To the theory of structural phase transitions in ferronematics

The Frederiks effect and corrugations of a flat free surface of ferronematics has been studied. The characteristic time of ferroparticle reorientation relatively to nematic solvent is supposed to be very large. Our results show that the Frederiks transition may occur due to space separation of ferroparticles with different orientations of their magnetic moments in an homogeneous external magnetic field. The deformation of a free surface of such ferronematics, in contrast to the ordinary magnetic liquids, may occur even in the absence of an external field. We have calculated the critical ferronematics magnetization, corresponding to this phenomenon and estimated the equilibrium wave number of these deformations.