Nucleation and annihilation of magnetic vortices in Pacman-like nanodots observed by micro-Hall probes

We have used micro-Hall probe for the study of vortex dynamics in micromagnetic objects with lowered symmetry. The Pacman-like nanodot of the diameter of 1 µm was placed directly on the Hall probe and the signal was red in band resistance configuration. We show that the vortex nucleation and annihilation, as well as s-and c-state creation/annihilation are clearly visible on the magnetization reversal characteristics at 77 K. The experimental characteristics is in good agreement with the one calculated by micromagnetic simulations.