Electric field induced transient effects in a nematic liquid crystal in the presence of a stabilizing magnetic field

Abstract

A homeotropically aligned nematic liquid crystal with positive dielectric and diamagnetic anisotropies is subjected to a destabilizing ac electric field (E) in the bend geometry in the presence of a stabilizing magnetic field (B). When the applied voltage (V) is gradually increased at a given frequency, the distortion that results above a threshold (VIh) is spatially periodic with the wavevector depending on the electric frequency f. Sudden application of a voltage step, Vs higher than Vth causes a temporal evolution of the director field, which finally attains the homogeneously distorted (HD) state; the nature of temporal evolution depends on Vs. If Vs is slightly higher than Vth, the transient deformation is periodic and the wavevector of periodicity depends on f. When V, is high enough, the transition to HD occurs via a turbulent state.