Achieving spectral compatibility between microwave absorption (MA) and low infrared emissivity presents a formidable challenge due to the conflicting electromagnetic requirements of different bands. Herein, we engineered a gradient metamaterial utilizing heterostructured Fe@C/polythiophene composites, fabricated via integrated three-dimensional (3D) printing for achieving compatible ultra-broadband MA and low infrared emissivity. Corroborated by both experimental measurements and numerical simulations, the resulting metamaterial exhibits exceptional MA performance, achieving an ultra-broadband effective absorption bandwidth of 12.5 GHz that fully encompasses the C, X, and Ku bands. Crucially, the introduction of polythiophene further regulates the surface conductance, yielding low infrared emissivities of 0.67 (3–5 μm) and 0.48 (8–12 μm) in key atmospheric windows. The dual-functionality is attributed to the synergistic optimization of composition and structure, where the gradient architecture and heterogeneous interfaces maximize MA attenuation via impedance matching and polarization relaxation, while the regulated surface conductivity via polythiophene effectively inhibits infrared radiation. This study establishes a versatile micro-nano structural paradigm for developing high-performance metamaterials capable of countering multispectral detection.

The rapid evolution of multispectral detection systems requests stealth materials capable of simultaneously delivering strong microwave absorption and suppressed near-infrared laser reflection. This study proposes a novel rare earth (RE) doping strategy to construct a heterostructures ternary Fe₃O₄@C/REOCl (RE = Sm, Er, Dy, and Ho) through in-situ assembly-thermal reduction process. The optimized Fe₃O₄@C/REOCl demonstrates exceptional multi-spectral modulation capabilities due to the synergistic effects of multi-component dielectric loss, magnetic loss, and RE spectral modulation. The Sm³⁺-modified system (FCS) achieved effective absorption bandwidth of 5.41 GHz at 1.5 mm, and the Ho³⁺-modified system (FCH) exhibited ultralow laser reflectivity of 1.86% and 1.98% at the wavelength of 1.06 and 1.55 μm. This study introduces a unified framework that facilitates broadband microwave absorption (> 5 GHz) and dual-band laser suppression (< 2%). It establishes a universal model that can be adapted to various RE components and scalable fabrication pathways for multi-spectral stealth materials.

The growing complexity of electromagnetic (EM) interference has driven significant demand for next-generation absorbers that combine lightweight, flexibility, and good electromagnetic attenuation capability. The low-dimensional ternary Co₃ZnC/Co/CNT composites with hollow structures have been synthesized through in-situ polymerization and high-temperature carbonization. The unique integration of low-dimensional nanostructures and multicomponent heterointerfaces confers exceptional EM absorption properties, achieving a reflection loss of −70.0 dB and significantly reducing radar cross section (RCS) scattering signals. It is particularly meaningful that the numerical simulation of Co₃ZnC/Co/CNT metamaterial reveals ultrawideband absorption performance, achieving 10.7 GHz (7.3–18.0 GHz) at a thickness of 4.5 mm and extending to 15 GHz (3.0–18.0 GHz) with a 10.5 mm. Moreover, the Co₃ZnC/Co/CNT composites retain meritorious EM absorption properties after flexible film formation, broadening their usability and application scope. These investigations will provide seminal insights encompassing theoretical validation, experimental synthesis, and practical application for the next generation of absorbers.