Mechanism of field-induced unwinding of SmC* helix and bias field dependencies of dielectric permittivity and effective polarizationJang-Kun Song, U. Manna and J. K. Vij
Department of Electronic and Electrical Engineering, Trinity College, University of Dublin - Dublin 2, Ireland, EU
received 24 January 2008; accepted in final form 29 February 2008; published April 2008
published online 28 March 2008
We propose an unwinding model based on helical fractures confirmed by spectroscopic and microscopic observations. This model combined with the fixed helical pitch can explain the various physical phenomena observed in SmC* phase of ferroelectric liquid crystals. These are the dc field dependencies of i) dielectric strength, ii) relaxation frequency of the Goldstone mode, and iii) the effective polarization. The conventional diverging pitch model where the helical pitch increases with an increase in the field is shown not to satisfactorily explain these observations.
61.30.Dk - Continuum models and theories of liquid crystal structure.
61.72.Lk - Linear defects: dislocations, disclinations.
77.84.Nh - Liquids, emulsions, and suspensions; liquid crystals.
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