Domain structure of circular and ring magnets

Abstract We present the results of a study of the domain structure and the magnetization reversal processes in arrays of circular and ring magnets, obtained by magnetic force microscopy and magnetization measurements. The particles, with outer diameter 0.55 and 2.2 μm, were made of Permalloy films of thickness 24 and 66 nm. In the circular elements two domain configurations were observed: a vortex structure with perpendicular magnetization at the core and a ‘bud’ state. In the ring elements the domain structure was found to depend on the ring width: a flux closed state was formed in wide rings and the ‘onion’ state was observed in narrow rings.