Phase Diagram of Confined Antiferroelectric Liquid Crystals in an Electric Field

Abstract

We study the electric-field-induced transitions in antiferroelectric liquid crystals in a model that takes into account the intralayer elastic distortion, the nearest-neighbor interlayer interaction, the coupling of the spontaneous polarization with the applied field, the dielectric anisotropy, and the surface anchoring. We find that the field-induced phase sequence has a critical dependence on cell thickness. For moderately thin cells (thickness > 0.1 μm) with moderately strong anchoring (surface coupling ∼ 10⁻⁴ J/m²), the system, in departing from the initial anticlinic alignment, first undergoes a continuous Fréederiksz transition, then a first-order surface boundary-layer transition, and finally a first-order or continuous transition to a complete synclinic ordering. Reducing the cell thickness to less than 0.1 μm will make the Fréedericksz transition and even the boundary-layer transition vanish.

Key Words:

• antiferroelectric liquid crystal
• phase diagram