Bistable Defect Structures In Blue Phase Devices

Tiribocchi, Adriano; Gonnella, Giuseppe; Marenduzzo, Davide; Orlandini, Enzo; Salvadore, Francesco

doi:10.1103/physrevlett.107.237803

Cited by 29 publications

(28 citation statements)

References 25 publications

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“…The dynamic equations for the concentration of the active material and the polarization, which fixes the average orientation of the active component, are derived from a proper free-energy functional and supplemented with the Navier-Stokes equations for the whole fluid in the incompressible limit. These equations are numerically solved by using a hybrid lattice Boltzmann method [17,28,29,30,31,32].…”

Section: Introductionmentioning

confidence: 99%

Morphology and flow patterns in highly asymmetric active emulsions

Negro

Carenza

Digregorio

et al. 2018

Physica A: Statistical Mechanics and its Applications

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We investigate numerically, by a hybrid lattice Boltzmann method, the morphology and the dynamics of an emulsion made of a polar active gel, contractile or extensile, and an isotropic passive fluid.We focus on the case of a highly off-symmetric ratio between the active and passive components.In absence of any activity we observe an hexatic-ordered droplets phase, with some defects in the layout. We study how the morphology of the system is affected by activity both in the contractile and extensile case. In the extensile case a small amount of activity favors the elimination of defects in the array of droplets, while at higher activities, first aster-like rotating droplets appear, and then a disordered pattern occurs. In the contractile case, at sufficiently high values of activity, elongated structures are formed. Energy and enstrophy behavior mark the transitions between the different regimes.

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Section: Introductionmentioning

confidence: 99%

Morphology and flow patterns in highly asymmetric active emulsions

Negro

Carenza

Digregorio

et al. 2018

Physica A: Statistical Mechanics and its Applications

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“…The most relevant phases from the practical point of view are BPI and BPII. The structure of these two phases, is constituted by an intricate double twist cylinder structure6 that is arranged in distinctive cubic lattices78910. This cubic structure can be considered as a highly ordered isotropic medium.…”

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confidence: 99%

Monodomain Blue Phase Liquid Crystal Layers for Phase Modulation

Otón

Netter

Nakano

et al. 2017

Sci Rep

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Liquid crystal “Blue Phases” (BP) have evolved, in the last years, from a scientific curiosity to emerging materials for new photonic and display applications. They possess attractive features over standard nematic liquid crystals, like submillisecond switching times and polarization- independent optical response. However, BPs still present a number of technical issues that prevent their use in practical applications: their phases are only found in limited temperature ranges, thus requiring stabilization of the layers; stabilized BP layers are inhomogeneous and not uniformly oriented, which worsen the optical performance of the devices. It would be essential for practical uses to obtain perfectly aligned and oriented monodomain BP layers, where the alignment and orientation of the cubic lattice are organized in a single 3D structure. In this work we have obtained virtually perfect monodomain BP layers and used them in devices for polarization independent phase modulation. We demonstrate that, under applied voltage, well aligned and oriented layers generate smoother and higher values of the phase shift than inhomogeneous layers, while preserving polarization independency. All BP devices were successfully stabilized in BPI phase, maintaining the layer monodomain homogeneity at room temperature, covering the entire area of the devices with a unique BP phase.

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“…This setup is usually referred as inverted cholesteric emulsion [7,17,31] to be distinguished from a direct emulsion, where a liquid crystal droplet is immersed in an isotropic fluid. The hydrodynamics of such system can be described by using an extended version of the Beris-Edwards theory [28] for chiral fluids, already adopted in previous works on liquid crystals [32][33][34][35]. Here we briefly recap the model.…”

Section: Model and Methodsmentioning

confidence: 99%

Rheology of an Inverted Cholesteric Droplet under Shear Flow

Fadda

Gonnella

Lamura

et al. 2018

Fluids

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Abstract:The dynamics of a quasi two-dimensional isotropic droplet in a cholesteric liquid crystal medium under symmetric shear flow is studied by lattice Boltzmann simulations. We consider a geometry in which the flow direction is along the axis of the cholesteric, as this setup exhibits a significant viscoelastic response to external stress. We find that the dynamics depends on the magnitude of the shear rate, the anchoring strength of the liquid crystal at the droplet interface and the chirality. While low shear rate and weak interface anchoring the system shows a non-Newtonian behavior, a Newtonian-like response is observed at high shear rate and strong interface anchoring. This is investigated both by estimating the secondary flow profile, namely a flow emerging along the out-of-plane direction (absent in fully-Newtonian fluids, such as water) and by monitoring defect formation and dynamics, which significantly alter the rheological response of the system.

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Bistable Defect Structures In Blue Phase Devices

Cited by 29 publications

References 25 publications

Morphology and flow patterns in highly asymmetric active emulsions

Morphology and flow patterns in highly asymmetric active emulsions

Monodomain Blue Phase Liquid Crystal Layers for Phase Modulation

Rheology of an Inverted Cholesteric Droplet under Shear Flow

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