Prolonged memory effect in smectic A phase of a thermotropic liquid crystal material

Abstract

The long-duration memory effect in thermotropic liquid crystal (LC) materials has long been a topic of substantial interest and numerous pioneering works. Although the idea of exploring the memory effect had been started from the nematic (N) phase of LC itself, but due to its very short duration, it was soon shifted to the other LC phases such as ferroelectric LC (FLC) or their derivatives and composites. Therefore, we demonstrate here the prolonged memory effect in a smectic A (SmA) phase of a pristine thermotropic LC material namely 4-octyl-4'-cyanobiphenyl (8CB). The memory effect has also been investigated in the N phase to estimate its duration as compared to the SmA phase. To examine the memory effect, firstly, we measured the dielectric permittivity using the dielectric spectroscopic technique with and without 40V DC biasing. Furthermore, these results have been confirmed by means of optical textures recorded through a polarizing optical microscope. Moreover, we have also observed the removal and retrieval of two stable states by sequent application of heat and DC biasing to examine the cyclability of the LC compound under testing. We anticipate that our results will definitely bridge the gap that occurred in the advancement of emerging futuristic LC-based memory devices.