Observation of a geometrically constrained domain wall in epitaxial FCC Co small disks

Abstract

The magnetic nanostructure of epitaxial FCC Co/Cu (0 0 1) circular elements ( ∼1.7 μm in diameter) has been imaged with scanning electron microscopy with polarisation analysis. A closed flux configuration (quadrant configuration) is observed for most of the disks, characteristic of systems with cubic anisotropy. However, the measured width of the 90° domain wall varies with the distance from the vortex core, from 70±25 nm up to a value determined by the disk radius. Such a wide domain wall is a consequence of the geometrical constraints imposed by the element, thus defining a geometrically constrained domain wall, as confirmed by micromagnetic simulations.