Revealing the polar nature of a ferroelectric nematic by means of circular alignment

Per Rudquist

doi:10.1038/s41598-021-04028-7

Per Rudquist

Open Access

https://doi.org/10.1038/s41598-021-04028-7

Copy DOI

Abstract

The recent discovery of spontaneously polar nematic liquid crystals—so-called ferroelectric nematics—more than a century after the first discussions about their possible existence—has attracted large interest, both from fundamental scientific and applicational points of view. However, the experimental demonstration of such a phase has, so-far, been non-trivial. Here I present a direct method for the experimental verification of a ferroelectric nematic liquid crystal phase. The method utilizes a single sample cell where the two substrates are linearly and circularly rubbed, respectively, and the ferroelectric nematic phase (NF) is revealed by the orientation of the resulting disclination lines in the cell.

Highlights

The recent discovery of spontaneously polar nematic liquid crystals—so-called ferroelectric nematics— more than a century after the first discussions about their possible existence—has attracted large interest, both from fundamental scientific and applicational points of view
The structure and non-polar symmetry of the N phase is well-known since more than a century and the electrooptic effects of nematic liquid crystals are the basis for the multi-billion dollar liquid crystal display technology
Sebastián et al, by means of second harmonic generation imaging, could draw the conclusion that the local order in the “splay nematic phase” of RM734 is polar on a macroscopic scale and that the splay and polarization modulation period is 5–10 μm

Summary

Introduction

The recent discovery of spontaneously polar nematic liquid crystals—so-called ferroelectric nematics— more than a century after the first discussions about their possible existence—has attracted large interest, both from fundamental scientific and applicational points of view. Mandle et al proposed that the local polar order in the material RM734 was driven by spontaneous splay, (splay nematic phase) which resulted a periodic structure, with alternating direction of splay and polarization[2,3,4].

Results

Conclusion