Enhancement and tunability of near-field radiative heat transfer mediated by surface plasmon polaritons in thin plasmonic films

TL;DR

This paper demonstrates that ultra-thin plasmonic films significantly enhance near-field radiative heat transfer through surface plasmon polariton coupling, and this effect can be dynamically tuned using different substrates and phase change materials.

Contribution

It introduces a rigorous electrodynamics model showing dramatic heat transfer enhancement in thin plasmonic films and explores tunability via substrate and phase change materials.

Findings

Heat transfer exceeds bulk and dielectric levels by over an order of magnitude.

Spectral broadening of heat flux is due to SPP coupling on thin films.

Substrate choice enables spectral shaping and dynamic control of heat transfer.

Abstract

The properties of thermal radiation exchange between hot and cold objects can be strongly modified if they interact in the near field where electromagnetic coupling occurs across gaps narrower than the dominant wavelength of thermal radiation. Using a rigorous fluctuational electrodynamics approach, we predict that ultra-thin films of plasmonic materials can be used to dramatically enhance near-field heat transfer. The total spectrally integrated film-to-film heat transfer is over an order of magnitude larger than between the same materials in bulk form and also exceeds the levels achievable with polar dielectrics such as SiC. We attribute this enhancement to the significant spectral broadening of radiative heat transfer due to coupling between surface plasmon polaritons (SPPs) on both sides of each thin film. We show that the radiative heat flux spectrum can be further shaped by the choice of the substrate onto which the thin film is deposited. In particular, substrates supporting surface phonon polaritons (SPhP) strongly modify the heat flux spectrum owing to the interactions between SPPs on thin films and SPhPs of the substrate. The use of thin film phase change materials on polar dielectric substrates allows for dynamic switching of the heat flux spectrum between SPP-mediated and SPhP-mediated peaks.