Micromagnetic structure analysis of head-on-head-type 180° domain wall in submicron size Co wires

Micromagnetic structures of the 180° domain wall in submicron-size ferromagnetic Co wires were investigated by means of magnetic force microscopy. The domain wall width δ (approximately μm) observed in the Co wire is about 10 times larger than that observed in Co films of the same thickness. From micromagnetic calculations using the Landau-Lifshitz-Gilbert (LLG) equation, the magnetic structure of the 180° domain wall is expected to be a large vortex accompanied by a magnetic ripple structure. This complicated 180° domain wall is formed to reduce the demagnetizing energy due to a head-on-head configuration of the magnetization, which results in a micron-scale transition area of the domain wall. The wire width dependence of the 180° domain wall width obtained by micromagnetic calculations is almost consistent with that measured from the magnetic force micrograph.