can suppress transition temperature in conventional superconductors.

Unconventional superconductors may remain unaffected by orbital impurity scattering.

Impurities related to imaginary charge density waves influence phase stability.

Abstract

We consider superconductivity in the presence of impurities in a two-band model suited for the description of iron-based superconductors. We analyze the effect of interband scattering processes on superconductivity, allowing for orbital, i.e., nonspin-magnetic but time-reversal symmetry-breaking impurities. Pair breaking in such systems is described by a nontrivial phase in an interband-scattering matrix element. We find that the transition temperature of conventional superconductors can be suppressed due to interband scattering, whereas unconventional superconductors may be unaffected. We also discuss the stability of density wave phases in the presence of impurities. As an example, we consider impurities associated with imaginary charge density waves that are of interest for iron-based superconductors.