Molecular Reorientation Process and Non-Linear Polarization Reversal Current in Helicoidal Ferroelectric Liquid Crystal DOBAMBC

Molecular reorientation processes and polarization reversal current in ferroelectric liquid crystals are studied for a 10 μm thick sample of DOBAMBC by applying symmetric (−5 V–0 V−+5 V) and asymmetric [(+ or − ) 10 V–0 V] triangular wave pulses at 0.5 Hz frequency. For symmetric pulse a single peak of polarization reversal and for asymmetric pulse two peaks near 0 V region which is due to helix winding and unwinding processes are observed. The single peak of polarization reversal current for symmetric triangular pulse occurs due to combined effect of helix winding and unwinding processes under the influence of depolarization field. The presence of depolarization field during switching amongst uniform states also results in a clearly noticeable non-linear current response of the ferroelectric liquid crystal cell on the application of linearly varying symmetric triangular pulse.