Nature of ferronematic alignment in a magnetic field

Ferronematics are stable liquid crystal dispersions with high magnetic susceptibility. Although predicted many years ago (1970), they have been synthesized only recently. The experimental determination of the Fréedericksz transition critical field in ferronematics contradicts the earlier [Brochard and de Gennes, J. Phys. (Paris) 31, 691 (1970)] assumption of strong anchoring between liquid crystal molecules and magnetic grains. Here an explanation consistent with the experimental results of the coupling between liquid crystalline and magnetic degrees of freedom is given. We explain that this coupling is due to steric interactions between anisometric liquid crystal micelles and ferroparticle clusters.