Direct imaging of distorted vortex structures and magnetic vortex annihilation processes in ferromagnetic/antiferromagnetic disk structures

Topological objects, such as magnetic vortices in soft-magnetic thin films, have attracted continued attention over the past 20 years for their unique magnetic reversal behavior and compelling potential applications. In exchange-coupled ferromagnetic/antiferromagnetic microdisks, high-resolution magnetic force microscopy imaging reveals a distorted ferromagnetic vortex structure due to randomly distributed (nonplanar) uncompensated spins at the antiferromagnetic/ferromagnetic interface. Further, in-field imaging and magneto-optical Kerr effect magnetometry demonstrate an unexpected increase in the stability of an otherwise somewhat volatile, intermediate vortex-antivortex state in exchange-coupled microdisks.