Axially Oriented Magnetic‐Carbon Fibers via Confined Electrospinning for Tunable Broadband Electromagnetic Wave Absorption

Abstract Wide‐frequency response in electromagnetic (EM) wave absorption materials usually depends on the composition ratio or macro‐structure design. How to achieve axial orientation arrangement of magnetic nanoparticles in 1D carbon fibers faces huge challenges. In this work, axially oriented magnetic‐carbon (Fe@NC) fibers are fabricated via confined electrospinning and pyrolysis, where spindle‐shaped Fe nanoparticles (NPs) are in situ confined within carbonized PAN fibers with their axial direction aligned along the fiber orientation, forming a synergistic heterostructure. Aligned Fe@NC fibers enhanced anisotropy and assembled 3D fiber network boosted electron transfer and magnetic coupling, co‐contributing to the energy dissipation. And the micromagnetic simulations revealed the evolution of magnetic domains with increasing magnetic Fe NPs. Benefiting from the dielectric‐magnetic synergy, the optimized Fe@NC composite achieved exceptional broadband EM wave absorption, exhibiting an ultra‐wide effective absorption bandwidth (EAB) of 7.1 GHz (covering the entire Ku‐band) at a thin thickness of 1.7 mm. This work provides a novel strategy for designing wide‐frequency absorbers and advances the controllable synthesis of 1D axially oriented magnetic‐dielectric functional composites.