Vortex pinning at individual defects in magnetic nanodisks

We studied the interaction between magnetic vortices and artificial point defects by using micro-Hall magnetometry. Disk-shaped Permalloy particles with diameters between 300 and 800 nm and thicknesses from 20 to 60 nm, which contain a single lithographically defined defect, were examined. Magnetization reversal curves were measured for different in-plane directions of the applied field. The data indicate that the magnetic vortex structure can be pinned at the point defect.