Nonmonotonic temperature dependence of critical current in diffusive d-wave junctions

TL;DR

This paper investigates how the critical current in diffusive d-wave Josephson junctions varies with temperature, revealing a nonmonotonic behavior caused by competing effects at the interface.

Contribution

It introduces a theoretical analysis of Josephson currents in D/I/DN/I/D junctions with unconventional superconductors, highlighting the impact of interface barriers and midgap states.

Findings

Critical current shows nonmonotonic temperature dependence.

Stronger interface barriers enhance the Josephson current.

Proximity effect and midgap states compete to determine current behavior.

Abstract

We study the Josephson effect in D/I/DN/I/D junctions, where I, DN and D denote an insulator, a diffusive normal metal and a d-wave superconductor, respectively.The Josephson current is calculated based on the quasiclassical Green's function theory with a general boundary condition for unconventional superconducting junctions. In contrast to s-wave junctions, the product of the Josephson current and the normal state resistance is enhanced by making the interface barriers stronger. The Josephson current has a nonmonotonic temperature dependence due to the competition between the proximity effect and the midgap Andreev resonant states.