Impact of Mass-Gap on the Dispersion Interaction of Nanoparticles with Graphene out of Thermal Equilibrium

TL;DR

This study investigates how the mass-gap parameter in gapped graphene influences the nonequilibrium dispersion forces on nearby nanoparticles, revealing that these forces remain attractive and depend on thermal conditions, with implications for nanodevice design.

Contribution

The paper extends Lifshitz theory to out-of-thermal-equilibrium conditions for gapped graphene, providing explicit polarization tensor expressions and analyzing the mass-gap's impact on dispersion forces.

Findings

Mass-gap affects the magnitude of the dispersion force.

Nonequilibrium forces remain attractive unlike in pristine graphene.

Results can inform nanodevice design involving graphene and nanoparticles.

Abstract

We consider the nonequilibrium dispersion force acting on nanoparticles on the source side of gapped graphene sheet. Nanoparticles are kept at the environmental temperature, whereas the graphene sheet may be either cooler or hotter than the environment. Calculation of the dispersion force as a function of separation at different values of the mass-gap parameter is performed using the generalization of the fundamental Lifshitz theory to the out-of-thermal-equilibrium conditions. The response of gapped graphene to quantum and thermal fluctuations of the electromagnetic field is described by the polarization tensor in (2+1)-dimensional space-time in the framework of the Dirac model. The explicit expressions for the components of this tensor in the area of evanescent waves are presented. The nontrivial impact of the mass-gap parameter of graphene on the nonequilibrium dispersion force, as compared to the equilibrium one, is determined. It is shown that, unlike the case of a pristine graphene, the nonequilibrium force preserves an attractive character. The possibilities of using the obtained results in the design of micro- and nanodevices incorporating nanoparticles and graphene sheets for their functionality are discussed.