Josephson junctions in narrow thin-film strips

TL;DR

This paper investigates how the maximum supercurrent in narrow thin-film Josephson junctions depends on magnetic fields, revealing universal behavior and unique field-dependent characteristics influenced by geometry and stray fields.

Contribution

It provides a theoretical analysis of the field dependence of supercurrent in narrow thin-film Josephson junctions, incorporating nonlocal electrodynamics and geometry effects, which was not previously detailed.

Findings

Zeros of supercurrent are equidistant at large fields

Maximum supercurrent peaks decrease as 1/√H with increasing field

Supercurrent behavior is universal and geometry-dependent

Abstract

We study the field dependence of the maximum supercurrent in narrow edge-type thin-film Josephson junctions. It is assumed that the junction extends across thin-film strip of width W that is much less than the Pearl length; the film thickness is much less than the London penetration depth. We calculate the maximum supercurrent within nonlocal Josephson electrodynamics, which takes into account the stray fields affecting tunneling currents. In the case when W is much less than the thin-film Josephson length, the phase difference along the junction depends only on the junction geometry and the applied field, but is independent of the Josephson critical current density, i.e., it is universal. Zeros of the maximum supercurrent are equidistant only in large fields (unlike the case of junctions with bulk banks); they are spaced by a field that is much smaller than the one of bulk junctions. Peaks of the maximum supercurrent decrease inversely proportional to the square root of the applied field, i.e., slower than 1/H for the bulk.