Damping in yttrium iron garnet film with an interface

Abstract

We report strong damping enhancement in a 200 nm thick 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 rest of the YIG layer. The out-of-plane angular variation of ferromagnetic resonance (FMR) linewidth ∆H reflects a large inhomogeneous distribution of effective magnetization ∆4πM ef f due to the presence of an exchange springlike moments arrangement in YIG. We probe the spin inhomogeneity at the YIG-GdIG interface by performing an in-plane angular variation of resonance field Hr, leading to a unidirectional feature. The large extrinsic ∆4πM ef f contribution, apart from the inherent intrinsic Gilbert contribution, manifests enhanced precessional damping in YIG film.