Gradient flexoelectric switching response in a nematic phenyl benzoate

Pramoda Kumar, K. S. Krishnamurthy

Research output: Contribution to journalArticlepeer-review

23 Scopus citations

Abstract

We report on the inverse flexoelectric effects observed in a nematic liquid crystal with a small positive dielectric anisotropy subject to static and very low frequency (<1 Hz) a.c. fields. The Bobylev-Pikin flexobands appear at a temperature-dependent d.c. threshold. Under square wave excitation, a new type of transient optical response occurs soon after each polarity reversal, and we ascribe it to the gradient flexoelectric distortion explicable on the basis of the presence of intrinsic double layers. This instability is characterized by a threshold voltage that decreases with temperature. Its maximum amplitude increases linearly with voltage close to threshold, and occurs after polarity reversal at a time τm that scales inversely as the voltage; τm decreases exponentially with frequency and temperature. After each polarity change, the ionic current following the charging current decreases almost exponentially to a non-zero value; the residual current increases monotonically with the applied bias.

Original languageEnglish
Pages (from-to)257-266
Number of pages10
JournalLiquid Crystals
Volume34
Issue number2
DOIs
StatePublished - 1 Feb 2007
Externally publishedYes

ASJC Scopus subject areas

  • General Chemistry
  • General Materials Science
  • Condensed Matter Physics

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