Abstract
Nematic liquid crystalline structures within square wells are studied numerically using both Lebwohl-Lasher lattice semimicroscopic and the Landau-de Gennes mesoscopic approach. At lateral boundary wall strong planar anchoring is enforced. The cell thicknesshalong thezCartesian coordinate is assumed to be smaller than the characteristic square well sizeR. Using semimicroscopic modelling we restrict to effectively two-dimensional systems which we study in terms of the tensor nematic order parameter. We consider impact of appropriate nanoparticles (NPs) on nematic configuration for cases whereRbecomes comparable to the biaxial order parameter correlation length. In this case a star-like order reconstruction biaxial profile could be formed in absence of NPs. We demonstrate existence of a rich variety of different nematic structures, including topological defects, which are enabled by presence of appropriate NPs.
Highlights
Confined thermotropic liquid crystals (LCs) are of constant interest for years [1,2,3]
Using semimicroscopic modelling we restrict to effectively two-dimensional systems which we study in terms of the tensor nematic order parameter
Sudden drop of ⟨Sz2⟩xy value at critical temperature corresponding to kBTc/J ∼ 1.24 reveals In Figure 3(a) we isotropic-nematic phase transition. plot ⟨β2⟩xz as a function of k = z/a0 in the cells characterized by L = 40 and L = 20
Summary
Confined thermotropic liquid crystals (LCs) are of constant interest for years [1,2,3] Due to their softness, liquid character, optical anisotropy, and rich variety of different phases and structures, they are interesting both from applicational and fundamental perspective [1, 4, 5]. Uniaxial bulk nematic phase represents the simplest LC configuration exhibiting only long range orientational ordering It is typically reached on lowering temperature from isotropic (ordinary liquid) phase via 1st order continuous symmetry breaking phase transition [1, 9, 10]. Typical OR structure mediating two competing regions exhibiting contradicting positive uniaxial ordering consists of a sheet possessing negative uniaxiality lying in between This sheet is further enclosed by two sheets possessing maximal biaxiality.
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