Arrays of Josephson junctions between unconventional superconductors

TL;DR

This paper investigates large arrays of mesoscopic Josephson junctions between unconventional, gapless superconductors, revealing complex retarded interactions that challenge standard local energy descriptions, with implications for high-T_c superconductor junctions.

Contribution

Introduces a new representation for collective phenomena in arrays of unconventional superconductor junctions and discusses their phase diagram and electrical conductivity.

Findings

Retarded effective action due to tunneling processes

Complexity beyond standard Josephson energy models

Implications for high-T_c superconductor junctions

Abstract

We study large arrays of mesoscopic junctions between gapless superconductors where the tunneling processes of both, particle-hole and Cooper, pairs give rise to a strongly retarded effective action which, contrary to the standard case, can not be readily characterized in terms of a local Josephson energy. This complexity is expected to arise in, e.g., the grain boundary and c-axis junctions in layered high-T_c superconductors. A new representation for describing collective phenomena in this system is introduced, and its phase diagram is discussed, alongside the electrical conductivity.