Article
Physics, Fluids & Plasmas
A. Nych, R. Kravchuk, U. Ognysta, M. Ledney, O. Yaroshchuk
Summary: The study investigates the orientational configurations of thermotropic nematic liquid crystal in cylindrical capillaries with nondegenerated planar surface anchoring. By applying photoaligning coating on the inner wall of the capillary treated with UV light, different twisted structures can be achieved, from axial alignment with zero twist to 180 degrees-twisted configuration. Optical ray tracing calculations reveal the UV light intensity and polarization distribution over the inner capillary surface, providing valuable insights into liquid crystal behavior.
Article
Multidisciplinary Sciences
Xi Chen, Eva Korblova, Matthew A. Glaser, Joseph E. Maclennan, David M. Walba, Noel A. Clark
Summary: Surface interactions can structurally influence the polarization field of a ferroelectric fluid, allowing for the formation of high polarization states without the need for electric field poling. Different treatments can induce various polarization structures at the surface and within the cell, leading to a range of distinct modes of ferroelectric nematic electro-optic responses.
PROCEEDINGS OF THE NATIONAL ACADEMY OF SCIENCES OF THE UNITED STATES OF AMERICA
(2021)
Article
Physics, Fluids & Plasmas
Izabela Sliwa, Pavel V. Maslennikov, Alex V. Zakharov
Summary: This article describes the physical mechanism behind the appearance of traveling and nontraveling distortions in a microsized homogeneously aligned nematic film under the effect of a large electric field. Numerical studies reveal that the director's field may experience a traveling distortion wave in response to the electric field, with the rate of distortion depending on the magnitude of the applied field.
Article
Multidisciplinary Sciences
Runa Koizumi, Dmitry Golovaty, Ali Alqarni, Bing-Xiang Li, Peter J. Sternberg, Oleg D. Lavrentovich
Summary: The morphogenesis of living systems involves unusual topological shape transformations. In this study, a droplet of a nematic liquid crystal changes its equilibrium shape from a simply connected tactoid to a torus. This topological transformation is caused by the interplay of nematic elastic constants, facilitating splay and bend of molecular orientations in tactoids but hindering splay in toroids. This elastic anisotropy mechanism provides insights into topology transformations in morphogenesis and opens possibilities for controlling and transforming the shapes of liquid crystal droplets and related soft materials.
Article
Chemistry, Physical
Semen S. Tenishchev, Ivan M. Tambovtcev, Alexei D. Kiselev, Valery M. Uzdin
Summary: The study discovered that the critical voltage of the Freedericksz transition is proportional to the free twisting wave number for branches with non-vanishing half-turn number. The energy barrier exhibits hysteresis with respect to the electric field dependence, and a first-order electrically driven transition involving out-of-plane director deformations was observed when passing through a first-order saddle point in minimum-energy pathways.
JOURNAL OF MOLECULAR LIQUIDS
(2021)
Article
Chemistry, Multidisciplinary
Mariola Buczkowska, Jedrzej Graczykowski
Summary: Numerical investigation of electric field induced deformations in super-twisted layers of nematic liquid crystals with flexoelectric properties revealed energetically preferred two-dimensional deformations similar to those found in cells twisted by 90 degrees. Two different kinds of periodic deformation were distinguished, with different structures and directions relative to surface anchoring. The evolution of deformations during changes of bias voltage common for all twist angles was recognized and the role of flexoelectric properties was analyzed.
Article
Multidisciplinary Sciences
Ziga Kos, Joern Dunkel
Summary: In this study, the concept of nematic bits (nbits) is introduced in liquid crystals, and it is demonstrated through theory and simulations how single-bit operations can be implemented using electric fields and how universal classical logic gates and generalized logical functions can be realized using nematoelastic interactions.
