Spontaneous helielectric nematic liquid crystals: Electric analog to helimagnets

Abstract

Recently, a type of ferroelectric nematic fluid has been discovered in liquid crystals in which the molecular polar nature at molecule level is amplified to macroscopic scales through a ferroelectric packing of rod-shaped molecules. Here, we report on the experimental proof of a polar chiral liquid matter state, dubbed helielectric nematic, stabilized by the local polar ordering coupled to the chiral helicity. This helielectric structure carries the polar vector rotating helically, analogous to the magnetic counterpart of helimagnet. The helielectric state can be retained down to room temperature and demonstrates gigantic dielectric and nonlinear optical responses. This matter state opens a new chapter for developing the diverse polar liquid crystal devices.

A new order of liquids: polar order in nematic liquid crystals

“…3 Structural variants of RM734 temperatures (1C) are on cooling from the isotropic liquid. 5,18,20,28 A green and red arrows indicate increased and decreased T NF-N relative to the parent material, respectively, while a black dash indicates the absence of the N F phase.…”

“…28 Imrie et al also reported a number of RM734 derivatives with alternate lateral groups, including the ( S )-2-methylbutoxy group which leads to the chiral N F phase, 20 with this material also being reported independently by others. 18 Again, the increased steric bulk of these lateral groups depresses T NF-N when compared to the parent material. Aya et al synthesised materials in which the lateral unit is positioned to the central phenyl ring, all of which generate the N F phase with a modest reduction in T NF-N .…”

“…Notably, the polar analogue of the chiral nematic phase has very recently been discovered. [17][18][19][20][21] Lastly, one further example of nematic polymorphism must be considered. In 2011 the twist-bend nematic phase was discovered, having being predicted some ten years earlier by Ivan Dozov, marking the first new nematic phase type discovered in over half a century.…”

A New Order of Liquids: Polar Order in Nematic Liquid Crystals

“…28 Imrie et al also reported a number of RM734 derivatives with alternate lateral groups, including the (S)-2-methylbutoxy group which leads to the chiral NF phase, 20 with this material also being reported independently by others. 18 Again, the increased steric bulk of these lateral groups depresses TN F -N when compared to the parent material. Aya et al synthesised materials in which the lateral unit is positioned to the central phenyl ring, all of which generate the NF phase with a modest reduction in TN F -N. 28 Use of azo or nmethylamide linking units eliminates the NF phase entirely, and also the nematic phase in the case of the amide.…”

“…Figure 3:Structural Variants of RM734 temperatures (°C) are on cooling from the isotropic liquid 5,18,20,28. A green and red arrows indicate increased and decreased TNF-N relative to the parent material, respectively, while a black dash indicates the absence of the NF phase.…”