Magnetic antivortex formation in pound-key-like nanostructures

Magnetic antivortices have potential for applications but they are considerably more difficult to create than their topological counterpart, the vortex state. Here, we describe a method to generate isolated magnetic antivortex (AV) states reliably in pound-key-like patterned structures. Magnetic force microscopy images confirm that AV states are obtained after a simple two-step magnetic field procedure that involves first a saturating field along the structure diagonal followed by a smaller field applied in the opposing direction. Micromagnetic simulations show that the second field reverses areas of the structure that have lower shape anisotropy first, which facilitates the subsequent antivortex formation. (C) 2013 American Institute of Physics. [http://dx.doi.org/10.1063/1.4795521]