Controllable creation of skyrmion bags in a ferromagnetic nanodisk

Skyrmion bags are composed of an outer skyrmion and arbitrary inner skyrmions, which have recently been observed in bulk chiral magnets, but still remain elusive magnetic films. Here, we propose a method creating thin-film nanodisk, includes three steps. Firstly, the size is enlarged by vertical field, then skyrmions nucleated at off-center area local current injection, system finally reconstructed due to multiple interskyrmion potentials. Thus, with topological charge up forty can be created. Simulated Lorentz transmission electron microscopy images given facilitate experimental demonstration. Our proposal expected inspire relevant experiments films, pave way for potential spintronic applications based on bags.