Filtering magnetic relaxation mechanisms of YIG(001) thin films using ferromagnetic resonance

摘要

In this work we used the ferromagnetic resonance (FMR) technique to measure the contributions for the magnetic relaxation in Y_3Fe_5O_(12) textured films deposited onto (001) Gd_3Ga_5O_(12) by magnetron sputtering. Through the numerical fitting of the angular dependence of the in-plane FMR linewidth measurements we identified the contribution of the Gilbert, two-magnon and mosaicity relaxation mechanisms. Regarding to the line broadening due to two-magnon mechanism, we interpreted it as a result of rectangular defects distributed over the film plane. The overall defects were decomposed into three crystallography direction chosen according to the in-plane FMR resonance field experimental results. We observed the two-magnon scattering rate being relevant for YIG thickness below 150 nm. Although it is also present for thicker samples, the Gilbert mechanism dominates with mosaicity being very important to corroborate the shape of the angular dependence, but with small amplitude. We point out the relevance of our finding regarding two-magnon scattering effect in YIG thin films, directly impacting in an overestimation of the spin pumping contribution to the FMR line broadening in YIG/ heavy-metal systems.