Thermal Fluctuation Effects in Ferroelectric Liquid-Crystal PolarizationReversal: Light Scattering from a Transient Domain-Wall Foam

摘要

Thermal orientation fluctuations of the director field during electric-field-induced polarization reversal ferroelectric liquid crystals lead to the nondeterministic formation of a transient domain-wall foam that strongly scatters light. This foam comprises domains of molecules that have reoriented locally in the same sense on the smectic-C tilt cone and are separated from one another by 2 pi inversion walls. The dynamics of formation and the subsequent annealing of the foam have been probed using laser light scattering. Anisotropic coarsening of the foam, which is accounted for by including electrostatic (space-charge) interactions in the theoretical description of the ferroelectric liquid crystal, results in a striking pattern of elongated stripes. Stroboscopic microscopy reveals that these stripes are in general rotated from the smectic-layer planes in a chiral sense, the sense of the rotation depending on the sign of dE/dt.