Reversed Magnetic Field‐Induced Three‐Dimensional Cage‐Type Architectures: A Scalable Route to Micron‐Scale Electromagnetic Wave Absorbers

ABSTRACT High‐performance electromagnetic wave absorbers rely on synergistic component interactions and rational structural design, particularly through engineered magnetic‐dielectric heterostructures. However, such strategies remain largely nanoscale, while micrometer‐scale systems face challenges in structural control due to limited surface reactivity. This work develops a universal flipping magnetic field‐induced assembly strategy for 3D micrometer‐sized cage architectures. Simultaneous TiN–Ni multiscale heterointerface engineering and microstructure optimization enhance magnetic‐dielectric coupling, enabling multimodal electromagnetic dissipation. Magnetic field regulation reveals a linear composition‐structure‐property relationship defining a new design paradigm. Compared with zero‐field conditions, the TiN–Ni cage structure exhibits clear enhancement in microwave absorption under a 90° flipping magnetic field of 58.17 mT. Specifically, the minimum reflection loss increases by 240% (reaching −45.74 dB), and the effective absorption bandwidth (RL < −10 dB) widens by 187% (achieving 3.14 GHz). The optimal absorption frequency shifts from the Ku–band (17.2 GHz) to the X–band (10.9 GHz), while the matching thickness is reduced from 5 mm to dual‐optimal values of 1.91 and 1.3 mm. This establishes a novel and scalable strategy for the design and fabrication of micrometer‐scale absorbers (2–100 µm).