Josephson effect in thin-film superconductor/insulator/superconductor junctions with misaligned in-plane magnetic fields

TL;DR

This paper investigates how misaligned in-plane magnetic fields influence the Josephson current in thin-film superconductor/insulator/superconductor junctions, revealing controllable effects via magnetic field orientation.

Contribution

It provides a self-consistent calculation of the order parameter and demonstrates how exchange field orientation can modulate the Josephson current in S/I/S junctions.

Findings

I_0 and I_m become comparable at low temperatures and near critical fields

Josephson current can be controlled by rotating exchange fields

Analytical results support experimental control of supercurrent

Abstract

We study a tunnel junction consisting of two thin-film s-wave superconductors separated by a thin, insulating barrier in the presence of misaligned in-plane exchange fields. We find an interesting interplay between the superconducting phase difference and the relative orientation of the exchange fields, manifested in the Josephson current across the junction. Specifically, this may be written $I_\text{J}^\text{C} = (I_0+I_m ~ \cos\phi) \sin\Delta\theta$, where I_0 and I_m are constants, and $\phi$ is the relative orientation of the exchange fields while $\Delta\theta$ is the superconducting phase difference. Similar results have recently been obtained in other S/I/S junctions coexisting with helimagnetic or ferromagnetic order. We calculate the superconducting order parameter self-consistently, and investigate quantitatively the effect which the misaligned exchange fields constitute on the Josephson current, to see if I_m may have an appreciable effect on the Josephson current. It is found that I_0 and I_m become comparable in magnitude at sufficiently low temperatures and fields close to the critical value, in agreement with previous work. From our analytical results, it then follows that the Josephson current in the present system may be controlled in a well-defined manner by a rotation of the exchange fields on both sides of the junction. We discuss a possible experimental realization of this proposition.