Customized dielectric-magnetic balance enables broadband microwave absorption in multifunctional composites via programmable relaxation polarization synergized with magnetic coupling

The traditional semi-empirical modulation strategy for composite absorbers no longer meets the design requirements for high-performance electromagnetic wave (EMW) absorbing materials. Herein, this study innovatively demonstrates the importance of a dielectric-magnetic balance in composite absorbers for broadband EMW absorption, utilizing electromagnetic (EM) calculation to determine the necessary range of EM parameters. The research highlights the dominant influence of interfacial polarization on the frequency dispersion (FD) of the real part of the permittivity. Additionally, it examines the wave-climbing effect of optimized impedance, which is induced by single-crystal porous magnetic materials. Building on these insights, we developed a dielectric-magnetic Schottky heterointerface using single-crystal (SC) porous Co₃O₄ nanosheets (Co₃O₄NSs) modified carbon fibers. Simultaneously, to achieve the matching requirement of dielectric-magnetic balance, a cation-exchange strategy is employed, whereby some Co atoms in Co₃O₄NSs are substituted with Ni and Fe atoms. This strategy optimizes both the polarization loss and the magnetic coupling effect, thereby facilitating the dielectric-magnetic synergistic absorption. Notably, the effective absorption bandwidth (EAB) of CC@Co_2.4Ni_0.3Fe_0.3O₄NSs composite reaches 9.4 GHz with only 10.0 wt% filler, indicating excellent broadband absorption performance. Furthermore, the absorber’s highly efficient multifunctional properties provide a significant advantage for practical applications.