LAUSR

FeCo alloy nanoparticles, as a kind of material with high saturation magnetization, have attracted wide attention in electromagnetic (EM) wave research. However, its application as a wave‐absorbing material is limited by its poor magnetic anisotropy and antioxidant properties. Herein, novel FeCo/Polyvinylpyrrolidone core‐shell nanochains@graphene oxide (GO) composites are successfully fabricated with superior microwave‐absorbing properties. The composites perform excellently in absorbing EM wave, with a strong reflection loss (RL) of −40.94 dB at 14.25 GHz, covering from 10.95 to 15.85 GHz (RL < −10 dB) with a matching thickness of 2.0 mm. The superior absorption properties are mainly attributed to the cooperation between amorphous magnetic FeCo nanoparticles and graphene, which contribute to the magnetic and dielectric loss, respectively. Moreover, the FeCo/PVP core‐shell morphology enhances the interfacial relaxation and surface chemical stability of the FeCo nanochains. Thus, this work provides a template for the new‐designed and facile‐synthesized EM wave‐absorbing material.