Umbilical defect dynamics in an inhomogeneous nematic liquid crystal layer

Zambra, Valeska; Clerc, Marcel G.; Barboza, Raouf; Bortolozzo, U.; Residori, Stefania

doi:10.1103/physreve.101.062704

Cited by 8 publications

(4 citation statements)

References 34 publications

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“…1 H ), or at the interface of glass beads, as depicted in Fig. 1 I (cell #2), where molecular deformations are enhanced ( 31 , 41 ). Under the experimental conditions considered here, the winding/unwinding transition is characterized by the emergence of CF1 ( Fig.…”

Section: Resultsmentioning

confidence: 99%

Emergence of disordered branching patterns in confined chiral nematic liquid crystals

Echeverría-Alar

Clerc

Bordeu

2023

Proc. Natl. Acad. Sci. U.S.A.

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Spatial branching processes are ubiquitous in nature, yet the mechanisms that drive their growth may vary significantly from one system to another. In soft matter physics, chiral nematic liquid crystals provide a controlled setting to study the emergence and growth dynamic of disordered branching patterns. Via an appropriate forcing, a cholesteric phase may nucleate in a chiral nematic liquid crystal, which self-organizes into an extended branching pattern. It is known that branching events take place when the rounded tips of cholesteric fingers swell, become unstable, and split into two new cholesteric tips. The origin of this interfacial instability and the mechanisms that drive the large-scale spatial organization of these cholesteric patterns remain unclear. In this work, we investigate experimentally the spatial and temporal organization of thermally driven branching patterns in chiral nematic liquid crystal cells. We describe the observations through a mean-field model and find that chirality is responsible for the creation of fingers, regulates their interactions, and controls the tip-splitting process. Furthermore, we show that the complex dynamics of the cholesteric pattern behaves as a probabilistic process of branching and inhibition of chiral tips that drives the large-scale topological organization. Our theoretical findings are in good agreement with the experimental observations.

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Section: Resultsmentioning

confidence: 99%

Emergence of disordered branching patterns in confined chiral nematic liquid crystals

Echeverría-Alar

Clerc

Bordeu

2023

Proc. Natl. Acad. Sci. U.S.A.

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“…Hence, vortices quickly emerge, as illustrated in inset t 3 . Once established a vortex gas, the vortices are subsequently annihilated by pairs of opposite charges (see insets t 4 , t 5 and t 6 ), generating a coarsening processes characterized by a Power Law [33].…”

Section: Experimental Vortices Nucleationmentioning

confidence: 99%

Vortices Nucleation By Inherent Fluctuations In Nematic Liquid Crystal Cells

Aguilera

Clerc

Zambra

2021

Preprint

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Multistable systems are characterized by exhibiting domain coexistence, where each domain accounts for the different states. In the case of these systems are described by vectorial fields, domains are connected through topological defects. Vortices are one of the most frequent and studied topological defect points. Optical vortices are equally relevant for their fundamental features as beams with topological features and their applications in image processing, telecommunications, optical tweezers, and quantum information. The interaction of light beams with matter vortices in liquid crystal cells is a natural source of optical vortices. The rhythms that govern the emergence of matter vortexes due to fluctuations are not established. Here we investigate the nucleation mechanisms of the matter vortices in liquid crystal cells and establish statistical laws that govern them. Based on a stochastic amplitude equation, the law for the number of nucleated vortices as a function of anisotropy, voltage, and noise level intensity is set. Experimental observations in a nematic liquid crystal cell with homeotropic anchoring and a negative anisotropic dielectric constant under the influence of a transversal electric field show a fair agreement with the theoretical findings.

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“…In thermodynamic equilibrium and homogeneous media, the vortices tend to annihilate by pairs to minimise the free energy of the system. The above dynamics can be modified by means of incorporation of inhomogeneities, which can attract and trap umbilical defects [15,16]. Properly distributed inhomogeneities may permit the formation of topology lattice [15].…”

Section: Introductionmentioning

confidence: 99%

Exotic states of matter in an oscillatory driven liquid crystal cell

Clerc,

Kowalczyk,

Zambra

2020

Preprint

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Matter under different equilibrium conditions of pressure and temperature exhibits different states such as solid, liquid, gas, and plasma. Exotic states of matter, such as Bose-Einstein condensates, superfluidity, chiral magnets, superconductivity, and liquid crystalline blue phases are observed in thermodynamic equilibrium. Rather than being a result of an aggregation of matter, their emergence is due to a change of a topological state of the system. Here we investigate topological states of matter in a system with injection and dissipation of energy. In an experiment involving a liquid crystal cell under the influence of a low-frequency oscillatory electric field, we observe a transition from non-vortex state to a state in which vortices persist. Depending on the period and the type of the forcing, the vortices self-organise forming square lattices, glassy states, and disordered vortex structures. Based on a stochastic amplitude equation, we recognise the origin of the transition as the balance between stochastic creation and deterministic annihilation of vortices. Our results show that the matter maintained out of equilibrium by means of the temporal modulation of parameters can exhibit exotic states.

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Umbilical defect dynamics in an inhomogeneous nematic liquid crystal layer

Cited by 8 publications

References 34 publications

Emergence of disordered branching patterns in confined chiral nematic liquid crystals

Emergence of disordered branching patterns in confined chiral nematic liquid crystals

Vortices Nucleation By Inherent Fluctuations In Nematic Liquid Crystal Cells

Exotic states of matter in an oscillatory driven liquid crystal cell

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