Temperature‐Induced Self‐Decomposition Doping of Fe3GeTe2 to Achieve Ultra‐High Tc of 496 K for Multispectral Compatible Strong Electromagnetic Wave Absorption

Fe3GeTe2 provides an ideal system for the study of itinerant ferromagnetism. However, the Curie temperature (Tc) below room temperature limits its further in‐depth research and wide applications. Here, the Tc of 224 K for Fe3GeTe2 is greatly increased to 496 K for Fe3GeTe2/FeTe2/Fe3Ge by temperature‐induced self‐decomposition doping, contributing to improve the electromagnetic response for enhancing the absorption strength and bandwidth and boosting application potentials at higher temperatures. Then, to achieve the multispectral compatible strong absorption, room temperature ferromagnetic dielectric graphene@Fe3GeTe2/FeTe2/Fe3Ge absorber with 3D porous network structure is prepared by synergistic self‐assembly. It has high Tc of 443 K with strong electromagnetic synergistic loss, achieving reflection loss of −61 dB at 12.6 GHz. Moreover, its absorption loss in the terahertz band (0.1–1.6 THz) is 76 dB, and the average loss is greater than 50.4 dB. Furthermore, the absorber is very potential as stealth skin to efficiently reduce satellite RCS with a multi‐angle and multi‐band manner in the gigahertz and terahertz bands, thus achieving the purpose of stealth. Compared with the reported conventional absorbers, the absorber has a multispectral compatible strong absorption performance covering gigahertz and terahertz bands, thus very promising for electromagnetic protection of electromagnetic communication and space vehicles. The Curie temperature of Fe3GeTe2 is greatly increased from 224 to 496 K by temperature‐induced self‐decomposition doping to improve electromagnetic response. Then, dielectric graphene and Fe3GeTe2 are synergistic self‐assembled into the dielectric/magnetic coupling absorber with strong electromagnetic synergistic loss to achieve multispectral compatible strong absorption covering gigahertz and terahertz bands with broadband RCS reduction at multi‐angle and multi‐frequency.