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 (VO₂) 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 VO₂. Compared to traditional VO₂ 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 VO₂ shell to couple with the core, greatly enhancing heat transfer with the insulating VO₂, while blocking the motivation of the core in the metallic state of VO₂. The proposed switch opens pathways for active control of NFRHT and holds practical significance for developing thermal photon-based logic circuits.