Electric field response and pre-transitional dynamics of cybotactic clusters in asymmetric bent-core nematics

The recent discovery of the ferroelectric nematic (NF) phase highlights the critical role of cybotactic clustering (Ncyb) in mediating paraelectric-to-ferroelectric transitions. However, the relationship between molecular architecture, Ncyb stability, and pre-transitional dynamics has yet to be reported. This study addresses this issue by investigating the isotropic (I) to cybotactic nematic (Ncyb) phase transition in a hockey-stick-shaped bent-core mesogen (C8CH3Cl) chosen for its distinct structural asymmetry and propensity to form polar nanoclusters. We employed broadband dielectric spectroscopy across the mesomorphic range, complemented by Landau – de Gennes and Maier – Saupe theoretical analysis. Two distinct dielectric relaxation modes are identified in the I and Ncyb phases. Crucially, a convex-shaped anomaly (CSA) was observed in the static permittivity near the I-Ncyb transition, indicating significant pre-transitional fluctuations. These findings provide experimental evidence of CSA at the I-Ncyb transition, linking molecular asymmetry (hockey-stick design) to emergent pre-ferroelectric dynamics via cybotactic clustering.