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Microscale structural fluctuations at the melting phase transition of strongly confined achiral and chiral nematics

J. Pišljar1,2,*, A. Nych3,1, U. Ognysta3, S. Kralj4,1, and I. Muševič1,2

  • 1Condensed Matter Department, J. Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia
  • 2Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000 Ljubljana, Slovenia
  • 3Department of Molecular Photoelectronics, Institute of Physics, Nauky prospect 46, Kyiv 03680, Ukraine
  • 4Department of Physics, Faculty of Natural Sciences and Mathematics, University of Maribor, Koroška 160, 2000 Maribor, Slovenia

  • *Contact author: jaka.pisljar@ijs.si
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Phys. Rev. E 111, 045415 – Published 15 April, 2025

DOI: https://doi.org/10.1103/PhysRevE.111.045415

Abstract

We report on direct microscopic observations of thermally driven fluctuating dynamics in a narrow temperature region between the isotropic and low-temperature phases in achiral, chiral, and strongly chiral (blue phase) liquid crystal materials. We observe the dynamics in samples strongly confined between two glass surfaces which act as disordering surfaces at thicknesses above the critical confinement thickness below which the phase transition is gradual. In achiral and long-pitch chiral materials the fluctuating appears as formation and disappearance of small structureless nematic domains, whereas in strongly chiral materials, which exhibit blue phase I at larger thicknesses, these fluctuations are real-time formation and annihilation of topologically nontrivial nematic half-skyrmions. We study the dynamics of these fluctuations and present a simple model that explains how such dynamics is possible in ultraconfined systems.

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Phys. Rev. E 111, 045415– Published 15 April, 2025
  • Received 30 October 2024
  • Revised 6 March 2025
  • Accepted 24 March 2025
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Published by the American Physical Society under the terms of the Creative Commons Attribution 4.0 International 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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