Probing magnetic ordering in multilayers using soft x-ray resonant magnetic scattering

We have carried out resonant magnetic x-ray scattering from Co∕Ru multilayers with weak antiferromagnetic coupling. We have measured hysteresis loops at different points in reciprocal space (specular or diffuse, integer or half-order peaks), which reveal a rich variety of different shapes. These arise from different degrees of mixing of the scattering arising from the field dependence of the order parameters describing the degree of ferromagnetic, antiferromagnetic correlations in the sample, with the off-specular measurements giving information about their lateral extent. We make a comparison with macroscopic measurements that give information about the degree of different forms of magnetic order averaged over the whole sample in real space.