Radiative damping in waveguide-based ferromagnetic resonance measured via analysis of perpendicular standing spin waves in sputtered permalloy films

The damping a of the spin-wave resonances in 75, 120, and 200 nm thick permalloy films is measured via vector-network-analyzer ferromagnetic resonance (VNA-FMR) in the out-of-plane geometry. Inductive coupling between the sample and the waveguide leads to an additional radiative damping term. The radiative contribution to the over-all damping is determined by measuring perpendicular standing spin waves (PSSWs) in the permalloy films, and the results are compared to a simple analytical model. The damping of the PSSWs can be fully explained by three contributions to the damping: the intrinsic damping, the eddy-current damping, and the radiative damping. It was not necessary to invoke any additional damping contributions to explain the data. Furthermore, a method to determine the radiative damping in FMR measurements with a single resonance is suggested.