Nanoscale heat flux between anisotropic uniaxial media

TL;DR

This paper theoretically investigates near-field heat transfer between anisotropic uniaxial media, revealing that air inclusions can significantly enhance heat flux through additional surface waves and resonant modes.

Contribution

It introduces a combined stochastic electrodynamics and Maxwell-Garnett approach to show how air inclusions boost heat transfer between anisotropic materials.

Findings

Heat flux can be greatly increased by air inclusions.

Extraordinary surface waves create new heat transfer channels.

Resonance and frustrated modes contribute to enhanced heat transfer.

Abstract

We present a theoretical study of near-field heat transfer between two anisotropic materials separated by a small vacuum gap and maintained in a stationary non-equilibrium thermal situation. By combining standard stochastic electrodynamics and the Maxwell-Garnett description for effective media, we show that heat flux can be significantly enhanced by air inclusions. This result is explained by : (a) the presence of extraordinary surface waves that give rise to supplementary channels for heat transfer throughout the gap, (b) an increase in the contribution given by the ordinary surface waves at resonance, (c) and the appearance of frustrated modes over a broad spectral range.