Magnetic exchange coupling via constructing hard/soft magnetic interface for stable microwave absorption

Magnetic exchange coupling interaction at hard/soft magnetic interface can expand the frequency range of magnetic resonance, providing the stable microwave absorption performance that is insensitive to matching thickness. A novel nanocomposite, in which shell/core structured Sm2Co17/Co(Sm) hard/soft magnetic nanoparticles are embedded into Sm2O3-doped porous carbon, is prepared. The magnetic exchange coupling between hard magnetic Sm2Co17 shell and soft magnetic Co(Sm) core results in extending resonance frequency. Due to the synergistic effect of quarter-wavelength cancellation and electromagnetic loss, the nanocomposites deliver the optimal reflection loss (RLm) of −38.87 dB and effective absorption bandwidth (EAB) of 3.36 GHz at thickness of 2.5 mm and 2.7 mm, respectively, and stable microwave absorption performances (RLm ≤ -20 dB and EAB ≥ 3.0 GHz) in thickness of 2.4–3.0 mm.