TY - JOUR

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

PY - 2016/2/12

Y1 - 2016/2/12

N2 - 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.

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.

KW - helicoidal structure

KW - chiral modulated nematics

KW - archiral modulated nematics

U2 - 10.1103/PhysRevE.93.022704

DO - 10.1103/PhysRevE.93.022704

M3 - Article

VL - 93

JO - Physical Review E: Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics

JF - Physical Review E: Statistical Physics, Plasmas, Fluids, and Related Interdisciplinary Topics

SN - 1539-3755

IS - 2

M1 - 022704

ER -