Magnetic interference pattern in planar SNS Josephson junctions

TL;DR

This paper investigates how magnetic fields affect the Josephson current in planar SNS junctions, revealing unusual interference patterns that differ from standard behavior and match recent experimental observations.

Contribution

It provides a theoretical analysis of magnetic interference patterns in ballistic SNS junctions, explaining anomalous behaviors observed experimentally.

Findings

Oscillations of critical current can have periods smaller than flux quantum.

Interference patterns can exhibit nonzero minima.

Damping rates of oscillations can be much smaller than expected.

Abstract

We study the Josephson current through a ballistic normal metal layer of thickness $D$ on which two superconducting electrodes are deposited within a distance $L$ of each other. In the presence of an ({\it in-layer}) magnetic field we find that the oscillations of the critical current $I_c(\Phi)$ with the magnetic flux $\Phi$ are significantly different from an ordinary magnetic interference pattern. Depending on the ratio $L/D$ and temperature, $I_c(\Phi)$-oscillations can have a period smaller than flux quantum $\Phi_0$, nonzero minima and damping rate much smaller than $1/\Phi$. Similar anomalous magnetic interference pattern was recently observed experimentally.