Phonon-Polariton-Mediated Configurable Radiative Thermal Router

Photon-based radiative thermal router, controlling the nanoscale flow of heat, exhibits exciting potential in energy harvesting and thermal management. However, existing studies show that the terminals of thermal routers strongly depend on external field manipulations or anisotropic materials. To overcome these limitations, we propose a thermal router consisting of three isotropic particles which are placed in the proximity of a twisted bilayer made of in-plane hyperbolic materials. By twisting the bilayer to a critical status where a topological transition occurs, the heat flow can be precisely directed from the source to the drain of choice. At the photonic magic twist angle, the dispersion contours become fat; hence, the collimated group velocity and the canalization effect allow the directional propagation of energy. Furthermore, we demonstrate that the thermal router has good robustness against the variation in distance between the source and the drain particles and is sensitive to the vertex angle of the isosceles triangle. The thermal router mediated by the twisted bilayer structures can be expanded to many-particle systems due to unidirectional energy transmission. Our findings enrich the controllability of noncontact heat exchange at the nanoscale, providing an alternative way for realizing directional heat flow in nanoscale thermal routers and other related heat transfer devices.