Theory of monolayers with boundaries: Exact results and Perturbative analysis

TL;DR

This paper provides exact and perturbative analytic results for textures and boundary shapes in Langmuir monolayer domains and bubbles, revealing how energetic terms and thermal fluctuations influence their structure.

Contribution

It introduces a perturbative method to analyze textures and shapes of monolayer domains, offering insights into boundary features and fluctuation effects.

Findings

Analytic expressions for textures within domains and bubbles.

Perturbative analysis of boundary shapes from circular to distorted forms.

Thermal fluctuations induce a size-dependent effective line tension.

Abstract

Domains and bubbles in tilted phases of Langmuir monolayers contain a class of textures knows as boojums. The boundaries of such domains and bubbles may display either cusp-like features or indentations. We derive analytic expressions for the textures within domains and surrounding bubbles, and for the shapes of the boundaries of these regions. The derivation is perturbative in the deviation of the bounding curve from a circle. This method is not expected to be accurate when the boundary suffers large distortions, but it does provide important clues with regard to the influence of various energetic terms on the order-parameter texture and the shape of the domain or bubble bounding curve. We also look into the effects of thermal fluctuations, which include a sample-size-dependent effective line tension.