Edge effects in the magnetic interference pattern of a ballistic SNS junction

TL;DR

This paper studies how edge effects influence the magnetic interference pattern of a wide ballistic SNS junction, revealing modifications to the critical current behavior under varying magnetic fields.

Contribution

It provides a detailed analysis of edge-induced modifications to the Josephson critical current in wide SNS junctions, highlighting the transition from zero-lifted minima to mesoscopic fluctuation regimes.

Findings

Edge effects lift zeros in $I_c(\

,

) and shift minima towards half-integer flux quanta at weak fields.,

Abstract

We investigate the Josephson critical current $I_c(\Phi)$ of a wide superconductor-normal metal-superconductor (SNS) junction as a function of the magnetic flux $\Phi$ threading it. Electronic trajectories reflected from the side edges alter the function $I_c(\Phi)$ as compared to the conventional Fraunhofer-type dependence. At weak magnetic fields, $B\lesssim \Phi_0/d^2$, the edge effect lifts zeros in $I_c(\Phi)$ and gradually shifts the minima of that function toward half-integer multiples of the flux quantum. At $B>\Phi_0/d^2$, the edge effect leads to an accelerated decay of the critical current $I_c(\Phi)$ with increasing $\Phi$. At larger fields, eventually, the system is expected to cross into a regime of "classical" mesoscopic fluctuations that is specific for wide ballistic SNS junctions with rough edges.