Phase behavior of magnetic nanoparticles dispersions in bulk and confined geometries

Dispersions of magnetic nanoparticles (ferrofluids) have been for a long time taken as examples of dipolar fluids. Theoretical papers conclude now that an important parameter is the ratio of the anisotropic attractions (dipolar ones) to the isotropic attractions (Van der Waals ones). It is confirmed by the recent experimental results concerning the behavior of small magnetic particles in bulk or confined 2D geometries.