Magnetic Interference Patterns and Vortices in Diffusive SNS junctions

TL;DR

This paper theoretically investigates how magnetic fields influence the electronic transport and vortex structures in diffusive SNS junctions, revealing a transition from Fraunhofer patterns to monotonic decay in critical current.

Contribution

It introduces a detailed analysis of magnetic interference patterns and vortex formations in diffusive SNS junctions, highlighting a crossover in critical current behavior based on junction width.

Findings

Critical current pattern transitions from Fraunhofer to monotonic decay.

Vortex structures influence local density of states.

Behavior depends on the relation between junction width and magnetic length.

Abstract

We study theoretically the electronic and transport properties of a diffusive superconductor-normal metal-superconductor (SNS) junction in the presence of a perpendicular magnetic field. We show that the field dependence of the critical current crosses over from the well-known Fraunhofer pattern in wide junctions to a monotonous decay when the width of the normal wire is smaller than the magnetic length \xi_H = \sqrt{\Phi_0/H}, where H is the magnetic field and \Phi_0 the flux quantum. We demonstrate that this behavior is a direct consequence of the magnetic vortex structure appearing in the normal region and predict how such structure is manifested in the local density of states.