Dielectric Hysteresis, Relaxation Dynamics, and Non-volatile Memory Effect in Carbon Nanotube Dispersed Liquid Crystal

Abstract

The self-organizing properties of nematic liquid crystals (LC) can be used to template carbon nanotubes (CNTs) on a macroscopic dimension. The nematic director field, coupled to the dispersed CNT long-axis, enables controlled director reorientation using well-established methods of LC alignment techniques, such as patterned-electrode-surface, electric fields, and magnetic fields. Electric field induced director rotation of a nematic LC+CNT system is of potential interests due to its possible applications as a nano electromechanical system. The relaxation mechanism for a LC+CNT composite, on the removal of the applied field, reveals the intrinsic dynamics of this anisotropic system. Dielectric hysteresis and temperature dependence of the dielectric constant coherently shows the ferroelectric-type behavior of the LC+CNT system in the nematic phase. The strong surface anchoring of LC molecules on CNT walls results in forming local isolated pseudo-nematic domains in the isotropic phase. These domains, being anisotropic, respond to external fields, but, do not relax back to the original state on switching of the field off, showing non-volatile memory effect.