Stratification of ferroparticles caused by gravitational and magnetic fields in soft ferronematics

Abstract

Abstract In the framework of continuum theory we study the magnetic particles stratification caused by gravitational and magnetic fields in ferronematic, i.e., a highly dispersed suspension of ferroparticles in a nematic liquid crystal. We consider the so-called soft ferronematic, where the coupling energy between the liquid crystal and the particle surfaces is finite, which allows to consider the director and magnetization of the ferronematic as independent variables. We show how under the influence of an external uniform magnetic field due to the segregation effect heavy impurity ferromagnetic particles begin to float up in a lower-density fluid, moving opposite to the gravity field. As an example, several types of suspensions with material parameters corresponding to actually synthesized ferronematics with different ratios between the two competing mechanisms of separation of impurity particles (segregation and gravity) are considered.