Within the non-linear Ginzburg-Landau (GL) theory, we investigate the vortex structure in a superconducting thin film with a ferromagnetic disk on top of it. Antivortices are stabilized in shells around a central core of vortices (or a giant-vortex) with size-magnetization controlled ``magic numbers''. An equilibrium vortex phase diagram is constructed. The transition between the different vortex phases occurs through the creation of a vortex-antivortex pair under the magnetic disk edge.
Categories: cond-mat.supr-con