Effects of spatial dispersion in near-field radiative heat transfer between two parallel metallic surfaces

TL;DR

This paper investigates near-field radiative heat transfer between metallic surfaces at nanometer scales, revealing saturation effects due to skin depth and analyzing local versus non-local dielectric models.

Contribution

It demonstrates that heat flux saturates at distances below the skin depth and compares local and non-local models, explaining experimental saturation as due to eddy currents.

Findings

Heat flux saturates below the skin depth.

Local and non-local models agree above 2 nm gap.

Eddy currents mainly dissipate heat in metals.

Abstract

We study the heat transfer between two parallel metallic semi-infinite media with a gap in the nanometer-scale range. We show that the near-field radiative heat flux saturates at distances smaller than the metal skin depth when using a local dielectric constant and investigate the origin of this effect. The effect of non-local corrections is analysed using the Lindhard-Mermin and Boltzmann-Mermin models. We find that local and non-local models yield the same heat fluxes for gaps larger than 2 nm. Finally, we explain the saturation observed in a recent experiment as a manifestation of the skin depth and show that heat is mainly dissipated by eddy currents in metallic bodies.