Polarized SANS for probing magnetic nanostructures

Cross-sections for small angle neutron scattering, using non-polarised and polarised neutrons, with and without polarisation analysis, are derived for single-domain ferromagnetic particles when inter-particle correlations are taken into account. The potential for magnetic contrast variation is demonstrated by investigations of poly disperse magnetic colloids. Size distributions, compositions and magnetic moments of magnetic composites and magnetic aggregates were determined precisely independently from that of non-magnetic micelles and free surfactants of similar sizes. Nuclear and magnetic inter-particle correlations have been extracted from the scattering signals by using polarisation analysis via a 3He filter cell.