Field-Induced Stratification of Goethite Particles in Nematic Matrix

Within the continuum theory, the stratification of colloidal goethite particles in a nematic matrix induced by magnetic and gravitational fields has been studied. The case of a magnetically compensated suspension, which is a liquid crystal analogue of an antiferromagnet, is considered. For a twist structure, the spatial distributions of the fields of the director of the liquid crystal medium and the dispersed phase are studied. The distributions of goethite impurity particles over the layer thickness are calculated for different values of the magnetic field. The obtained equations of orientational and magnetic equilibrium of suspensions of goethite particles in a nematic have a general form and, in limiting cases, can be used to describe liquid crystal suspensions of anisometric ferromagnetic particles and carbon nanotubes.