To the theory of structural phase transitions in ferronematics

The Frederiks effect and corrugations of a flat free surface of ferronemati cs has been studied. The characteristic time of ferroparticle reorientation relatively to nematic solvent is supposed to be very large. Our results sh ow that the Frederiks transition may occur due to space separation of ferro particles with different orientations of their magnetic moments in an homog eneous external magnetic field. The deformation of a free surface of such f erronematics, in contrast to the ordinary magnetic liquids, may occur even in the absence of an external field. We have calculated the critical ferron ematics magnetization, corresponding to this phenomenon and estimated the e quilibrium wave number of these deformations. (C) 1999 Elsevier Science B.V . Ail rights reserved.