Exploring the contribution of trapped magnetic flux on magnetization dynamics in thick Nb/Ni80Fe20/Nb trilayers

It has been reported that below the superconducting transition temperature (Tc) of Nb layer, significant resonance field shift was observed in thick Nb/Ni80Fe20(Py)/Nb trilayers, which was subsequently argued that the shift was induced by trapped magnetic flux. We performed two experiments to explore the contribution of trapped magnetic flux: (i) two different states (parallel or antiparallel) between the spin and flux were introduced. (ii) We also prepared a stack structure of Nb/Py/Gd/Nb with two resonance peaks. The results from both experiments indicate that the contribution of trapped magnetic flux negligible to the shift of resonance peaks.