Photopatterned topological structures in ferroelectric nematic liquid crystals

Ferroelectric nematic liquid crystal (NF) is a novel state of matter discovered in very recent years, that exhibits simultaneously high fluidity and ferroelectricity. The polar nature of its order parameter has significant impact on topological defects. Combined with designable photopatterned alignment, various electric polarization topologies beyond solid ferroelectric materials are expected to be achieved and controlled in NF, leading to promising research value in condensed matter physics and electro-optical devices. Here, we investigated the NF phase under confinement of flat surfaces with patterned director of topological defects. These director patterns based on azo-dyes are non-polar for the NF. Our results show that the polar orientation orders of NF including the polar domains and the layout of domain walls are significantly affected by the designed patterns and the confinements. Domain walls could follow the local orientation and emerge with relatively regular arrangements. Different polarization topologies can be observed around defect’s core, and be tuned by surface confinement and defects design. These structures are consequences of electrostatics, elastic energy, surface anchoring, and confinement. Our research could inspire the design and construction of the polar orientation orders in NF.