A possible method to confirm $\pm s$-wave pairing state using the Riedel anomaly in Fe-pnictide superconductors

TL;DR

This paper proposes a theoretical method to identify the $ ext{±}s$-wave pairing symmetry in Fe-pnictide superconductors by detecting a unique vanishing ac-Josephson current caused by the Riedel anomaly, serving as a clear signature.

Contribution

It introduces a novel approach using the Riedel anomaly in ac-Josephson current to confirm $ ext{±}s$-wave pairing in Fe-pnictides, which was not previously established.

Findings

Vanishing ac-Josephson current at specific voltages indicates $ ext{±}s$-wave pairing.

The phenomenon is absent in conventional s-wave superconductors.

Proposes an experimental signature for $ ext{±}s$-wave symmetry detection.

Abstract

We theoretically propose a method to identify $\pm s$-wave order parameter in recently discovered Fe-pnictide superconductors. Our idea uses the Riedel anomaly in ac-Josephson current through an SI($\pm$ S) (single-band s-wave superconductor/insulator/$\pm$s-wave two-band superconductor) junction. We show that the Riedel peak effect leads to vanishing ac-Josephson current at some values of biased voltage. This phenomenon does not occur in the case when the $\pm s$-wave superconductor is replaced by a conventional s-wave one, so that the observation of this vanishing Josephson current would be a clear signature of $\pm s$-wave pairing state in Fe-pnictide superconductors.