Article
Physics, Fluids & Plasmas
Izabela Shwa, Pavel Maslennikov, Alex Zakharov
Summary: This article describes the physical mechanisms behind the spatially periodic and kinklike distortions that can appear in a homogeneously aligned microsized nematic volume under the influence of crossed electric and magnetic fields. Numerical studies show that when the electric field is directed close to a right angle to the magnetic field, two scenarios of director field reorientation can be realized. Additionally, under certain conditions, a distortion in the form of a kinklike wave spreading normally to the horizontal bounding surfaces with a velocity in a few meters per second can be excited in the microsized nematic volume.
Article
Chemistry, Physical
Kelum Perera, Rony Saha, Pawan Nepal, Rohan Dharmarathna, Md Sakhawat Hossain, Md Mostafa, Alex Adaka, Ronan Waroquet, Robert J. Twieg, Antal Jakli
Summary: The experimental results and theoretical considerations of novel electromechanical effects of ferroelectric nematic liquid crystal droplets coexisting with the isotropic melt are presented in this study. It is found that the droplets have flat pancake-like shapes thinner than the sample thickness. A wing-shaped defect with low birefringence is present in the center of the droplets, moving perpendicular to a weak electric field, and dividing into two at higher fields. The entire droplet drifts along the electric field with a speed independent of droplet size and proportional to the electric field amplitude.
Article
Optics
Esther Nabadda, Guadalupe Lopez-Morales, David Marco, Maria del Mar Sanchez-Lopez, Ignacio Moreno
Summary: This work presents a comprehensive polarimetric study of a twisted-nematic liquid-crystal cell, introducing a new Mueller matrix approach to simplify previous analyses and resolve ambiguities in determining physical parameters.
OPTICS AND LASER TECHNOLOGY
(2022)
Review
Multidisciplinary Sciences
Izabela Sliwa, Pavel Maslennikov, Alex Zakharov
Summary: This review focuses on the physical mechanism behind the appearances of traveling and non-traveling distortions in twisted microsized nematic volumes under the effect of a large electric field. It analyzes both experimental and theoretical works related to the excitation of structured periodic domains and electrically driven distortions in liquid crystal systems.
Article
Multidisciplinary Sciences
Tianyi Yao, Ziga Kos, Qi Xing Zhang, Yimin Luo, Edward B. Steager, Miha Ravnik, Kathleen J. Stebe
Summary: Topological defects on rotating colloids in nematic liquid crystals form far-from-equilibrium structures that perform complex swim strokes, generating translation from rotation. The swimmer's speed and direction are determined by the topological defect's polarity and extent of elongation. Control over particle trajectories can be achieved by manipulating the elongation of defects using a rotating external magnetic field. The anisotropic viscosities associated with the defect elongation, lubrication forces, and line tensions between the colloid and the bounding surfaces contribute to the swimmers' translational motion and interaction.
Article
Physics, Fluids & Plasmas
Marcell Tibor Mathe, Agnes Buka, Antal Jakli, Peter Salamon
Summary: A thermal gradient-induced circular motion of particles placed on ferroelectric nematic liquid crystal sessile drops is shown and explained in this study. The experiments demonstrate the unique properties of fluid ferroelectric liquid crystals, where the laminar flow drives the rotation of particles and gives them electric charge.
Article
Chemistry, Multidisciplinary
Ya-Zi Wang, Jieh-Wen Tsung
Summary: A large 2D topological defect array in a nematic liquid crystal exhibits a translucent watery hazy texture, which is a combination of light scattering, lens imaging, and diffraction. The traditional haze measurement is unable to distinguish between scattered and diffracted light, while the spatial spectrum accurately describes the perceived appearance. Small annulus electrodes in a hexagonal array produce the messiest defects, haziest texture, and most comfortable visual experience among the others.
Article
Multidisciplinary Sciences
Per Rudquist
Summary: The recent discovery of spontaneously polar nematic liquid crystals, known as ferroelectric nematics, has attracted significant interest. So far, experimental verification of this phase has been challenging. A direct method for experimental verification has been proposed, utilizing a single sample cell and observing the orientation of disclination lines to reveal the ferroelectric nematic phase.
SCIENTIFIC REPORTS
(2021)
