Imaging the three dimensional magnetic nanostructure of Co/Pd multilayer media

Multilayers of Co and Pd (or Pt) are well known for magnetization that points out-of-plane, perpendicular to the surface, but local measurements of the in-plane magnetization remain elusive due to a scarcity of measurement techniques. We used SEM with polarization analysis (SEMPA) to study both continuous films and patterned dots made of pressure-graded Co/Pd multilayer media. Images of all three vector components of the remanent surface magnetization show a rich variety of three dimensional magnetic structures in patterned 2 $\mu $m diameter dots. Labyrinth magnetic domains polarized in the up (+z) and down (-z) directions act as sources and sinks, respectively, for the in-plane magnetization vector field. Larger out-of-plane magnetic domains coincide with the presence of in-plane vortices. In some dots, the distribution of magnetization angles is concentrated along the surface of a cone. These results show that in-plane magnetization in real Co/Pd multilayers plays an important role in the domain configuration of the patterned films.