Polarization reversal and hysteresis loops of anti-ferroelectric liquid crystal, MHPOBC

Abstract

Temperature dependence and field impressing rate, dE/dt, dependence of polarization switching phenomena and field-induced phase transition in an antiferroelectric liquid crystal (MHPOBC) were investigated by simultaneous measurement of polarization reversal current and optical transmittance. The dE/dt dependence of hysteresis loops suggests that two phases spatially coexist; such as, ferroelectric and antiferroelectric phases or ferroelectric and ferrielectric. With decreasing dE/dt, the coercive field of hysteresis loop in the ferroelectric phase continues to decrease from a positive value to zero and then becomes negative. Ionic current and accumulation of free charges near the electrodes are possible to be the origin of the phenomenon.