Anisotropy engineering of Prussian blue analogue derived FeNi nanoflakes for broadband electromagnetic wave absorption

Magnetic alloys are indispensable for electromagnetic (EM) wave absorption with simultaneous dielectric and magnetic loss, while balancing their permittivity and permeability is challenging. Here in-plane anisotropy has been introduced via Prussian-blue analogue (PBA) derived FeNi nanoflakes and further modulated through magnetic-field orientation. The tuned anisotropy verified by COMSOL simulations gives rise to both descendant permittivity and ascendant permeability for improved impedance matching. Meanwhile, large aspect ratio and uniform distribution of the FeNi nanoflakes result in enhanced exchange resonance for raised dissipation ability of the EM energy. As such the oriented FeNi nanoflakes exhibit impressive absorption of-44.3 dB and broad bandwidth of 7.20 GHz at a small thickness of 2.00 mm as a single-component absorber. Not only this work provides a versatile PBA-template strategy to synthesize flaky magnetic alloys with small thickness and uniform shape, enhancement mechanisms via anisotropy engineering revealed by combined experimental and simulative approaches also shed light on the future design of EM functional materials.