Short-range smectic fluctuations and the flexoelectric model of modulated nematic liquid crystals

Nataša Vaupotič, Samo Curk, Mikhail A. Osipov, Mojca Čepič, Hideo Takezoe, Ewa Gorecka

Research output: Contribution to journalArticle

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Abstract

We show that the flexoelectric model of chiral and achiral modulated nematics predicts the compression modulus that is by orders of magnitude lower than the measured values. The discrepancy is much larger in the chiral modulated nematic phase, in which the measured value of the compression modulus is of the same order of magnitude as in achiral modulated nematics, even though the heliconical pitch is by an order of magnitude larger. The relaxation of a one-constant approximation in the biaxial elastic model used for chiral modulated nematics does not solve the problem. Therefore, we propose a structural model of the modulated nematic phase, which is consistent with the current experimental evidence and can also explain large compression modulus: the structure consists of short-range smectic clusters with a fourfold symmetry and periodicity of two molecular distances. In chiral systems, chiral interactions lead to a helicoidal structure of such clusters.
Original languageEnglish
Article number022704
Number of pages5
JournalPhysical Review E
Volume93
Issue number2
DOIs
Publication statusPublished - 12 Feb 2016

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Nematic Liquid Crystal
liquid crystals
Fluctuations
Modulus
Range of data
Compression
periodic variations
Model
Biaxial
Structural Model
Periodicity
symmetry
Discrepancy
approximation
Symmetry
Predict
interactions
Approximation
Interaction

Keywords

  • helicoidal structure
  • chiral modulated nematics
  • archiral modulated nematics

Cite this

Vaupotič, Nataša ; Curk, Samo ; Osipov, Mikhail A. ; Čepič, Mojca ; Takezoe, Hideo ; Gorecka, Ewa. / Short-range smectic fluctuations and the flexoelectric model of modulated nematic liquid crystals. In: Physical Review E. 2016 ; Vol. 93, No. 2.
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abstract = "We show that the flexoelectric model of chiral and achiral modulated nematics predicts the compression modulus that is by orders of magnitude lower than the measured values. The discrepancy is much larger in the chiral modulated nematic phase, in which the measured value of the compression modulus is of the same order of magnitude as in achiral modulated nematics, even though the heliconical pitch is by an order of magnitude larger. The relaxation of a one-constant approximation in the biaxial elastic model used for chiral modulated nematics does not solve the problem. Therefore, we propose a structural model of the modulated nematic phase, which is consistent with the current experimental evidence and can also explain large compression modulus: the structure consists of short-range smectic clusters with a fourfold symmetry and periodicity of two molecular distances. In chiral systems, chiral interactions lead to a helicoidal structure of such clusters.",
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Short-range smectic fluctuations and the flexoelectric model of modulated nematic liquid crystals. / Vaupotič, Nataša; Curk, Samo; Osipov, Mikhail A.; Čepič, Mojca; Takezoe, Hideo; Gorecka, Ewa.

In: Physical Review E, Vol. 93, No. 2, 022704, 12.02.2016.

Research output: Contribution to journalArticle

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T1 - Short-range smectic fluctuations and the flexoelectric model of modulated nematic liquid crystals

AU - Vaupotič, Nataša

AU - Curk, Samo

AU - Osipov, Mikhail A.

AU - Čepič, Mojca

AU - Takezoe, Hideo

AU - Gorecka, Ewa

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AB - We show that the flexoelectric model of chiral and achiral modulated nematics predicts the compression modulus that is by orders of magnitude lower than the measured values. The discrepancy is much larger in the chiral modulated nematic phase, in which the measured value of the compression modulus is of the same order of magnitude as in achiral modulated nematics, even though the heliconical pitch is by an order of magnitude larger. The relaxation of a one-constant approximation in the biaxial elastic model used for chiral modulated nematics does not solve the problem. Therefore, we propose a structural model of the modulated nematic phase, which is consistent with the current experimental evidence and can also explain large compression modulus: the structure consists of short-range smectic clusters with a fourfold symmetry and periodicity of two molecular distances. In chiral systems, chiral interactions lead to a helicoidal structure of such clusters.

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KW - archiral modulated nematics

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