Casimir-Polder attraction and repulsion between nanoparticles and graphene in out-of-thermal-equilibrium conditions

TL;DR

This paper studies how nonequilibrium thermal conditions affect the Casimir-Polder force between nanoparticles and graphene, revealing temperature-dependent attraction and repulsion effects that could impact nanotechnology and bioelectronics.

Contribution

It introduces a theoretical framework using the Dirac model and polarization tensor to analyze nonequilibrium Casimir-Polder forces involving graphene.

Findings

Force magnitude increases with graphene temperature.

Force becomes repulsive at larger separations when graphene is cooler than the environment.

Attractive force can vanish at certain distances, leading to repulsion.

Abstract

The nonequilibrium Casimir-Polder force between a nanoparticle and a graphene sheet kept at different temperatures is investigated in the framework of Dirac model using the formalism of the polarization tensor. It is shown that the force magnitude increases with increasing temperature of a graphene sheet. At larger separations an impact of nonequilibrium conditions on the force becomes smaller. According to our results, the attractive Casimir-Polder force vanishes at some definite nanoparticle-graphene separation and becomes repulsive at larger separations if the temperature of a graphene sheet is smaller than that of the environment. This effect may find applications both in fundamental investigations of graphene and for the control of forces in microdevices of bioelectronics.