A SMALL-ANGLE NEUTRON-SCATTERING STUDY OF THE FERROSMECTIC PHASE

The ferrosmectic phases are singular swollen lamellar phases whose pec uliarity is to contain colloidal magnetic particles in their layers. A study of these newly invented systems by small angle neutron scatteri ng is presented here. After a prior determination of the appropriate c ontrast conditions performed on the bulk magnetic suspension, we analy se the smectic features of the phases when varying the swelling ratio and the particle concentration. One of their most striking trends is t he evolution of the Bragg and small angle scatterings, which are very different from conventional lamellar phases. We conclude from these re sults that the usual Helfrich repulsion related to the membrane fluctu ations might be modified here by another stabilizing effect due to the presence of the particles.