Reversible control of spin-polarised supercurrents in ferromagnetic Josephson junctions

TL;DR

This paper demonstrates reversible control of spin-polarised supercurrents in ferromagnetic Josephson junctions by manipulating magnetic inhomogeneity with small magnetic fields, supported by experimental data and micromagnetic simulations.

Contribution

It introduces a multi-layer ferromagnetic barrier allowing magnetic orientation control, enabling full modulation of triplet supercurrents, advancing understanding of magnetic state influence in supercurrent behavior.

Findings

Reversible supercurrent control achieved via magnetic orientation manipulation.

Experimental data aligns with theoretical models of magnetic state effects.

Finite element micromagnetic simulations support experimental observations.

Abstract

Magnetic inhomogeneity at a superconductor (S)/ferromagnet (F) interface converts spin-singlet Cooper pairs into spin-one triplet pairs. These pairs are immune to the pair-breaking exchange field in F and support a long-range proximity effect. Although recent experiments have confirmed the existence of spin-polarised triplet supercurrents in S-F-S Josephson junctions, reversible control of the supercurrent has been impossible because of the robust pre-configured nature of the inhomogeneity. Here we use a barrier comprising three F layers whose relative magnetic orientation, and hence the interfacial inhomogeneity, can be controlled by small magnetic fields; we show that this enables full control of the triplet supercurrent and, by using finite element micromagnetic simulations, we can directly relate the experimental data to the theoretical models which provide a general framework to understand the role played by magnetic states in long-range supercurrent modulation.