Determination of magnetic profiles in implanted garnets using ferromagnetic resonance

Magnetic properties of the implanted layer in thin garnet films can be obtained from ferromagnetic resonance experiments. Approximate profiles of implantation induced anisotropy can be obtained using perpendicular resonance alone. For maximum information and accuracy, both perpendicular and parallel resonance spectra are needed, and measurements should be made on a number of samples from which varying amounts of the implanted layer have been removed by ion milling. For narrow linewidth materials it is possible to deduce profiles of Hk, 4πM, and A and to determine the value of g in the implanted layer. Methods are presented for the accurate calculation of parallel ferromagnetic resonance (FMR) spectra with depth varying magnetic parameters. This method of analysis has been successfully applied to a yttrium iron garnet (YIG) film substituted with Gd, Tm, Ga, and implanted with He ions at 140 keV with a density of 3 × 10¹⁵cm^-2.