Theories, designs, and applications of thermal metamaterials*

With the growing concerns about energy issues, many researchers have paid their attention to thermal management. This trend was mainly driven by the emerging field of thermal metamaterials in the last decade.This report mainly introduces the new progress of thermal metamaterials in three aspects: new functions, multi-particle systems, and intelligentization. The new functions include the thermal "golden touch" and the thermal Janus structures. The former is a method to extend the core property to the shell with an extremely small core fraction. The latter is essentially a core-shell structure whose core has two distinct thermal conductivities, and the mechanical rotation of the core can realize different functions. Multi-particle systems extend the core-shell design, and the multi-particle interaction helps us achieve thermal invisibility. Intelligentization means that the effective thermal conductivity of a shell is always the same as that of the environment.