Wideband microwave measurements in Nb/Pd84Ni16/Nb structures and comparison with thin Nb films

We present wideband microwave measurements (1-22 GHz) taken on superconductor/ferromagnet heterostructures with the Corbino disc technique. We apply the technique to Nb/PdNi/Nb trilayers in the vortex state and we compare the results to data taken with the same technique on a Nb thin film. We show that it is possible to directly extract the genuine flux-flow resistivity from our frequency-dependent measurements without overcoming the (depinning) critical current. The characteristic frequency for vortex relaxation can also be estimated, without resorting to a specific model. We find that the F layer determines a weakening of pinning and an enhancement of the flux-flow resistivity with respect to the Nb film.