Ferroelectric behavior of orthogonal smectic phase made of bent-core molecules. Journal Article uri icon

Overview

abstract

  • Ferroelectric behavior in the recently reported orthogonal ferroelectric Sm-A(d)P(F) phase in an unsymmetric bent-core molecule with a carbosilane terminal group was studied. The ferroelectricity of the Sm-A(d)P(F) phase was unambiguously confirmed by optical second-harmonic generation activity in the absence of an electric field, ferroelectric response, and high dielectric strength. The long-range polar order is a consequence of weakened interlayer coupling due to the formation of carbosilane sublayers, which allows for the parallel order of dipole moments of bent-core molecules in the neighboring layers. It develops in the system gradually through the second-order phase transition from the orthogonal Sm-A(d) phase. In the Sm-A(d)P(F) phase the strong surface anchoring results in the splay of polarization across the sample thickness. The polar surface anchoring also brings about strongly thickness-dependent polar fluctuations, as proved by the dielectric measurements (Goldstone-like mode). The relaxation frequency and dielectric strength vary more than one order of magnitude with cell thickness; in particular the dielectric strength attains more than 2000 in a 25 μm-thick cell and continues to increase for thicker cells. Simple theory developed qualitatively explains the experimental results, supporting the polarization splay model proposed.

publication date

  • September 1, 2011

Full Author List

  • Guo L; Gorecka E; Pociecha D; Vaupotič N; Čepič M; Reddy RA; Gornik K; Araoka F; Clark NA; Walba DM

Other Profiles

Additional Document Info

start page

  • 031706

volume

  • 84

issue

  • 3 Pt 1