Temperature dependence of the plasmonic Casimir interaction

TL;DR

This paper explores how surface plasmons influence the temperature-dependent Casimir effect, revealing conditions where the force switches from attractive to repulsive, especially out of thermal equilibrium.

Contribution

It provides an analytical study of the thermal Casimir interaction involving surface plasmons, including out-of-equilibrium scenarios, highlighting the potential for repulsive forces.

Findings

Thermal effects are negligible at small separations and room temperature.

The Casimir force can become repulsive at large distances or temperatures.

Selective excitation of surface plasmons can induce repulsion out of thermal equilibrium.

Abstract

We investigate the role of surface plasmons in the electromagnetic Casimir effect at finite temperature, including situations out of global thermal equilibrium. The free energy is calculated analytically and expanded for different regimes of distances and temperatures. Similar to the zero-temperature case, the interaction changes from attraction to repulsion with distance. Thermal effects are shown to be negligible for small plate separations and at room temperature, but become dominant and repulsive at large values of these parameters. In configurations out of global thermal equilibrium, we show that the selective excitation of surface plasmons can create a repulsive Casimir force between metal plates.