The effect of Ga-ion irradiation on sub-micron-wavelength spin waves in yttrium-iron-garnet films.

Abstract

We investigate the effect of focused-ion-beam (FIB) irradiation on spin waves with sub-micron wavelengths in yttrium-iron-garnet films. Time-resolved scanning transmission x-ray microscopy was used to image the spin waves in irradiated regions and deduce corresponding changes in the magnetic parameters of the film. We find that the changes of Ga⁺irradiation can be understood by assuming a few percent change in the effective magnetizationMeffof the film due to a trade-off between changes in anisotropy and effective film thickness. Our results demonstrate that FIB irradiation can be used to locally alter the dispersion relation and the effective refractive indexneffof the film, even for submicron wavelengths. To achieve the same change innefffor shorter wavelengths, a higher dose is required, but no significant deterioration of spin wave propagation length in the irradiated regions was observed, even at the highest applied doses.