Reversible control of spin-polarized supercurrents in ferromagnetic Josephson junctions

• Published in: Nature communications 2014-08, Vol.5 (1), p.4771-4771, Article 4771
• Main Authors: Banerjee, N., Robinson, J.W.A., Blamire, M. G.
• Format: Article
• Language: English
• Subjects: 639/301/119/2793; 639/301/119/995; 639/766/25; Humanities and Social Sciences; multidisciplinary; Science; Science (multidisciplinary)
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/ncomms5771

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-polarized triplet supercurrents in S–F–S Josephson junctions, reversible control of the supercurrent has been impossible because of the robust preconfigured 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. The ability to manipulate spin-polarized supercurrents could enable the development of superconducting spintronic devices whose performance exceeds that of conventional spintronics. Banerjee et al. demonstrate a superconducting analogue of the archetypical spintronic device, the spin valve.