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arXiv 1503.02014cond-mat.softphysics.chem-ph
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离散液晶中铁电畴的形成:边界条件影响的Monte Carlo研究

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

Tushar Kanti Bose, Jayashree Saha

摘要:

在各向异性介晶流体中实现自发的宏观铁电有序是一个既有基础又有技术意义的课题。最近,我们证明了偶极非手性盘状椭球体系统可以表现出长时间搜索的偶极起源的铁电液晶相。在目前的工作中,广泛的非格子蒙特卡罗模拟被用来调查的静电边界条件的影响下,限制任何全球极化系统的相行为。我们发现,该系统发展强烈的铁电板状畴周期性排列的反铁电的方式。在不同电偶极子强度下的相行为研究中,我们发现畴内存在铁电有序和铁电柱状有序。对于更高的偶极强度,双轴相也得到了类似的周期性阵列的铁电板的反平行极化。我们用Ewald求和法和球面截止法研究了去极化效应。我们提出并比较了两种不同的方法考虑在这个各向异性系统中的去极化效应的结果。它明确表明,作为考虑较长范围的偶极相互作用的结果,域的大小随系统的大小而增加。该系统表现出显着的系统尺寸效应较强的偶极相互作用。结果提供了强有力的证据,新的理解,偶极相互作用确实是足以产生长程铁电各向异性流体秩序。

英文摘要:

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.

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