The creation of 360°domain walls in ferromagnetic nanorings by circular applied magnetic fields

Switching behavior in ferromagnetic nanostructures is often determined by the formation and annihilation of domain walls (DWs). In contrast to the more familiar 180°DWs found in most nanostructures, 360°DWs are the proposed transition state of nanorings. This paper examines the formation of 360°DWs created by the application of a circular magnetic field using micromagnetic simulations. 360°DWs form from pairs of canting moments that are oppositely aligned, which each grow to form rotated domains bounded by two 180°DWs and the 180°DWs combine to form 360°DWs. The resulting 360°DWs occur in pairs of opposite topological winding number due to these domains of opposite canting direction. The final number of DWs formed is greatly impacted by symmetry, both of the ring and of the placement of the circular magnetic field. © 2014 AIP Publishing LLC.