Ferroelectric domain formation in discotic liquid crystals : Monte Carlo study on the influence of boundary conditions

TL;DR

This study uses Monte Carlo simulations to explore how boundary conditions affect ferroelectric domain formation in discotic liquid crystals, revealing the emergence of ferroelectric slabs and the impact of dipole strength and system size.

Contribution

It demonstrates that dipolar interactions alone can induce long-range ferroelectric order in anisotropic fluids under specific boundary conditions.

Findings

Formation of ferroelectric slablike domains with antiferroelectric arrangement.

Existence of ferroelectric nematic and columnar phases within domains.

Domain size increases with system size due to long-range dipolar interactions.

Abstract

The realization of a spontaneous macroscopic ferroelectric order in fluids of anisotropic mesogens is a topic of both fundamental and technological interest. Recently, we demonstrated that a system of dipolar achiral disklike ellipsoids can exhibit long-searched ferroelectric liquid crystalline phases of dipolar origin. In the present work, extensive off-lattice Monte Carlo simulations are used to investigate the phase behavior of the system under the influences of the electrostatic boundary conditions that restrict any global polarization. We find that the system develops strongly ferroelectric slablike domains periodically arranged in an antiferroelectric fashion. Exploring the phase behavior at different dipole strengths, we find existence of the ferroelectric nematic and ferroelectric columnar order inside the domains. For higher dipole strengths, a biaxial phase is also obtained with a similar periodic array of ferroelectric slabs of antiparallel polarizations. We have studied the depolarizing effects by using both the Ewald summation and the spherical cut-off techniques. We present and compare the results of the two different approaches of considering the depolarizing effects in this anisotropic system. It is explicitly shown that the domain size increases with the system size as a result of considering longer range of dipolar interactions. The system exhibits pronounced system size effects for stronger dipolar interactions. The results provide strong evidence to the novel understanding that the dipolar interactions are indeed sufficient to produce long range ferroelectric order in anisotropic fluids.