# Near-field thermal radiative transfer between two coated spheres

## TL;DR

This paper derives an expression for near-field thermal radiative transfer between coated spheres, revealing novel spectral features and conditions where layered spheres outperform homogeneous ones in heat transfer.

## Contribution

It introduces a new analytical model for heat transfer between coated spheres and uncovers unique spectral phenomena and enhanced conductance due to layering effects.

## Key findings

- Spectral peaks at non-resonant frequencies due to coatings
- Near-field selective emission observed in metallic spheres with polar coatings
- Layered spheres can surpass homogeneous spheres in total conductance

## Abstract

In this work, we present an expression for the near-field thermal radiative transfer between two spheres with an arbitrary numbers of coatings. We numerically demonstrate that the spectrum of heat transfer between layered spheres exhibits novel features due to the newly introduced interfaces between coatings and cores. These features include broad super-Planckian peaks at non-resonant frequencies and near-field selective emission between metallic spheres with polar material coatings. Spheres with cores and coatings of two different polar materials are also shown to exceed the total conductance of homogeneous spheres in some cases.