Micromagnetic structure and vortex core reversal in arrays of iron nano-cylinders

The effect of the magnetostatic coupling on the magnetic vortex configuration in arrays of iron nano-cylinders is studied by means of micromagnetic simulations. Systems with neighboring cylinders with parallel or anti-parallel direction of the vortex core are considered. For cylinders with a diameter comparable to the vortex core, the stray field acts either to reduce or to enlarge the vortex core size. The polarity of the vortex core can be reversed by applying a magnetic field parallel to the axis of symmetry of the cylinder. The reversal is initiated by the nucleation of magnetic singularities (Bloch points). For systems with parallel vortex core the analysis of the reversal process shows that magnetostatically coupled cylinders have shorter reversal times.