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Fluctuation modes of a twist-bend nematic liquid crystal

Parsouzi, Z.; Shamid, S. M.; Borshch, V.; Challa, P. K.; Baldwin, A. R.; Tamba, M. G.; Welch, C.; Mehl, G. H.; Gleeson, J. T.; Jakli, A.; Lavrentovich, O. D.; Allender, D. W.; Selinger, J. V.; Sprunt, S.

Authors

Z. Parsouzi

A. Jakli

O. D. Lavrentovich

D. W. Allender

J. V. Selinger

S. Sprunt

S. M. Shamid

V. Borshch

P. K. Challa

A. R. Baldwin

M. G. Tamba

C. Welch

J. T. Gleeson

Abstract

We report a dynamic light-scattering study of the fluctuation modes in a thermotropic liquid crystalline mixture of monomer and dimer compounds that exhibits the twist-bend nematic (NTB) phase. The results reveal a spectrum of overdamped fluctuations that includes two nonhydrodynamic modes and one hydrodynamic mode in the N TB phase, and a single nonhydrodynamic mode plus two hydrodynamic modes (the usual nematic optic axis or director fluctuations) in the higher temperature, uniaxial nematic phase. The properties of these fluctuations and the conditions for their observation are comprehensively explained by a Landau-de Gennes expansion of the free-energy density in terms of heliconical director and helical polarization fields that characterize the N TB structure, with the latter serving as the primary order parameter. A "coarse-graining" approximation simplifies the theoretical analysis and enables us to demonstrate quantitative agreement between the calculated and experimentally determined temperature dependence of the mode relaxation rates.

Journal Article Type Article
Publication Date Jun 22, 2016
Journal Physical review x
Electronic ISSN 2160-3308
Publisher American Physical Society
Peer Reviewed Peer Reviewed
Volume 6
Issue 2
Pages 021041-1-021041-16
DOI https://doi.org/10.1103/PhysRevX.6.021041
Keywords Twist-bend nematic
Publisher URL https://journals.aps.org/prx/abstract/10.1103/PhysRevX.6.021041
Additional Information This is a copy of an open access article published in Physical review x, 2016, v.6.

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Published by the American Physical Society under the terms of the Creative Commons Attribution 3.0 License. Further distribution of this work must maintain attribution to the author(s) and the published article’s title, journal citation, and DOI.


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