Optimization of Ferromagnetic Resonance Spectra Measuring Procedure for Accurate Gilbert Damping Parameter in Magnetic Thin Films Using a Vector Network Analyzer

We optimize a vector network analyzer ferromagnetic resonance (VNA-FMR) measurement system to study spin dynamics and Gilbert damping parameters of thin ferromagnetic films. In order to obtain accurate damp-ing parameters, careful determination of the susceptibility line-width is required. The measured S-parameters are converted into the corresponding susceptibility through a calibration processes. From the line-width mea-surements, we can successfully extract the saturation magnetizations and Gilbert damping parameters of 5-, 8-, and 10-nm thick Ni81Fe19 (Py) films