On the change in helix handedness at transitions between the SmC* and phases in chiral smectic liquid crystals

Jan P.F. Lagerwall, Frank Giesseimann, Mikhail Osipov

Research output: Contribution to journalArticle

16 Citations (Scopus)

Abstract

Using a discrete model for the synclinic SmC* and the anticlinic phases we give a theoretical explanation for the fact that the helix twisting sense reverses at a transition between these phases (direct transition or via the so-called chiral smectic C 'subphases') and we derive an explicit expression for the helical pitch in the phase. As the theory shows and as we also demonstrate experimentally, the reversal is of a different nature from helix inversions within a single phase, where the inversion is always coupled to a pitch divergence. At a clinicity change the common behaviour is instead pitch-shortening on approaching the phase transition and the associated helix twisting sense reversal. The phenomenon may be put to use in smart mixing in order to control the helix pitch, either for achieving long pitch for surface-stabilized ferroelectric and antiferroelectric liquid crystal displays; or a very short pitch, in the case of devices utilizing the deformed helix mode.
Original languageEnglish
Pages (from-to)625-633
Number of pages9
JournalLiquid Crystals
Volume33
Issue number6
DOIs
Publication statusPublished - Jun 2006

Keywords

  • helix twisting
  • helix handedness
  • helical pitch
  • liquid crystal

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