Magnetic interference patterns in long disordered Josephson junctions

TL;DR

This paper investigates how magnetic fields influence supercurrent behavior in long, disordered SNS junctions, revealing a transition from decay to oscillations based on junction width and length ratios.

Contribution

It introduces a new understanding of magnetic interference patterns in long disordered Josephson junctions, highlighting the role of geometric ratios in current behavior.

Findings

Critical current decays in narrow junctions with magnetic field

Damped oscillations of critical current in wide junctions

Edge localization of superconducting correlations in long junctions

Abstract

We study a diffusive superconductor - normal metal - superconductor (SNS) junction in an external magnetic field. In the limit of a long junction, we find that the form of the dependence of the Josephson current on the field and on the length of the junction depends on the ratio between the junction width and the length associated with the magnetic field. A certain critical ratio between these two length scales separates two different regimes. In narrow junctions, the critical current exhibits a pure decay as a function of the junction length or of the magnetic field. In wide junctions, the critical current exhibits damped oscillations as a function of the same parameters. This damped oscillating behavior differs from the Fraunhofer pattern typical for short or tunnel junctions. In wide and long junctions, superconducting pair correlations and supercurrent are localized along the edges of the junction.