Spatially resolved observation of domain-wall propagation in a submicron ferromagnetic NOT-gate

Domain-wall propagation under an external magnetic field in a submicron ferromagnetic ring integrated with a NOT-junction is investigated by magnetic force microscopy and micromagnetic modeling. Within a certain magnetic field range, one head-to-head or tail-to-tail domain wall propagates in the structure. Magnetic fields above this range cause nucleation of additional domain walls in the ring structure while fields below this range are not able to switch the NOT-junction magnetization. This explicitly demonstrates the magnetization reversal, operation, and failure modes of a magnetic NOT-junction.