Cobalt on calcium fluoride: Initial stages of growth and magnetic properties

Epitaxial cobalt films on CaF₂(1 1 0) buffer layers on Si(0 0 1) were grown by molecular beam epitaxy. It is found that Co grows in a face-centered cubic lattice forming nanodimensional islands. The islands tend to align along the parallel grooves which characterize the self-patterned CaF₂(1 1 0) surface grown on Si(0 0 1). Photoemission was used to probe the uniformity of the film and the occurrence of chemical reactions with the substrate. X-ray magnetic circular dichroism at the Co L_2,3 edges was used to access the magnetic properties of the films. The thick Co film presents an in-plane easy magnetization axis along the directions of the grooves of the CaF₂(1 1 0) surface.