Macroscopic dynamics of chiral smectic C

Abstract

2014 Nous présentons les équations hydrodynamiques qui gouvernent les propriétés macroscopiques des smectiques C chiraux. La dérivation de ces équations tient compte de la nature des symétries brisées dont les conséquences hydrodynamiques sont mises en évidence. Nous examinons en détail les similitudes et les différences entre le cas présent et celui des smectiques C non chiraux et des cristaux liquides cholestériques. Nous discutons l'influence et les conséquences de la ferroélectricité sur l'hydrodynamique et, en particulier, sur la structure des excitations hydrodynamiques. Abstract. 2014 The hydrodynamic equations describing the macroscopic behaviour of chiral smectic C are presented. To derive these equations the nature of the spontaneously broken continuous symmetries is considered and their consequences for the hydrodynamics are pointed out. Similarities and differences to achiral smectic C and cholesteric liquid crystals are investigated in some detail. The influence and the consequences of ferroelectricity on the hydrodynamics, in particular on the structure of the normal modes, is discussed. In two appendices we study flexoelectric and electrohydrodynamic effects for various other liquid crystalline phases.

Electromechanical effects in cholesteric and chiral smectic liquid‐crystalline elastomers

“…(1) is the dielectric term, the second one is the piezoelectric term, which has been discussed for cholesterics first in ref. 14) and the terms proportional to have been given previously for cholesterics in ref. "); the latter group contains for example pyroelectricity.…”

Note on « new electromechanical effect in chiral smectic C* liquid crystals »

“…In a recent Letter [1] the observation of a velocity change in the plane of the layers of a smectic C* sample due to an alternating electric field (also applied in the layer plane) was reported. It was pointed out in reference [1] that the effect observed is not contained in the continuum description of the C* phase given by the present authors [2] and it was suggested that the effect is a dissipative one.…”

Incompressibility conditions in liquid crystals

“…[12] for a detailed exposition) is applicable to systems with spontaneously broken continuous symmetries of any kind (e.g. biaxial nematics [13,14]) including strong external fields [15] and can be generalized to systems with slow nonhydrodynamic variables (like nematic polymers [16]). These theories describe generally the compressible case and the incompressibility approximation can be implemented explicitly, in order to compare with the Leslie-Ericksen approach.…”