Damage in garnet films produced by multiple ion implantation

The use of ferromagnetic resonance measurements to characterize the anisotropy profile induced in epitaxial garnet films by multiple ion implantations is described. For a single implantation with He⁺ions, the damage varies substantially with depth and the damaged layer typically has an effective thickness of about 0.3 μm. Such singly implanted samples exhibit multiple resonance modes[1] from which the anisotropy and its variation with depth can be estimated. Multiple implantations with suitably chosen dosages and ion energies reduce the separation between the resonance modes and enhance the intensity of the mode with the highest perpendicular resonance field. This indicates the improved uniformity of the damaged profile and the increased thickness of the damaged layer. The results are interpreted by means of damage profiles obtained by summing the profiles calculated for each implantation using the LSS theory[2]. The ferromagnetic resonance technique for studying the damage produced by ion implantation has two advantages over the previously used differential chemical etching[3]. The technique yields results on profile uniformity in minutes and gives a direct measurement of the stress-induced anisotropy in the multiple ion implanted layer.