Abrikosov vortex nucleation and its detrimental effect on superconducting spin pumping in Pt/Nb/Ni80Fe20/Nb/Pt proximity structures

Abstract

We report Abrikosov vortex nucleation in Pt/Nb/Ni80Fe20/Nb/Pt proximity-coupled structures under oblique ferromagnetic resonance that turns out to be detrimental to superconducting spin pumping. By measuring an out-of-plane field-angle θH dependence and comparing with Pt-absent control samples, we show that as θH increases, the degree of enhancement (suppression) of spin pumping efficiency in the superconducting state for the Pt-present (Pt-absent) sample diminishes and it reverts to the normal state value at θH=90∘. This can be explained in terms of a substantial out-of-plane component of the resonance field for the Ni80Fe20 layer (with in-plane magnetization anisotropy and high aspect ratio) that approaches the upper critical field of the Nb, turning a large fraction of the singlet superconductor volume into the normal state.