Effects of ion implantation on the uniaxial anisotropy energy of a magnetic bubble film

Abstract

The effects on ion implantation on the uniaxial anisotropy energy of a magnetic bubble film have been studied. The films have been implanted with 800 KeV helium ions at doses from 10¹⁵ to 3×10¹⁶ ions/cm². The mean projected range for these implantations is 1.9 μm which is 86% of the film thickness. The films exhibit multi‐resonance FMR spectra which indicate an appreciable variation of H_u‐4πM across the film thickness. FMR measurements in conjunction with an acid etching experiment were used to develop a model of this variation of the internal field. The resulting profile indicates the existance of a ’’bulk’’ region (∼70% of film thickness) where H_u‐4πM is relatively constant but appreciably different from that of an unimplanted film. The variation of the anisotropy constant, K_u, as a function of implant dose is studied for this bulk region. Heavily implanted samples also show evidence of a narrow layer where H_u‐4πM has changed greatly from the unimplanted value. This ’’well’’ in the H_u‐4πM profile is deep enough to trap as many as four spin wave modes. The variation of 4πM (using a vibrating sample magnetometer) with implantation dose was also measured. These effects are interpreted in terms of lattice damage incurred during implantation.