Some factors in the easy axis magnetization of permalloy films

Abstract

Experiments are carried out by transmission electron microscopy on some aspects of the easy axis magnetization reversal process in vacuum condensed permalloy films 100–900 Å thick. An off-focus electron image gives an accurate indication of the local magnetization directions within the films. A favourable configuration at the edges of a saturated film is achieved by domains of rotating magnetization direction. The production of reverse domains at zero field is shown to be a self-perpetuating process. Interactions between moving cross-tie walls and inclusions are studied. A mechanism is proposed for the release of a wall from the influence of an inclusion. Interactions in films below about 200 Å thick sometimes produce 360° walls due to the dispersed easy axis of the films. Three-hundred and sixty degree walls are also produced during magnetization reversal of films with a highly dispersed easy axis without any wall/inclusion interactions.