Reflectivity and off-specular neutron scattering from ferrofluid

Near surface properties of ferrofluid (FF) are studied by means of the neut ron reflectivity and off-specular scattering measured in zero magnetic held , and in a field applied within the surface plane, both perpendicular and p arallel to the incoming beam direction. It is found that low magnetic field s substantially perturb the free FF surface which results in dramatic chang es in specular reflection and the off-specular scattering. This phenomena m ay be attributed to the field-induced anisotropy in the particle density co rrelation function. The anisotropy is found to be much less pronounced at t he interface between FF and the silicon wafer. (C) 2000 Elsevier Science B. V. All rights reserved.