scholarly journals Soft modes of the dielectric response in the twist–bend nematic phase and identification of the transition to a nematic splay bend phase in the CBC7CB dimer

2019 ◽  
Vol 21 (41) ◽  
pp. 22839-22848 ◽  
Author(s):  
K. Merkel ◽  
A. Kocot ◽  
C. Welch ◽  
G. H. Mehl
Keyword(s):  
Long Range ◽  
Dielectric Response ◽  
Nematic Phase ◽  
Soft Modes ◽  
Conical Angle ◽  
Collective Processes ◽  
Tilt Mode

Two collective processes resulting from distortion of the heliconical structure of the twist–bend nematic phase of an achiral dimer: one tilt mode due to distortions of the conical angle and second related to long range fluctuation of the cone phase.

scholarly journals Dielectric response of electric-field distortions of the twist-bend nematic phase for LC dimers

2019 ◽  
Vol 151 (11) ◽  
pp. 114908 ◽  
Author(s):  
K. Merkel ◽  
C. Welch ◽  
Z. Ahmed ◽  
W. Piecek ◽  
G. H. Mehl
Keyword(s):  
Electric Field ◽  
Dielectric Response ◽  
Nematic Phase

Dielectric Response of Soft Modes in Ferroelectric Thin Films

2003 ◽  
Vol 288 (1) ◽  
pp. 169-185 ◽  
Author(s):  
J. Petzelt ◽  
P. Kužel ◽  
I. Rychetský ◽  
A. Pashkin ◽  
T. Ostapchuk
Keyword(s):  
Thin Films ◽  
Dielectric Response ◽  
Ferroelectric Thin Films ◽  
Soft Modes

scholarly journals Nematic van der Waals Free-energy

2009 ◽  
Vol 1 (3) ◽  
pp. 409-421
Author(s):  
A. Oukouiss ◽  
A. Daanoun
Keyword(s):  
Free Energy ◽  
Phase Diagrams ◽  
Long Range ◽  
Nematic Phase ◽  
Van Der Waals ◽  
Spherical Particles ◽  
Liquid Equilibrium ◽  
First Order ◽  
Anisotropic Interaction ◽  
Van Der Waals Theory

We develop the calculation of free energy in a nematic phase for a model of spherical particles with the long-range anisotropic interaction from the van der Waals theory. We map the gas-liquid equilibrium, which is coupled to a first-order isotropic-nematic transition. We discus how the topology of the phase diagrams changes upon varying the strengths of the isotropic and nematic interactions.Keywords: Phase diagrams; Nematic interactions; Free energy; Transitions.© 2009 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved.DOI: 10.3329/jsr.v1i3.2595        J. Sci. Res. 1(3), 409-421 (2009)

scholarly journals History-Dependent Patterns in Randomly Perturbed Nematic Liquid Crystals

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
A. Ranjkesh ◽  
M. Ambrožič ◽  
G. Cordoyiannis ◽  
Z. Kutnjak ◽  
S. Kralj
Keyword(s):  
Phase Transition ◽  
Long Range ◽  
Nematic Phase ◽  
Lattice Simulation ◽  
Continuous Symmetry ◽  
Cylindrically Symmetric ◽  
First Order Phase Transition ◽  
Type Interaction ◽  
First Order Phase ◽  
The Impact

We study the characteristics of nematic structures in a randomly perturbed nematic liquid crystal (LC) phase. We focus on the impact of the samples history on the universal behavior. The obtained results are of interest for every randomly perturbed system exhibiting a continuous symmetry-breaking phase transition. A semimicroscopic lattice simulation is used where the LC molecules are treated as cylindrically symmetric, rod-like objects interacting via a Lebwohl-Lasher (LL) interaction. Pure LC systems exhibit a first order phase transition into the orientationally ordered nematic phase atT=Tcon lowering the temperatureT. The orientational ordering of LC molecules is perturbed by the quenched, randomly distributed rod-likeimpuritiesof concentrationp. Their orientation is randomly distributed, and they are coupled with the LC molecules via an LL-type interaction. Only concentrations below the percolation threshold are considered. The key macroscopic characteristics of perturbed LC structures in the symmetry-broken nematic phase are analyzed for two qualitatively different histories atT≪Tc. We demonstrate that, for a weak enough interaction among the LC molecules andimpurities, qualitatively different history-dependent states could be obtained. These states could exhibit either short-range, quasi-long-range, or even long-range order.

scholarly journals Macroscopic chirality of twist-bend nematic phase in bent dimers confirmed by circular dichroism

2020 ◽  
Vol 8 (3) ◽  
pp. 1041-1047 ◽  
Author(s):  
Warren D. Stevenson ◽  
Xiangbing Zeng ◽  
Chris Welch ◽  
Anil K. Thakur ◽  
Goran Ungar ◽  
...  
Keyword(s):  
Circular Dichroism ◽  
Long Range ◽  
Nematic Phase ◽  
Polarized Light ◽  
Circular Dichroism Spectroscopy ◽  
Circularly Polarized Light ◽  
Circularly Polarized ◽  
Left And Right ◽  
Circular Dichroïsm

Long-range global chirality is confirmed in the twist-bend nematic phase of bent dimers using circular dichroism spectroscopy. The phase absorbs left and right circularly polarized light differently, confirming its helical rather than wavy character.

Twist-bend nematic phase of the liquid crystal dimer CB7CB: orientational order and conical angle determined by129Xe and2H NMR spectroscopy

2015 ◽  
pp. 1-14 ◽  
Author(s):  
Jukka P. Jokisaari ◽  
Geoffrey R. Luckhurst ◽  
Bakir A. Timimi ◽  
Jianfeng Zhu ◽  
Herbert Zimmermann
Keyword(s):  
Liquid Crystal ◽  
Nmr Spectroscopy ◽  
Nematic Phase ◽  
Orientational Order ◽  
Conical Angle

Coexistence of the Phonon and Relaxation Soft Modes in the Terahertz Dielectric Response of TetragonalBaTiO3

2008 ◽  
Vol 101 (16) ◽  
Author(s):  
J. Hlinka ◽  
T. Ostapchuk ◽  
D. Nuzhnyy ◽  
J. Petzelt ◽  
P. Kuzel ◽  
...  
Keyword(s):  
Dielectric Response ◽  
Soft Modes
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