Continuum theory of tilted chiral smectic phases

TL;DR

This paper presents a continuum theoretical framework explaining the sequence of distorted commensurate phases in tilted chiral smectics through electrostatic energy considerations and the interplay of twist sources.

Contribution

It introduces a novel continuum theory that accounts for phase sequences and helicity sign changes in tilted chiral smectic phases.

Findings

Sequence of phases explained by electrostatic energy gain

Sign change of helicity due to twist source balance

Close match with experimental observations

Abstract

We demonstrate that the sequence of distorted commensurate phases observed in tilted chiral smectics is explained by the gain in electrostatic energy due to the lock-in of the unit cell to a number of layers which is the integer closest to the ratio pitch over thickness of the subjacent Sm-C$^*_\alpha$ phase. We also explain the sign change of the helicity in the middle of the sequence by a balance between two twist sources one intrinsic and another due to the distortion of the Sm-C$^*_\alpha$.