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Updated: Mar 2, 2026

High-Contrast and Fast Photorheological Switching of a Twist-Bend Nematic Liquid Crystal
Published on: October 31, 2019
Twisting with a twist: supramolecular helix fluctuations in chiral nematics
Henricus Herman Wensink1, Claudia Ferreiro-Córdova
1Laboratoire de Physique des Solides - UMR 8502, CNRS, Université Paris-Sud, Université Paris-Saclay, 91405, Orsay cedex, France. rik.wensink@u-psud.fr.
Abstract:
Most theoretical descriptions of lyotropic cholesteric liquid crystals to date focus on homogeneous systems in which the rod concentration, as opposed to the rod orientation, is uniform. In this work, we build upon the Onsager-Straley theory for twisted nematics and study the effect of weak concentration gradients, generated by some external potential, on the cholesteric twist. We apply our theory to chiral nematics of nanohelices in which the supramolecular helix sense is known to spontaneously change sign upon variation of particle concentration, passing through a so-called compensation point at which the mesoscopic twist vanishes. We show that the imposed field offers exquisite control of the handedness and magnitude of the helicoidal director field, even at weak field strengths. Within the same framework we also quantify the director fluctuation spectrum and find evidence for a correlation length diverging at the compensation point.
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