Microscopic origin of spontaneous polarization in ferroelectric SC* liquid crystals
作者:
B. Kutnjak-urbanc,
B. Žekš,
期刊:
Liquid Crystals
(Taylor Available online 1995)
卷期:
Volume 18,
issue 3
页码: 483-488
ISSN:0267-8292
年代: 1995
DOI:10.1080/02678299508036648
出版商: Taylor & Francis Group
数据来源: Taylor
摘要:
The origin of spontaneous polarization in the ferroelectric smectic C* phase is investigated within a mean-field microscopic model which describes the coupling between the tilt of molecules from the normal to the smectic layers and the rotation of a molecule around its long axis. The mean-field potential is studied which takes into account a chiral polar and a non-chiral quadrupolar biasing of the rotation of molecules around the molecular long axes. Each molecule is characterized by three transverse molecular axes: the chiral axis which turns parallel to the macroscopic C2axis at small tilts, the polar axis in the direction of the transverse dipole moment and the quadrupolar axis which tends to be parallel to the C2axis at very large tilts. A numerical analysis of the model shows that there are four different types of spontaneous polarization dependent on the temperature, including the sign-reversal type. The influence of three microscopic parameters, i.e. two angles between the three characteristic axes and the relative strength of the chiral versus the non-chiral biasing, on the type of spontaneous polarization is investigated. The relationship between the microscopic and the equivalent Landau model is established and discussed.
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