Ferromagnetic Resonance of a YIG film in the Low Frequency Regime

TL;DR

This paper presents an improved method for characterizing magnetic anisotropy in YIG films using ferromagnetic resonance in the low frequency regime, revealing high sensitivity to anisotropy constants and unusual dynamical behaviors.

Contribution

The study introduces a novel approach to analyze FMR spectra in low frequency regimes, enhancing accuracy in determining magnetic anisotropy constants of cubic symmetry films.

Findings

FMR field sensitivity to anisotropy constants exceeds tenfold below 2 GHz

Unusual phenomena like multiple resonances observed at low frequencies

Small changes in field orientation cause resonance switching at 0.7 GHz

Abstract

An improved method for characterizing the magnetic anisotropy of films with cubic symmetry is described and is applied to an yttrium iron garnet (111) film. Analysis of the FMR spectra performed both in-plane and out-of-plane from 0.7 to 8 GHz yielded the magnetic anisotropy constants as well as the saturation magnetization. The field at which FMR is observed turns out to be quite sensitive to anisotropy constants (by more than a factor ten) in the low frequency (< 2 GHz) regime and when the orientation of the magnetic field is nearly normal to the sample plane; the restoring force on the magnetization arising from the magnetocrystalline anisotropy fields is then comparable to that from the external field, thereby allowing the anisotropy constants to be determined with greater accuracy. In this region, unusual dynamical behaviors are observed such as multiple resonances and a switching of FMR resonance with only a 1 degree change in field orientation at 0.7 GHz.