Induced polarization response and integrated magnetic resonance show prosperous advantages in boosting electromagnetic wave absorption but still face huge challenges in revealing the intrinsic mechanism. In this work, we propose a self-confined strategy to construct hierarchical Fe-Co@TiO2 microrods with numerous incoherent heterointerfaces and gradient magnetic domains. The results demonstrate that the use of polyvinylpyrrolidone (PVP) coating is crucial for the subsequent deposition of Co-zeolitic imidazolate frameworks (ZIF-67), the distance of ordered arranged metal ions manipulates the size of magnetic domains, and the pyrolysis of PVP layers restricts the eutectic process of Fe-Co alloys to some extent. As a result, these introduced lattice defects, oxygen vacancies, and incoherent heterointerfaces inevitably generate a strong polarization response, and the regulated gradient magnetic domains realize integrated magnetic resonance, including macroscopic magnetic coupling, long-range magnetic diffraction, and nanoscale magnetic bridge connection, and both of the intrinsic mechanisms in dissipating electromagnetic energy are quantitatively clarified by Lorentz off-axis electron holography. Owing to the cooperative merits, the Fe-Co@TiO2 absorbents exhibit enhanced absorption intensity and strong absorption bandwidth. This study inspires us to develop a generalized strategy for manipulating the size of magnetic domains, and the integrated magnetic resonance theory provides a versatile methodology in clarifying magnetic loss mechanism.
Keywords: defects/vacancies; electromagnetic wave absorption; electron holography; gradient magnetic domains; incoherent heterointerfaces.