Small-angle scattering of orientated magnetic structures and applications to magnetic colloids

When polarized neutrons are used in small-angle scattering (SANSPOL) to investigate oriented magnetic structures, the interplay of the external magnetic field and the local magnetisation with the structure orientation leads to new anisotropic effects. We present a theoretical and experimental treatment involving these three specific directions. We apply the theory to analyse SANS and SANSPOL experiments with magnetic colloids. Locally ordered structures formed by magnetic particles are approximated by oriented cylinders and used to explain the different scattering patterns under various external magnetic field and shear conditions. We discuss to what extent SANS and SANSPOL can discriminate between different structure and orientation models