Radiative damping in wave guide based FMR measured via analysis of perpendicular standing spin waves in sputtered Permalloy films
Thomas J. Silva, Justin M. Shaw, Hans T. Nembach, Mathias Weiler, Martin Schoen
The damping α of the spinwave resonances in 75 nm, 120 nm, and 200 nm -thick Permalloy films is measured via vector-network- analyzer ferromagnetic-resonance (VNA-FMR). 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. No other contributions were observed. Furthermore, a method to determine the radiative damping in FMR measurements with a single resonance is suggested.