Magnetically induced anisotropy of flux penetration into strong-pinning superconductor/ferromagnet bilayers

Magnetically induced anisotropy of flux penetration into strong-pinning superconductor/ferromagnet bilayers

We studied the impact of soft ferromagnetic permalloy (Py) on the shielding currents in a strong-pinning superconductor—YBa _2 Cu _3 O _7− _δ with Ba _2 Y(Nb/Ta)O _6 nano-precipitates—by means of scanning transmission x-ray microscopy. Typically and in particular when in the thin film limit, superco...

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Bibliographic Details
Main Authors: J Simmendinger, J Hänisch, M Bihler, A M Ionescu, M Weigand, M Sieger, R Hühne, H Rijckaert, I van Driessche, G Schütz, J Albrecht
Format: Article
Language:English
Published: IOP Publishing 2019-01-01
Series:New Journal of Physics
Subjects:
superconductivity
ferromagnet
XMCD
thin film
superconductor/ferromagnet bilayer
Online Access:https://doi.org/10.1088/1367-2630/ab4f56
Description
Summary:We studied the impact of soft ferromagnetic permalloy (Py) on the shielding currents in a strong-pinning superconductor—YBa _2 Cu _3 O _7− _δ with Ba _2 Y(Nb/Ta)O _6 nano-precipitates—by means of scanning transmission x-ray microscopy. Typically and in particular when in the thin film limit, superconductor/ferromagnet (SC/FM) bilayers exhibit isotropic properties of the flux line ensemble at all temperatures. However, in elements with small aspect ratio a significant anisotropy in flux penetration is observed. We explain this effect by local in-plane fields arising from anisotropic magnetic stray fields originated by the ferromagnet. This leads to direction-dependent motion of magnetic vortices inside the SC/FM bilayer. Our results demonstrate that small variations of the magnetic properties can have huge impact on the superconductor.
ISSN:1367-2630

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