NONLINEAR REPOLARIZATION PROCESSES IN FERROELECTRIC LIQUID-CRYSTAL THIN-FILMS

The dynamics of spontaneous polarization switching of the ferroelectri c smectic C in a variable electric field are examined theoretically a nd experimentally with the help of polarized light scattering. The obs erved effect of quasiresonant scattering both in freely suspended smec tic films and in ordinary electro-optical cells is interpreted within the framework of the nonlinear model of isolated movable kinks in the director orientation distribution, It is shown that the maximum of the scattering intensity at the characteristic frequency of the applied e lectric field disappears at low temperatures and for small thicknesses of the smectic film. The dependence of the ''resonant'' frequency on the electric field amplitude, the proximity to the phase transition te mperature, the film thickness and thickness of the ferroelectric domai ns, and also various material parameters Is found, Estimates are made of such important characteristics as the dielectric anisotropy, viscos ity, and elasticity of the smectic films. The effect of film thickness on the density distribution of the polar anisotropy energy in the fil m and on the corresponding shape of the moving orientation front withi n the film are discussed. (C) 1997 American Institute of Physics.