Damping in yttrium iron garnet film with an interface

TL;DR

This study reveals that the interface between yttrium iron garnet (YIG) and gadolinium iron garnet (GdIG) causes significant damping enhancement in YIG due to spin inhomogeneity and exchange coupling effects.

Contribution

It demonstrates the impact of an interfacial GdIG layer on damping and spin inhomogeneity in YIG films, highlighting the role of interface engineering in magnetic damping.

Findings

Enhanced damping linked to interfacial GdIG layer.

Large inhomogeneous magnetization distribution observed.

Unidirectional resonance field variation indicating spin inhomogeneity.

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 $\Delta H$ reflects a large inhomogeneous distribution of effective magnetization $\Delta 4 \pi M_{eff}$ 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 $H_{r}$, leading to a unidirectional feature. The large extrinsic $\Delta 4\pi M_{eff}$ contribution, apart from the inherent intrinsic Gilbert contribution, manifests enhanced precessional damping in YIG film.