Graphene-based enhancement of near-field radiative-heat-transfer rectification

Abstract

We present a thermal device based on the near-field interaction between two substrates made of a polar and a metal-insulator-transition material. As a result of the temperature dependence of the optical properties, this device acts as a thermal rectifier, implying a strong asymmetry in the heat flux when reversing the two temperatures. By covering both substrates with a graphene sheet, we show a significant enhancement of rectification coefficient. The investigation of the flux spectral properties along with its distance dependence allows us to prove that this enhancement is associated with a change in the power-law dependence of the heat flux with respect to the separation distance in the electrostatic regime due to the presence of graphene sheets. Our results highlight the promising role of graphene-based hybrid structures in the domain of nanoscale thermal management.