Hybrid Topological Defects in Ferroelectric Nematic Fluids

TL;DR

This study experimentally and numerically demonstrates the formation and transformation of hybrid topological defects in ferroelectric nematic liquid crystals during phase transitions, validating theoretical predictions.

Contribution

It provides the first direct experimental observation of hybrid topological defects in ferroelectric nematics, linking surface anchoring to defect evolution across phase transitions.

Findings

Disclinations evolve into complex hybrid states.

Surface anchoring controls defect configurations.

Hybrid defects include domain walls, monopoles, and boojums.

Abstract

Field theories predict that phase transitions sequentially breaking continuous and discrete symmetries can generate hybrid topological structures in which defects of different dimensionalities merge. We report experimental and numerical studies of hybrid defects in ferroelectric nematic liquid crystals, which undergo a cascaded transition from isotropic liquid to a high-symmetry apolar, and then to a low-symmetry polar nematic phase. By imposing surface anchoring to preset disclination configurations, we directly track the transformation of topological defects across the transition. We show that simple disclinations reproducibly evolve into complex hybrid states, including domain walls terminated by surface disclinations, domain walls decorated with monopoles, and merons-mediated boojums and monopoles. These results provide definitive experimental validation of hybrid defects in a soft matter system and establish ferroelectric nematics as a model platform for exploring and engineering polar defect structures.