Magnetic Metacomposites with Tunable ε'-Negative Response Achieved by Dual-Functional Phase Paradigm

Metacomposites have achieved a controllable ε'-negative (ε' < 0) response in the radio frequency band, and thus have shown attractive application prospects in fields such as antenna design, radar stealth, new filters, and sensors. Therefore, in this work, the dual-functional phase metacomposites was developed based on the composite design strategy of conductors/insulators. In it, carbon nanotube-carbon black (CNT-CB) prepared by electrostatic self-assembly process was used as the conductor phase, and magnetic ferric oxide (Fe₃O₄) prepared by in-situ reduction was used as the insulating phase. An ε'-negative response in the 20 MHz-1 GHz region was successfully achieved, and the ε' value has been precisely regulated at the order of 10³. This is because the successful construction of the three-dimensional (3D) CNT-CB network enables the metacomposites to achieve the plasmonic oscillation effect, which is regulated by the effective carrier concentration and the damping effect of the Fe₃O₄ insulator. We analyzed the structure-function relationship of the metacomposites through the electrical percolation model and equivalent circuit analysis. Finally, we investigated the response characteristics of extremely weak ε'-negative (-10 < ε' < 0) metacomposites at 1 GHz frequency to electromagnetic waves through 3D radar scattering simulation and thermal infrared imaging. Our work will provide a new design paradigm of magnetic metacomposites based on dual-functional phases and offer a new perspective for in-depth clarification of the precise regulation mechanism of ε'-negative response.