Phenomenological unloaded Q-factor theory for magnetostatic straight edge resonators

By exploiting a computerized technique based on an automatic network analyzer, the magnetic full linewidth ?H0 has been measured in the frequency range 1-20 GHz on a series of yttrium iron garnet epilayers having thickness between 9 and 120 ?m. A relevant result is that in the sample having the lowest damping, ?H0 is almost frequency independent in the interval 2-9 GHz. The linewidth for all the three samples investigated exhibits a couple of peaks around 11.8 and 16.3 GHz, respectively. It is also shown that a moderate reducing heat treatment can decrease the linewidth up to 20%. By also utilizing the measurement of the linewidth versus the temperature, a numerical analysis of above results is attempted in terms of an intra-ionic slow relaxation model which leads to physically reasonable values for the involved parameters.