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Title: Electroclinic effect and layer rotations in the chiral smectic C phase
Author: Jang, Joo-Nyung
Awarding Body: University of Cambridge
Current Institution: University of Cambridge
Date of Award: 2007
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In this work, we propose a model for the layer rotation of the SmC* phase, which is able to give answers to most of the basic questions about smectic layer rotation. First, it is postulated that the layer rotation is related to the electroclinic effect. We investigate the electroclinic effect in the SmC* phase, for the first time as far as we know, with three different experiments: Dielectric permittivity measurements, light transmission measurements, and direct tilt angle measurements. Next, microscopic and/or statistical molecular switching behaviour is investigated by a modified theory and verified by some measurements. From these results, we propose a mechanism from a system energy point of view. The molecules tend to maintain the lowest energy state, in which the relative position of the neighbouring molecule is determined by the tilt angle in the case of the SmC* phase. If the molecules keep their positions even after the tilt cones are rotated, there is an induced system energy increase due to the layer thickness change and the molecular coupling configuration change. We will explain with our modelling why only asymmetric waveforms can rotate the layer of the SmC* phase. The basic idea is that an induced asymmetric probability density of the director for each cycle of an asymmetric electric waveform is the origin of the layer rotation. We found that the expected results from this modelling did not conflict with the previous work.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available