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. (C) 2020 The Japan Society of Applied Physics