Damping in yttrium iron garnet films with interface

Abstract

We report strong damping enhancement in yttrium iron garnet (YIG) film due to spin inhomogeneity at the interface. The growth-induced thin interfacial gadolinium iron garnet (GdIG) layer antiferromagnetically (AFM) exchange couples with the top YIG layer. The out-of-plane angular variation of ferromagnetic resonance linewidth $\mathrm{\ensuremath{\Delta}}H$ reflects a large inhomogeneous distribution of the effective magnetization $\mathrm{\ensuremath{\Delta}}4\ensuremath{\pi}{M}_{\mathrm{eff}}$ due to the presence of the aforementioned AFM exchange coupling between the interfacial-GdIG and top-YIG layer. We probe the spin inhomogeneity at the YIG-GdIG interface by performing an in-plane angular variation of resonance field ${H}_{r}$, leading to a unidirectional feature. The large extrinsic $\mathrm{\ensuremath{\Delta}}4\ensuremath{\pi}{M}_{\mathrm{eff}}$ contribution, apart from the inherent intrinsic Gilbert contribution, manifests enhanced precessional damping in the YIG film.