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° walls of both the structures are of the simple symmetric Neel type. However, the single 180° 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 the spacing of the swirls is comparable to that of these zip-like patterns. In 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