Anharmonic Josephson current in junctions with an interface pair breaking

TL;DR

This paper investigates how interface pair breaking affects the supercurrent and current-phase relation in planar superconducting junctions with strong Josephson coupling, revealing enhanced depairing effects near the interface.

Contribution

It provides a new analytical expression for the anharmonic supercurrent considering interface pair breaking and depairing effects, validated by numerical data.

Findings

Supercurrent is strongly anharmonic near Tc due to interface effects.

Interface pair breaking significantly influences the current-phase relation.

Depairing effects are enhanced near the interface despite small bulk depairing.

Abstract

Planar superconducting junctions with a large effective Josephson coupling constant and a pronounced interface pair breaking are shown to represent weak links with small critical currents and strongly anharmonic current-phase relations. The supercurrent near Tc is described taking into account the interface pair breaking as well as the current depairing and the Josephson coupling-induced pair breaking of arbitrary strengths. A new analytical expression for the anharmonic supercurrent, which is in excellent agreement with the numerical data presented, is obtained. In junctions with a large effective Josephson coupling constant and a pronounced interface pair breaking, the current-induced depairing is substantially enhanced in the vicinity of the interface thus having a crucial influence on the current-phase relation despite a small depairing in the bulk.