Remotely induced magnetism in a normal metal using a superconducting spin-valve

• Published in: Nature physics 2016-01, Vol.12 (1), p.57-61
• Main Authors: Flokstra, M. G., Satchell, N., Kim, J., Burnell, G., Curran, P. J., Bending, S. J., Cooper, J. F. K., Kinane, C. J., Langridge, S., Isidori, A., Pugach, N., Eschrig, M., Luetkens, H., Suter, A., Prokscha, T., Lee, S. L.
• Format: Article
• Language: English
• Subjects: 639/766/119/1001; 639/766/119/1003; 639/766/119/997; Atomic; Classical and Continuum Physics; Complex Systems; Condensed Matter Physics; Cooper pairs; Devices; Double layer; Ferromagnetism; letter; Low energy; Magnetic fields; Magnetism; Magnetization; Mathematical and Computational Physics; Molecular; Optical and Plasma Physics; Physics; Superconductivity; Superconductors; Theoretical
• ISSN: 1745-2473; 1745-2481
• DOI: 10.1038/nphys3486

A switchable induced magnetic moment in a non-magnetic metal that is separated from a ferromagnet by a thick superconducting layer contradicts existing models. Superconducting spintronics has emerged in the past decade as a promising new field that seeks to open a new dimension for nanoelectronics by utilizing the internal spin structure of the superconducting Cooper pair as a new degree of freedom 1 , 2 . Its basic building blocks are spin-triplet Cooper pairs with equally aligned spins, which are promoted by proximity of a conventional superconductor to a ferromagnetic material with inhomogeneous macroscopic magnetization 3 . Using low-energy muon spin-rotation experiments we find an unanticipated effect, in contradiction with the existing theoretical models of superconductivity and ferromagnetism: the appearance of a magnetization in a thin layer of a non-magnetic metal (gold), separated from a ferromagnetic double layer by a 50-nm-thick superconducting layer of Nb. The effect can be controlled either by temperature or by using a magnetic field to control the state of the remote ferromagnetic elements, and may act as a basic building block for a new generation of quantum interference devices based on the spin of a Cooper pair.