/Co Heterostructure.*

Vortices are among the simplest topological structures. They occur whenever a flow field `whirls' around a one-dimensional core, and are ubiquitous to many branches of physics. In the crystalline state, vortex formation is rare, since it is generally hampered by long-range interactions. Here, we present the discovery of a novel form of crystalline vortices in antiferromagnetic (AFM) hematite (α-Fe₂O₃) epitaxial films, in which the primary whirling parameter is the non-ferroics staggered magnetisation. Remarkably, ferromagnetic (FM) topological objects with the same winding number of the α-Fe₂O₃ vortices are imprinted onto an ultra-thin Co ferromagnetic over-layer by interface exchange. Our data suggest that the FM objects are merons (half-skyrmions), and that the vortex/meron pairs are relatively robust well beyond the Co coercive field, but can be manipulated by the application of a larger in-plane magnetic field (H_par~100mT) , giving rise to large-scale vortex-antivortex annihilation.