Néel coupling in Co/Cu/Co stripes with unidirectional interface roughness

We investigate the influence of interlayer Neel coupling on the magnetization reversal processes in epitaxial Co(5 nm)/Cu(5 nm)/Co(5 nm) stripes by experimental methods and computer modeling. The stripes with a width of 900 and 1800 nm were formed on a step-bunched Si(111) substrate by molecular beam epitaxy and focused ion beam etching. Uniaxial magnetic anisotropy with the easy axis of the magnetization along the steps is induced in the stripes by the steps of the Si(111) substrate. The stepped structure of the layers in the multilayered stripes reproduces the morphology of the Si(111) substrate. Neel coupling between the Co layers is realized due to the unidirectional roughness at the Co/Cu interfaces caused by the steps of the substrate. Interlayer Neel coupling at the interfaces overcomes antiparallel magnetostatic interaction realized through the sides of the Co layers in the trilayered stripes. We used a modified Neel model in the simulation of the magnetization reversal in the multilayered system with unidirectional interface roughness. The surface energy of Neel coupling was spatially varied against the direction of the magnetization relative to the step edge. The results of micromagnetic simulations of the Co/Cu/Co stripes with spatially non-uniform and averaged surface energies of interlayer Neel coupling are compared and discussed.