Ferromagnetic resonance in ion-implanted garnet bubble films

Abstract

Ferromagnetic resonance spectra in garnet bubble films before and after implantation are reported. These results are in turn used to determine the samples' anisotropy profile. Two sets of Gd0.9YTm 1.1Ga0.44Fe4.56O12 samples of thicknesses 328 nm and 555 nm were used in these experiments. The six 328 nm samples were implanted with 2×1016 H ions/cm2 at 50 keV while the six 555 nm samples were implanted with 1014 Ne ions/cm2 at 200 keV. FMR spectra of all 12 samples before and after implantation were observed. In general, the unimplanted films show only one resonance peak each while the implanted ones show four such peaks in their spectra. After ion-milled to various thicknesses, the changes in mode intensity and position of these peaks were carefully measured. From the intensity A n and resonance field Hon vs thickness h curves, it has been possible to ascertain the uniaxial anisotropy variation across the thickness of the film. Whereas the anisotropy profile obtained for Ne +-implanted films is in qualitative agreement with what would be expected from nuclear-stopping-power ion-damage LSS theory, that for H +-implanted ones do not. Possible causes for these discrepancies are discussed.