Casimir-Lifshitz interaction between ZnO and SiO2 nanorods in bromobenzene: retardation effects turn the interaction repulsive at intermediate separations

TL;DR

This paper investigates the Casimir-Lifshitz interaction between ZnO and SiO2 nanorods in bromobenzene, revealing how retardation effects can cause the force to become repulsive at intermediate distances, with implications for nanotechnology.

Contribution

It provides a detailed analysis of how retardation effects influence the Casimir-Lifshitz force between nanorods in a specific medium, highlighting the conditions for repulsion.

Findings

Retardation effects induce repulsion at intermediate separations.

Van der Waals force remains attractive at all distances.

Dielectric function crossings explain the force behavior.

Abstract

We consider the interaction between a ZnO nanorod and a SiO2 nanorod in bromobenzene. Using optical data for the interacting objects and ambient we calculate the force - from short-range attractive van der Waals force to intermediate range repulsive Casimir-Lifshitz force to long range entropically driven attraction. The nonretarded van der Waals interaction is attractive at all separations. We demonstrate a retardation driven repulsion at intermediate separations. At short separations (in the nonretarded limit) and at large separations (in the classical limit) the interaction is attractive. These effects can be understood from an analysis of multiple crossings of the dielectric functions of the three media as functions of imaginary frequencies.