Temperature-activated switchable mid-infrared nonreciprocal thermal radiation based on Weyl semimetal and phase change materials

A switchable mid-infrared nonreciprocal thermal radiation (NTR) device is proposed by integrating Weyl semimetal, germanium (Ge), Ge₂Sb₂Te₅ (GST), and VO₂ into a multilayered architecture. The device achieves a maximum nonreciprocal value of 0.94 at a wavelength of 8.92 µm. The nonreciprocal value shifts from 0.027 to 0.61 when VO₂ transitions its phase while GST remains crystalline. The NTR switch operates by thermally inducing the insulator-to-metal transition in VO₂, toggling the device between "on" and "off" states. The structure maintains high nonreciprocal performance across various incident angles, indicating practicality for real-world applications. This research introduces a novel, to the best of our knowledge, strategy for switchable mid-infrared NTR and enhances energy harvesting and conversion efficiency.