Thick smectic shells

TL;DR

This paper investigates how increasing thickness in smectic shells on spheres causes layer distortions and leads to chevron-like structures, revealing the interplay of elasticity, curvature, and anchoring in these systems.

Contribution

It introduces a perturbative approach to analyze thick smectic shells, showing the breakdown of the thin-film ground state and the emergence of periodic textures.

Findings

Layer distortion occurs when film thickness increases.

Chevron-like structures form beyond a certain elastic threshold.

The wavelength of textures depends on thickness and curvature.

Abstract

The known ground state of ultrathin smectic films confined to the surface of a sphere is described by four +1/2 defects assembled on a great circle and a director which follows geodesic lines. Using a simple perturbative approach we show that for thick smectic films on a sphere with planar anchoring this solution breaks down, distorting the smectic layers. The instability happens when the bend elastic constant exceeds the anchoring strength times the radius of the inner sphere. Above this threshold, the formation of a periodic chevron-like structure, observed experimentally as well, relieves geometric frustration. We quantify the effect of thickness and curvature of smectic shells and provide insight into the wavelength of the observed texture.