Vortices, occurring whenever a flow field ‘whirls’ around a one-dimensional core, are among the simplest topological structures, ubiquitous to many branches of physics. In the crystalline state, vortex formation is rare, since it is generally hampered by long-range interactions: in ferroic materials (ferromagnetic and ferroelectric), vortices are observed only when the effects of the dipole–dipole interaction are modified by confinement at the nanoscale^1,2,3, or when the parameter associated with the vorticity does not couple directly with strain⁴. Here, we observe an unprecedented form of vortices in antiferromagnetic haematite (α-Fe₂O₃) epitaxial films, in which the primary whirling parameter is the staggered magnetization. Remarkably, ferromagnetic topological objects with the same vorticity and winding number as the α-Fe₂O₃ vortices are imprinted onto an ultra-thin Co ferromagnetic over-layer by interfacial exchange. Our data suggest that the ferromagnetic vortices may be merons (half-skyrmions, carrying an out-of plane core magnetization), and indicate that the vortex/meron pairs can be manipulated by the application of an in-plane magnetic field, giving rise to large-scale vortex–antivortex annihilation.

涡旋是流场绕一维核心“旋转”时发生的现象，是最简单的拓扑结构之一，在物理学的许多分支中都是普遍存在的。在晶体状态下，很少形成涡流，因为通常会受到远距离相互作用的阻碍：在铁性材料（铁磁和铁电）中，仅当通过限制纳米级来改变偶极-偶极相互作用的影响时才观察到涡旋^1,2,3，或与涡度相关的参数未直接与应变⁴耦合。在这里，我们观察到反铁磁性赤铁矿旋涡的前所未有的形式（的α-Fe ₂ ö ₃）外延膜，其中主要回旋参数是交错的磁化强度。值得注意的是，用相同的涡和卷绕数为的α-Fe铁磁拓扑对象₂ ö ₃涡流压印到通过界面交换超薄钴铁磁性过层。我们的数据表明，铁磁涡流可能是瓜子（半天空铁电体，带有平面外的铁心磁化强度），并且表明涡旋/梅隆对可以通过施加平面内磁场来操纵，从而导致大规模涡旋-反涡旋an灭。