Double Vortex Interaction in Micron-Sized Elliptical Ni$_{80}$ Fe$_{20}$ Elements Studied by Real-Time Kerr Microscopy

We have used full-field optical Kerr microscopy to study the double-vortex interaction in epitaxially grown micron-sized elliptical ferromagnetic thin films by observing magnetization-switching behavior. Both micromagnetic simulation and experimental measurements were carried out to determine the origin of the observed magnetization reversal process. It was found that the direction in which each vortex core rotates largely depends on the edge spins that are not saturated by an externally applied magnetic field. It was also found that the switching fields depend significantly on the relative direction in which the vortex cores rotate.