High-resolution observation of magnetization processes in 2 μm × 2 μm × 0.04 μm permalloy particles

Abstract
The magnetization process in an array of 2 μm × 2 μm × 0.04 μm permalloy particles fabricated on a 100 nm carbon membrane was investigated by means of high‐resolution Lorentz microscopy and electron holography in magnetic fields parallel and perpendicular to the film surface. For perpendicular fields, the magnetization reversal was found to begin with the nucleation of a vortex which gradually transformed into a closure domain configuration. At the remanent state, the flux closure was achieved with the generation of a new type of doubled domain wall.