Abstract

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 freedom1,2. 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 magnetization3. 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.

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Acknowledgements

We acknowledge the support of the EPSRC through Grants No. EP/J01060X, No. EP/J010626/1, No. EP/J010650/1, No. EP/J010634/1 and No. EP/J010618/1, support of a studentship supported by JEOL Europe and the ISIS Neutron and Muon Source, and the support of the RFBR via awards No. 13-02-01452-a, No. 15-52-10045-Ko-a and No. 14-02-90018 Bel-a. All muon experiments were undertaken courtesy of the Paul Scherrer Institute. We thank J. M. Porro for assistance in acquiring the AFM images.

Author information

Affiliations

  1. School of Physics and Astronomy, SUPA, University of St Andrews, St Andrews KY16 9SS, UK

    • M. G. Flokstra
    •  & S. L. Lee
  2. School of Physics and Astronomy, University of Leeds, Leeds LS2 9JT, UK

    • N. Satchell
    • , J. Kim
    •  & G. Burnell
  3. Department of Physics, University of Bath, Claverton Down, Bath BA2 7AY, UK

    • P. J. Curran
    •  & S. J. Bending
  4. ISIS, Rutherford Appleton Laboratory, Oxfordshire OX11 0QX, UK

    • J. F. K. Cooper
    • , C. J. Kinane
    •  & S. Langridge
  5. SEPnet and Hubbard Theory Consortium, Department of Physics, Royal Holloway, University of London Egham, Surrey TW20 0EX, UK

    • A. Isidori
    • , N. Pugach
    •  & M. Eschrig
  6. Skobeltsyn Institute of Nuclear Physics, Lomonosov Moscow State University (SYNP MSU), Leninskie Gory, Moscow 119991, Russia

    • N. Pugach
  7. Labor für Myonspinspektroskopie, Paul Scherrer Institut, CH-5232 Villigen PSI, Switzerland

    • H. Luetkens
    • , A. Suter
    •  & T. Prokscha

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Contributions

J.K. and G.B. developed the samples; M.G.F., S.L.L., N.S., J.F.K.C., H.L. and T.P. performed the muon measurements, in which H.L., A.S. and T.P. provided the beamline support; M.G.F., S.L.L., N.S., J.F.K.C., P.J.C., S.J.B., C.J.K. and S.L. performed various support and characterization measurements; A.I., N.P. and M.E. provided theoretical interpretation of the data and helped writing the paper; G.B. and M.E. helped designing the study; M.G.F. and S.L.L. designed the study, analysed data and wrote the paper. All authors discussed the results and commented on the manuscript.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to M. G. Flokstra.

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DOI

https://doi.org/10.1038/nphys3486

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