Theory of two- and three-dimensional bent-core mesophases

Ferrielectricity in smectic-C^{*} dechiralization-line lattices

Recent experiments probing a new ferroelectric liquid crystal (CLF08) confined in cells with planar alignment have shown dielectric and optic anomalies suggesting the onset of ferrielectric ordering within the surface lattice of dechiralization lines. We present a phenomenological theory describing the corresponding phase transition sequence SmA→SmC^{*}→Ferri. Phase diagrams and thermodynamic, dielectric, and optic properties are worked out and compared with experiments. The anomalies are related to the predicted tristability of the experimental cells under applied electric field. The order parameters of Landau theory are reinterpreted in terms of line positions, allowing description of the entrance and exit line behavior, and yielding the prediction and identification of new limit phases within a nonconventional Landau approach.

Modulated structures in bent-core liquid crystals: two faces of one phase

The Landau-de Gennes type continuous model is used to describe the 2D modulated structures made of bent-core liquid crystals. It is shown that modulation is a direct consequence of the chiral symmetry breaking. Structures with synclinic and anticlinic layer tilt are found to coexist in the polarization modulated and layer undulated (PM-LU) liquid crystal phase. The synclinic PM-LU structure corresponds to the columnar B(1RevTilted) phase. Experimentally obtained electron density maps are included, which support theoretical findings.