Evaluation of the magnetization dynamics in various thick YIG films using our proposed measurement technique

Abstract

This paper describes the evaluation of magnetization dynamics in YIG polycrystalline films with various thicknesses using our proposed measurement technique. The saturation magnetostriction ( λs) are approximately less than −1.0×10−6 regardless of the film thickness and are lower than that of bulk polycrystalline YIG, which might be attributed to the structural and/or magnetic inhomogeneities. On the other hand, the in-plane effective damping constant ( αeff) decreases approximately from 0.00384±0.00029 to 0.00316±0.00013 with the increase of film thickness, and their values are much higher than those of nano-meter thick and micro-meter thick YIG films deposited on GGG substrates. The reason for this difference may be that the extrinsic damping originating from the magnetic inhomogeneities are enhanced in the film plane. In addition, αeff slightly increases as λs decreases. This tendency is opposite to those of Ni-Fe and Fe-Si polycrystalline films, and the correlation between αeff and λs does not appear. Therefore, these results suggest that magnetic inhomogeneities are mainly influenced to both αeff and λs in the film plane.