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In contrast to the predictions of the standard theory of electroconvection (EC), our experiments showed that the action of superposed ac and dc voltages rather inhibits pattern formation than favours the emergence of instabilities; the…

Soft Condensed Matter · Physics 2014-09-04 Peter Salamon , Nandor Eber , Balazs Fekete , Agnes Buka

The effect of superposed dc and ac applied voltages on two types of spatially periodic instabilities in nematic liquid crystals, flexoelectric domains (FD) and electroconvection (EC), was studied. The onset characteristics, threshold…

Soft Condensed Matter · Physics 2016-09-15 Nándor Éber , Péter Salamon , Balázs András Fekete , Ridvan Karapinar , Alexei Krekhov , Ágnes Buka

Pattern forming instabilities induced by ultralow frequency sinusoidal voltages were studied in a rod-like nematic liquid crystal by microscopic observations and simultaneous electric current measurements. Two pattern morphologies,…

Soft Condensed Matter · Physics 2014-09-04 Peter Salamon , Nandor Eber , Alexei Krekhov , Agnes Buka

Two kinds of electroconvection (EC) patterns in an ether-bridged bent-core nematic liquid crystal material (BCN), which appear in different frequency ranges, are examined and compared in this paper. One is a longitudinal pattern with the…

Soft Condensed Matter · Physics 2014-12-02 Ying Xiang , Yi-Kun Liu , Ágnes Buka , Nándor Éber , Zhi-Yong Zhang , Ming-Ya Xu , Everett Wang

Patterns forming spontaneously in extended, three-dimensional, dissipative systems are likely to excite several homogeneous soft modes ($\approx$ hydrodynamic modes) of the underlying physical system, much more than quasi one- and…

Pattern Formation and Solitons · Physics 2009-10-31 Axel G. Rossberg

Electro-hydrodynamic phenomena in liquid crystals constitute an old but still very active research area. The reason is that these phenomena play the key role in various applications of liquid crystals and due to the general interest of…

Soft Condensed Matter · Physics 2024-03-14 E. S. Pikina , A. R. Muratov , E. I. Kats , V. V. Lebedev

Suspended microparticles subjected to AC electrical fields collectively organize into band patterns perpendicular to the field direction. The bands further develop into zigzag shaped patterns, in which the particles are observed to…

Soft Condensed Matter · Physics 2022-02-16 Florian Katzmeier , Bernhard Altaner , Jonathan List , Ulrich Gerland , Friedrich C. Simmel

We report on the early time ordering in a nematic liquid crystal subjected to a sudden change in external ac electric field. We compare time evolution for two different initial states of electroconvection. Electroconvection is a highly…

Soft Condensed Matter · Physics 2007-05-23 Denis Funfschilling , Michael Dennin

Field-induced assembly of colloidal particles into structures of desired configurations is extremely relevant from the viewpoint of producing field-assembled micro-swimmers and reconfigurable smart materials. However, the behaviour of…

Soft Condensed Matter · Physics 2024-10-23 Indira Barros , Sayanth Ramachandran , Indrani Chakraborty

We present in this paper a detailed analysis of the flexoelectric instability of a planar nematic layer in the presence of an alternating electric field (frequency $\omega$), which leads to stripe patterns (flexodomains) in the plane of the…

Soft Condensed Matter · Physics 2015-05-27 Alexei Krekhov , Werner Pesch , Agnes Buka

Novel behavior in electroconvection (EC) has been detected in nematic liquid crystals (NLCs) under the condition of comparable timescales of the director relaxation and the period of the driving ac voltage. The studied NLCs exhibit standard…

Soft Condensed Matter · Physics 2009-11-13 Tibor Toth-Katona , Nandor Eber , Agnes Buka , Alexei Krekhov

We investigated the electrical properties of the liquid crystal compound, known as an RM734, exhibiting a ferroelectric nematic phase. The influence of alternating (AC) and direct (DC) current electric fields on the switching process of the…

Soft Condensed Matter · Physics 2025-03-04 Mateusz Mrukiewicz , Paweł Perkowski , Jakub Karcz , Przemysław Kula

We investigate a number of complex patterns driven by the electro-convection instability in a planarly aligned layer of a nematic liquid crystal. They are traced back to various secondary instabilities of the ideal roll patterns bifurcating…

Soft Condensed Matter · Physics 2015-12-23 Alexei Krekhov , Bernd Dressel , Werner Pesch , Vladimir Delev , Eduard Batyrshin

For the first time the electrohydrodynamic convection (EHC) of nematic liquid crystals is studied via fully nonlinear simulation. As a system of rich pattern-formation the EHC is mostly studied with negative nematic liquid crystals…

Soft Condensed Matter · Physics 2016-12-28 Kuang-Wu Lee , Thorsten Pöschel

Systems involving nematic liquid crystals subjected to magnetic fields or electric fields are modeled using the Oseen-Frank macroscopic continuum theory, and general criteria are developed to assess the local stability of equilibrium…

Soft Condensed Matter · Physics 2021-03-15 Eugene C. Gartland,

We present nonlinear dynamic equations for nematic and smectic $A$ liquid crystals in the presence of an alternating electric field and explain their derivation in detail. The local electric field acting in any liquid-crystalline system is…

Soft Condensed Matter · Physics 2023-06-30 E. S. Pikina , E. I. Kats , A. R. Muratov , V. V. Lebedev

Regulation of topological structures and pattern formation is attracting wide interest in the field of condensed matter. Liquid crystals (LCs) represent soft matter with a remarkable combination of fluidity and anisotropic properties.…

Soft Condensed Matter · Physics 2025-12-09 Natalia Podoliak , Lubor Lejcek , Martin Cigl , Vladimira Novotna

When the interface between a dielectric and a conducting liquid is excited by an oscillatory electric field, electrostatic Faraday waves can be induced. Here, we study the response of the interface to an AC electric field, which is…

Fluid Dynamics · Physics 2022-04-08 Sebastian Dehe , Maximilian Hartmann , Aditya Bandopadhyay , Steffen Hardt

Nematic drops suspended in the isotropic phase of the same substance were subjected to alternating electrical fields of varying frequency. The system was carefully kept in the isotropic-nematic coexistance region, which was broadened due to…

Soft Condensed Matter · Physics 2009-03-27 Günter K. Auernhammer , Jinyu Zhao , Beate Ullrich , Doris Vollmer

We report experimental and theoretical results on the flexoelectric instability and crossover between flexoelectric domains and electroconvection in a hybrid aligned nematic MBBA under d.c. voltage. At threshold a spatially periodic…

Pattern Formation and Solitons · Physics 2007-05-23 V. A. Delev , A. P. Krekhov , L. Kramer
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