Observation of anomalous Meissner screening in Cu/Nb and Cu/Nb/Co thin films
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We have observed the spatial distribution of magnetic flux in Nb, Cu/Nb, and Cu/Nb/Co thin films using muon-spin rotation. In an isolated 50-nm-thick Nb film, we find a weak flux expulsion (Meissner effect) which becomes significantly enhanced when adding an adjacent 40 nm layer of Cu. The added Cu layer exhibits a Meissner effect (due to induced superconducting pairs) and is at least as effective as the Nb to expel flux. These results are confirmed by theoretical calculations using the quasiclassical Green's function formalism. An unexpected further significant enhancement of the flux expulsion is observed when adding a thin (2.4 nm) ferromagnetic Co layer to the bottom side of the Nb. This observed cooperation between superconductivity and ferromagnetism, by an unknown mechanism, forms a key ingredient for developing superconducting spintronics.
Flokstra , M G , Stewart , R , Satchell , N , Burnell , G , Luetkens , H , Prokscha , T , Suter , A , Morenzoni , E , Langridge , S & Lee , S L 2018 , ' Observation of anomalous Meissner screening in Cu/Nb and Cu/Nb/Co thin films ' , Physical Review Letters , vol. 120 , no. 24 , 247001 . https://doi.org/10.1103/PhysRevLett.120.247001
Physical Review Letters
© 2018, American Physical Society. This work has been made available online in accordance with the publisher’s policies. This is the final published version of the work, which was originally published at https://doi.org/10.1103/PhysRevLett.120.247001
DescriptionWe acknowledge the support of the Engineering and Physical Sciences Research Council through Grants No. EP/I031014/1, No. EP/J01060X/1, No. EP/J010634/1, No. EP/J010650/1, and No. EP/L015110/1.
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