During the early 1980s, advanced techniques for the deposition of ultra-thin metal films were developed. The combination of different types of materials gave rise to new physical phenomena such as the magnetic exchange coupling in superlattices or the exchange bias between ferro and anti-ferro layers. The field was very active because of the associated industrial applications in magnetic field sensors. New types of heterostructures combining magnetic oxides, insulating oxides or magnetic semiconductors are still being developed. Alongside the fabrication of these new meta-materials made of thin films stacking, polarized neutron reflectometry has emerged as a routine tool for the characterization of magnetic hetero-structures. In the recent years, the new developments of polarized reflectivity have been connected to the study of micro and nanostructures, especially micromagnetic structures in multilayers. The technique of off-specular scattering has been developed for the study of the roughness or the micromagnetism at a micrometric scale. For the study of nanometric structures, in the range below 100 nm, grazing incidence Small Angle Scattering is being considered. To cite this article: F.