Magnetic Domain Structure in Coupled Rectangular Nanostructures

The coupling of rectangular magnetic 2000×1000×20 nm
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structures with flux-closure domain configurations is studied using micromagnetic simulations with periodic boundary conditions. In order to understand the origin of the interaction, the magnetic structure of a single element is analyzed in detail to calculate its magnetostatic fringe field. Both, our simulations as well as earlier experimental data reveal an interesting phenomenon: instead of four domains forming the well-known Landau state there are six domains. A consistent magnitude of the effect can be obtained, when the highly susceptible paramagnetic “coating layer” used in the experiment is included in the simulation. The coupling behavior of both, horizontally and vertically aligned arrays of rectangles is explained by the magnetostatic field of the single element. We show that for arrays of elements that have a coating layer inter-element coupling depends strongly on properties of this coating layer.