Josephson Tunnel Junctions in a Magnetic Field Gradient

TL;DR

This study investigates how non-uniform magnetic fields affect the critical current and diffraction patterns of Nb-based Josephson tunnel junctions, revealing skewed patterns and suppression of Fiske resonances.

Contribution

It provides experimental validation of theoretical predictions on magnetic field gradients' effects on Josephson junctions, highlighting new control mechanisms.

Findings

Magnetic diffraction patterns become skewed in non-uniform fields.

Fiske resonances can be suppressed by asymmetric magnetic field profiles.

Results align with recent theoretical models of magnetic field gradients.

Abstract

We measured the magnetic field dependence of the critical current of high quality Nb-based planar Josephson tunnel junctions in the presence of a controllable non-uniform field distribution. We found skewed and slowly changing magnetic diffraction patterns quite dissimilar from the Fraunhofer-like ones typical of a homogeneous field. Our findings can be well interpreted in terms of recent theoretical predictions [R. Monaco, J. Appl. Phys. vol.108, 033906 (2010)] for a uniform magnetic field gradient leading to Fresnel-like magnetic diffraction patterns. We also show that Fiske resonances can be suppressed by an asymmetric magnetic field profile.