Photonic thermal switch via metamaterials made of vanadium dioxide-coated nanoparticles.

In this work, a photonic thermal switch is proposed based on the phase-change material vanadium dioxide (VO) within the framework of near-field radiative heat transfer (NFRHT). The switch consists of two metamaterials filled with core-shell nanoparticles, with the shell made of VO. Compared to traditional VO slabs, the proposed switch exhibits a more than two times increase in the switching ratio, reaching as high as 90.29% with a 100 nm vacuum gap. The improved switching effect is attributed to the capability of the VO shell to couple with the core, greatly enhancing heat transfer with the insulating VO, while blocking the motivation of the core in the metallic state of VO. The proposed switch opens pathways for active control of NFRHT and holds practical significance for developing thermal photon-based logic circuits.