Effect of the liquid crystal occur environment on the aggregation of magnetic grains in ferronematics

The strain fields produced by nanometre sized particles in liquid crystals are partially cancelled if they aggregate. However, if the particles are too small, and the energy gain is less than kT, where T is the temperature, and k is Boltzmann's constant, they do not aggregate. We show that the aggregation is indeed size dependent by analyzing the temperature dependence of the magnetic susceptibility of a nematic liquid crystal doped with a few % of a commercial ferrofluid.