Simulation of 3-D micromagnetic structures in thin iron platelet

The three dimensional classical Landau-Lifshitz domain structure in a 30 nm thick (100) iron rectangular platelet was simulated by a 3-D extension of the LaBonte method. Two stable micromagnetic structures with different symmetries and energies were obtained, The four 90 degrees walls of both the structures are of the simple symmetric Neel type. However, the single 180 degrees domain walls in the centres of the two structures have different complicated 3-D cross-tie periodic structures containing circular swirls and cross swirls which we believe correspond to the complicated zip-like patterns that have been observed by magnetic force microscopy. The period of:he spacing of the swirls is comparable to that of these zip-like patterns. fn addition to the 3-D simulation, 2-D simulations were also employed to study the variation in periodicity of the circular and cross swirls with the length of the platelet.