2 research outputs found
Critical splay fluctuations and colossal flexoelectric effect above non-polar to polar nematic phase transition
The recent discovery of nematic liquid crystals with polar order
(ferroelectric nematic) has created immense interest. Despite intensive
research, several physical properties of this liquid crystal are yet to be
investigated and understood. Here, we report experimental studies on the
birefringence and exoelectric coefficient of a polar nematic (NF) liquid
crystal. Our experiments directly reveal that the splay fluctuations influence
the birefringence several degrees above the nonpolar (N) to polar-nematic (NF)
phase transition temperature and the heat capacity exponent obtained from the
tilt angle fluctuations is close to the value reported in adiabatic scanning
calorimetry measurements. The flexoelectric coefficient of the nonpolar nematic
phase shows a power-law dependence on temperature. Our results demonstrate a
strong coupling of splay fluctuations with electric polarization that reduces
the splay elastic constant and consequently enhances the flexoelectric
coefficient. These results are important for forthcoming applications as well
as for understanding all pretransitional effects in ferroelectric nematic
liquid crystals.Comment: 5 pages and 4 figure