Epsilon‐Negative Derived Electromagnetic Wave Absorption of Magnetic Metacomposites by Bifunctional Phase Paradigm

Abstract Electromagnetic (EM) metacomposites possess exceptional capabilities for manipulating EM waves within the microwave frequency spectrum. However, their current designs lack a systematic structural framework, leading to ambiguity in the regulation of their EM parameters. This study presents a multifunctional phase paradigm for metacomposites that combines the conductive phase of graphene (GR) with the insulating phase of Fe ₃ O ₄ . In this arrangement, Bi nanoparticles act as electronic transport bridges, effectively linking GR and Fe ₃ O ₄ particles. This structure‐function relationship facilitates the achievement of a ε' ‐negative response in the frequency range of 10 ⁴ –10 ⁵ across the 10 MHz –1 GHz band, demonstrating stable regulation. The Drude model is employed to elucidate the frequency dependence of negative permittivity, highlighting the plasmonic oscillation effect within GR networks. Meanwhile, analysis of EM simulation results indicates that the ε' ‐negative medium induces significant EM wave loss due to enhanced polarization effects stemming from the carbon network and the multi‐interface structure of the GR/Bi@Fe ₃ O ₄ metacomposites. The optimized ε' ‐negative metacomposites achieve a reflection loss of −50.69 dB at 13.6 GHz, driven by the synergistic effects of GR's conductive loss, Fe ₃ O ₄ ’s magnetic loss, and multi‐scale interface polarization effects.