Light scattering by a metallic nanoparticle coated with a nematic liquid crystal

TL;DR

This paper investigates how a nematic liquid crystal coating affects the optical scattering properties of a gold nanoparticle, revealing that strong anchoring and inhomogeneities can enhance light extinction across visible wavelengths.

Contribution

It introduces a combined theoretical and computational approach to analyze the impact of nematic liquid crystal coatings on nanoparticle optical responses, highlighting the role of anchoring conditions and inhomogeneities.

Findings

Anisotropy of the coating has minimal effect on optical response.

Strong anchoring leads to inhomogeneous coatings with ring singularities.

Inhomogeneities enhance the extinction spectrum across visible light.

Abstract

We study the optical properties of gold nanoparticles coated with a nematic liquid crystal whose director field is distributed around the nanoparticle according to the anchoring conditions at the surface of the nanoparticle. The distribution of the nematic liquid crystal is obtained by minimization of the corresponding Frank free-energy functional whilst the optical response is calculated by the discrete-dipole approximation. We find, in particular, that the anisotropy of the nematic liquid-crystal coating does not affect much the (isotropic) optical response of the nanoparticle. However, for strong anchoring of the nematic liquid-crystal molecules on the surface of nanoparticle, the inhomogeneity of the coating which is manifested by a ring-type singularity (disclination or Saturn ring), produces an enhancement of the extinction cross spectrum over the entire visible spectrum.