Macroscale anomalous heat conduction in active thermal metamaterials

Anomalous heat conduction is a non-Fourier phenomenon that typically occurs at the microscale, where the mean free path of thermal carriers approaches the system size, but its macroscale counterpart has been lacking. Here, we introduce the concept of active thermal metamaterials (ATMs) based on internal source modulation, demonstrating a macroscopic analog to microscale anomalous heat conduction with size-dependent effective thermal conductivity, κ eff ∝ L β . The tunable exponent β from 0 to 1 allows for mimicking various microscale anomalous heat conduction phenomena. This approach can potentially ease the design of desired- κ materials by adjusting system size, significantly expanding the capability realm of thermal metamaterials and opening new avenues for advanced thermal management and functionalities.