Microwave properties of Nb/PdNi/Nb trilayers: Observation of flux flow in excess of bardeen-stephen theory

We combine wideband (1-20 GHz) Corbino Disk and Dielectric Resonator (8.2 GHz) techniques to study the microwave properties in Nb/PdNi/Nb trilayers, grown by UHV dc magnetron sputtering, composed by Nb layers of nominal thickness d S =15 nm, and a ferromagnetic PdNi layer of thicknesses d F =1, 2, 8 and 9 nm. We focus on the vortex state. Magnetic fields up to H c2 were applied. The microwave resistivity at fixed H/H c2 increases with d F, eventually exceeding the Bardeen-Stephen flux-flow value. Vortex pinning is very weak at large d F . © 2012 Springer Science+Business Media New York.