Orientation‐Programmed Effective Fields in FeCo@N‐rGO Magnetic Chains for Multifunctional Electromagnetic Materials

ABSTRACT Anisotropic microwave absorbers offer designable performance for next‐generation electronic devices, yet the underlying orientation‐performance mechanism remains unclear, and heat accumulation and short‐circuit risks persist. Here, chain‐like FeCo@N‐rGO/silicone composites with controlled 0°, 45°, and 90° orientations are fabricated by interfacial adsorption‐carbonization and magnetic‐field‐assisted hot pressing. The ultrathin N‐rGO shell amplifies interfacial and dipolar polarization, enabling effective absorption at 25 wt.% in paraffin and 35 wt.% in silicone, lower than most reported magnetic metal absorbers with comparable absorption intensity. The 45° orientation delivers an ultrawide absorption bandwidth of 7.7 GHz with a minimum reflection loss of −49.84 dB, whereas the 90° orientation covers low‐frequency 5G bands. An effective‐field mechanism is established, revealing that orientation regulates depolarization and shape‐anisotropy fields, thereby decoupling polarization, magnetic resonance, conduction, and eddy‐current losses. The oriented composites further achieve an in‐plane thermal conductivity of 4.07 W·m −1 ·K −1 and an insulating resistivity of 8.7 × 10 11 Ω·cm, establishing an orientation‐field‐loss design principle for multifunctional anisotropic electromagnetic materials.