Broadband Microwave Absorption and Adaptable Multifunctionality of Carbonaceous Chiral Metamaterials under Deep Subwavelength Thickness

Developing microwave absorption materials with broad absorption bandwidth and adaptive multifunctionality is considerably attractive for practical applications. However, achieving broadband absorption under deep-subwavelength thickness in carbonaceous materials without magnetic elements remains a challenge. Herein, ferromagnetic carbonaceous chiral metamaterials (CCMs) were innovatively manufactured for achieving microwave absorption, without loading any magnetic elements. The ferromagnetism of carbon materials was obtained by eliminating the C–H bond that is destructive to the exchange interaction in carbon materials. Through a one-step carbonization process, the chiral gyrotropic metastructures further induced helical current to enhance magnetic loss according to Faraday’s law and the symmetry breaking principle. As a result, the widest absorption bandwidth experimentally achieved by the CCMs was 7.52 GHz (reflection loss ≤ −7 dB) and 4.92 GHz (reflection loss ≤ −10 dB) under a deep-subwavelength thickness of 1.5 mm. The CCMs also have adaptive multifunctionality such as corrosion resistance and high-temperature resistance as well as good flexibility and are ultralightweight. These phenomena and mechanisms suggest a paradigm of magnetic loss generated by nonferromagnetic materials to realize broadband microwave absorption, in which their adaptive multifunctionality may lead to integrated applications of microwave absorption materials under a harsh environment.