Small-angle neutron scattering investigations of magnetic nano­structures using polarized neutrons

Crystalline and magnetic nanostructures have been studied by means of small angle neutron scattering. Using polarised neutrons, the relative contrasts are strongly modified which allowed magnetisation, density and composition profiles at surfaces and interfaces to be evaluated. In nanocrystalline Fe₃O₄ embedded in a glass ceramics matrix the magnetic order is strongly disturbed at the surface of the particles, leading to a magnetically inactive layer. In partially crystallised metallic Fe-Si-B-(Nb,Cu) alloys the presence of a non-magnetic interface between Fe₃Si nanocrystals and the amorphous matrix has been demonstrated which breaks the direct ferromagnetic exchange interactions. In Co-ferrofluids the superparamagnetic core is encapsulated by a shell of surfactant molecules which was found to be impenetrable for the solvent.