Casimir--Polder force between anisotropic nanoparticles and gently curved surfaces

TL;DR

This paper investigates how the curvature of surfaces influences the orientation-dependent Casimir--Polder force between anisotropic nanoparticles and surfaces, revealing complex dependencies on curvature, temperature, and material properties.

Contribution

It introduces a derivative expansion approach to analyze curvature effects on Casimir--Polder interactions and provides explicit results for nano-spheroids of SiO₂ and gold.

Findings

Surface curvature significantly affects nanoparticle orientation.

Temperature and material properties alter the preferred orientation.

Derived short-distance interaction potential for anisotropic particles.

Abstract

The Casimir--Polder interaction between an anisotropic particle and a surface is orientation dependent. We study novel orientational effects that arise due to curvature of the surface for distances much smaller than the radii of curvature by employing a derivative expansion. For nanoparticles we derive a general short distance expansion of the interaction potential in terms of their dipolar polarizabilities. Explicit results are presented for nano-spheroids made of SiO$_2$ and gold, both at zero and at finite temperatures. The preferred orientation of the particle is strongly dependent on curvature, temperature, as well as material properties.