Xe Ion-Implanted NiFe Thin Films-Behaviors of Xenon and Magnetic Properties

Systematic experiments were performed on xenon ion implantation into permalloy films, in order to understand the effects of implantation of heavy inert ions on microstructures and magnetic properties. Xenon ion implantation always caused crystallization of the partially epitaxially grown permalloy film, so that the grain size increased. In addition, spherical bubbles were clearly observed even at low ion fluence in slightly defocused TEM images. The bubble size varied over several tens of Angstroms with the fluence. In electron diffraction patterns, a weak extra ring became visible when the fluence exceeded about 6 × 10¹⁶/cm². Magnetization measurements showed a large decrease in Ms and Meff when the fluence increased. The origin of the decrease in magnetization is discussed in relation to xenon bubble formation; it is probably attributable to a decrease in the magnetization of permalloy alloy atoms on the bubble surface.