Chiral π domain walls and double splay nematic ordering in polar fluids

In this talk, I will present two of our recent findings about ferroelectric nematic liquid crystals. (1) We revealed that π domain walls in polar liquids are composed of twin half-integer surface disclinations that enclose chiral twisted subdomains, and that degenerate geometric configurations of these twin disclinations give rise to Φ4 kinks and anti-kinks, effectively dividing the domain walls into left-handed or right-handed chiral regions. Such hierarchical topological structure is fundamentally distinct from the π walls in solid ferroelectrics that are typically of the Ising type. (2) We demonstrated that doping the polar liquid crystal RM734 with cationic polymers induces the formation of a modulated phase as a complex interplay between flexoelectricity and electrostatic interactions. This modulated phase is antiferroelectric, characterized by alternating splay deformations in two orthogonal directions, oriented at 45° relative to the confining surfaces.