High anisotropy 2D large-size iron-based coral for C-band ultra-wide microwave absorption

Lightweight microwave-absorbing (MA) materials with broadband absorption in the C-band remain challenging to date. Recent studies have shown that promoting anisotropy in materials is expected to break the Snoek limit and enhance the absorption performance of magnetic materials in the C-band. In this paper, two-dimensional (2D) large-size coral-like iron-based composites (LCIC) were prepared using an NH₄NO₃-assisted blow molding separation strategy. The special structure with large shape anisotropy realizes a wide and strong natural magnetic resonance, leading to strong magnetic loss. The enhanced natural resonance effectively broadens the effective absorption bandwidth (EAB) of the LCIC in the C-band. The minimum reflection loss (RL_min) of LCIC is −41.64 dB, and the EAB is 5.42 GHz (3.83–9.25 GHz), covering the entire C-band. Strong natural resonance is necessary to improve the dissipation of magnetic losses in low-frequency electromagnetic waves. This work explores the important role of size effect in enhancing the C-band absorption properties of magnetic materials. It provides a feasible reference for the preparation of C-band broadband, strongly absorbing MA materials.