Near-field thermal transport between twisted bilayer graphene

TL;DR

This study investigates how twisting bilayer graphene affects near-field thermal radiation, revealing tunable heat flow and special angles that optimize thermal transfer, with implications for thermal management and energy applications.

Contribution

It provides a fluctuational electrodynamic analysis of TBLG, uncovering the dependence of heat flow on twist angle and chemical potential, and identifying conditions for maximal thermal transfer.

Findings

Heat flow varies over 10-fold with twist angle.

Special angles lead to heat flow extrema.

Multiband thermal transport observed at small twist angles.

Abstract

Active control of heat flow is of both fundamental and applied interest in thermal management and energy conversion. Here, we present a fluctuational electrodynamic study of thermal radiation between twisted bilayer graphene (TBLG), motivated by its unusual and highly tunable plasmonic properties. We show that near-field heat flow can vary by more than 10-fold over only a few degrees of twist, and identify special angles leading to heat flow extrema. These special angles are dictated by the Drude weight in the intraband optical conductivity of TBLG, and are roughly linear with the chemical potential. Further, we observe multiband thermal transport due to the increasing role of interband transitions as the twist angle decreases, in analogy to monolayer graphene in a magnetic field. Our findings are understood via the surface plasmons in TBLG, and highlight its potential for manipulating radiative heat flow.