Magnetic singularities in self-organized epitaxial cobalt structures

The dependence of the magnetic domain structures on mesoscopic hcp (0001) cobalt structures are reported. For thin Co films grown, islands having a diameter of approximately 100 nm and height from 10 to 30 nm are observed. Domain structure is determined by the size and shape of the islands. As the thickness of the Co layer increases a topologically modulated continuous film is obtained whose domain structures are perturbed by the islands and the pin-holes introduced by the defect sites. The role of local imperfections on the instabilities and/or singularities in the domain structure are discussed.