Unavoidable multilevel biaxial symmetry breaking in chiral hybrid liquid crystals

Journal Article · Thu Apr 10 00:00:00 EDT 2025 · Physical Review. E

DOI:https://doi.org/10.1103/PhysRevE.111.045410· OSTI ID:3018608

Wu, Jin-Sheng ^[1]; Torres Lázaro, Marina ^[2]; Ghosh, Souvik ^[1]; Mundoor, Haridas ^[1]; Wensink, Henricus H. ^[2]; Smalyukh, Ivan I. ^[3]

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1. Univ. of Colorado, Boulder, CO (United States)
2. Centre National de la Recherche Scientifique (CNRS), Orsay (France). Laboratoire de Physique des Solides; Univ. Paris-Saclay, Orsay (France)
3. Univ. of Colorado, Boulder, CO (United States); Hiroshima Univ. (Japan); Univ. of Colorado, Boulder, CO (United States). Renewable and Sustainable Energy Institute (RSEI)

Chiral nematic or cholesteric liquid crystals (LCs) are fluid mesophases with long-ranged orientational order featuring a quasilayered periodicity imparted by a helical director configuration but lacking long-range positional order. Doping molecular cholesteric LCs with strongly anisotropic uniaxial colloidal particles adds another level of complexity because of the interplay between weak surface-anchoring boundary conditions and bulk-based elastic distortions near the particle-LC interface. Using cylindrical colloidal disks and rods with different geometric shapes and surface conditions, we demonstrate that these colloidal inclusions generically exhibit biaxial orientational probability distributions which may impart anomalously strong local biaxiality onto the hybrid cholesteric LC structure. Unlike nonchiral hybrid molecular-colloidal LCs, where biaxial order emerges only at critical colloid volume fractions exceeding some uniaxial-biaxial transition value, the orientational probability of the colloidal inclusions immersed in chiral nematic hosts is unambiguously biaxial even at infinite dilution. We demonstrate that the colloids induce local biaxial perturbations within the molecular orientational order of the LC host medium which strongly enhances the weak but native biaxial order of chiral nematic LC induced by the chiral symmetry breaking of the director field. With the help of analytical modeling and computer simulations based on the Landau–de Gennes free energy of the host LC around the colloids, we rationalize the observed multilevel biaxial order and conclude that it is not only unavoidable but also strongly enhanced compared to both achiral hybrid LCs and purely molecular cholesteric LCs.

• Research Organization: Univ. of Colorado, Boulder, CO (United States)
• Sponsoring Organization: French National Research Agency (ANR); National Science Foundation; USDOE Office of Science (SC), Basic Energy Sciences (BES). Materials Sciences & Engineering Division (MSE)
• Grant/Contract Number: SC0019293
• Other Award/Contract Number: ANR-19-CE30-0024; PHY-1748958
• OSTI ID: 3018608
• Alternate ID(s): OSTI ID: 2554098
• Journal Information: Physical Review. E, Journal Name: Physical Review. E Journal Issue: 4 Vol. 111; ISSN 2470-0053; ISSN 2470-0045
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English

Related Subjects

biaxial liquid crystals
chiral symmetry
chirality
cholesteric liquid crystals
liquid crystals
order parameters