Magnetic nanostructures in liquid and amorphous materials as probed by small angle neutron scattering

Small angle neutron scattering using polarized neutrons is introduced as a special type of contrast variation for magnetic systems. Examples of diluted magnetic systems are reviewed where low magnetic contrasts had to be analyzed beside strong nuclear contributions or vice versa. In Ferrofluids magnetic core–shell composite particles and magnetic aggregates could be precisely evaluated beside non-magnetic micelles and free surfactants of similar sizes. In more concentrated Co-Ferrofluids an external magnetic field induces a pseudo-crystalline hexagonal ordering which coexists with chain like arrangements of particles. In magnetic glasses magnetization density profiles have been monitored. Magnetically inactive deadlayers or weakly magnetic interfaces separate nanocrystalline ferromagnetic particles from amorphous (para- or ferromagnetic) matrices in soft magnetic materials based on Fe3O4-glass ceramics, Fe–Si–B and Fe–Nb–B alloys. Nanosized inclusions have been detected and identified to be at the origin of the hard magnetic properties of Nd based alloys.