Regensburg 2022 – wissenschaftliches Programm
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TT: Fachverband Tiefe Temperaturen
TT 30: Superconductivity: Poster Session
TT 30.25: Poster
Donnerstag, 8. September 2022, 15:00–18:00, P1
Magnetic-pinning enhancement of the critical current density in type-II superconductor/ferromagnet bilayers — •Elena Zhitlukhina1,2, Maroš Gregor3, and Paul Seidel2 — 1O.O. Galkin Donetsk Institute for Physics and Engineering, Kyiv, Ukraine — 2Friedrich-Schiller-Universität, Jena, Germany — 3Comenius University, Bratislava, Slovak Republic
raditional way to confront the Lorentz-force impact on vortices in type-II superconductors is to immobilize them by introducing microscopic defects suppressing superconductivity locally. An alternative method of enhancing vortex pinning may be realized in planar superconductor/ferromagnet hybrid bi- and trilayers where the nanometer-thin films are placed in close proximity. Magnetic interaction between Abrikosov vortices and the magnetization texture in a ferromagnetic layer can provide a pinning potential for them. In the contribution, we present our study of the magnetic pinning effect in hybrid metallic multilayers formed by weak diluted ferromagnetic (NiCu) and superconducting (NbN) films with ultra-thin insulating (AlN) interlayers between the two strips, cutting off short-range proximity effect. We have found a strong growth of the critical current density followed by moderate changes in the critical temperature. Related analysis shows that the underlying mechanism is indeed magnetic vortex pinning that can be enhanced further through magnetization engineering which will enable optimization of the pinning strength in desired field ranges. The second part of the contribution is devoted to the impact of a charge current through a heavy non-magnetic metal (Pt) generating a transverse spin current. Changes in the critical temperature of an underlying NbN nm-thin layer caused by spin accumulation on a length scale of the spin-flip diffusion length turn out to be well reproducible by concerned phenomenological model. Elena Zhitlukhina’s work was supported by the German Academic Exchange Service (DAAD).