Multiscale magnetic-dielectric coupling in nano-micro-macro Fe/Fe3O4@C aerogels via confinement strategy for broadband electromagnetic wave absorption

Rational design of magnetic-dielectric composites proves essential for developing broadband electromagnetic (EM) wave absorbers. However, the non-uniform distribution of magnetic particles within the carbon matrix significantly reduces magnetic coupling efficiency. To overcome this, we employ a confinement strategy to fabricate Fe/Fe 3 O 4 @C composite aerogels that feature a multiscale magnetoelectric coupling network. The confined-growth Fe/Fe 3 O 4 @C nanoscale magnetic‑carbon units construct high-density heterogeneous interfaces, enhancing charge accumulation and interfacial polarization, thereby further strengthening energy dissipation. Meanwhile, under the confinement of the aerogel framework, metal-organic frameworks (MOFs) derived materials in the 2D magnetized micro-flakes maintain their octahedral morphology and collectively establish a continuous, stable nano-micro-macro magnetic coupling network. Moreover, the theoretical investigations including density functional theory calculations, COMSOL Multiphysics simulation, and radar cross-section simulation systematically elucidate the structure-property relationships governing dielectric behavior, magnetic properties, and absorption bandwidth. Notably, the optimized Fe/Fe 3 O 4 @C exhibits remarkable EM absorption performance, achieving a reflection loss of −48.44 dB and a broad bandwidth of 6.88 GHz at 2.15 mm thickness, fully covering the Ku band. Moreover, constructing the periodic structure enables an ultrabroadband absorption of 11.36 GHz at a thickness of only 4.15 mm. This study provides an idea for fabricating multifunctional EM wave absorbers with lightweight, broadband absorption, hydrophobic, thermal insulation, and infrared stealth properties.