I. Potočová

The structural transitions in the thermotropic ferronematics

The structural transitions in thermotropic ferronematic, i.e. nematic liquid crystal (8CB) doped with fine magnetic particles (d~10 nm), exposed to combined electric and magnetic fields, were studied within the Burylov and Raikhers theory. Using the found formulas for the threshold fields of studied transitions and their values obtained by the capacitance measurements, the anchoring energy W of liquid crystal molecules on the magnetic particles surfaces, as well as parameter ω, determining the type of anchoring, were calculated. The calculated values indicated the presence of soft, or some intermediate state between soft and rigid anchoring, in studied ferronematic. These results are in agreement with the Burylov and Raikhers theory of thermotropic ferronematics.

Light Induced Structuralization in Magnetic Fluids with Negative Soret Constant

The structuralization of the colloidal particles concentration in illuminated magnetic fluids with negative Soret constant was investigated. A theoretical explanation of the phenomenon, based on the study of the thermodiffusion process in colloidal fluids, was made. The development of the structuralization after the intensity of the illumination reaches some critical value was both simulated and observed experimentally.