Ingenious microstructure combination through topological surface state enabled MnBi2Te4/carbon fibers to be an ultrathin absorber

Topological insulators exhibit great attraction in the fields of spintronics and quantum anomalous Hall effect, but their interaction with electromagnetic waves is rarely explored. Herein, topological insulator MnBi2Te4, synthesized via a solid-phase melting approach, was employed to compound with conductive materials. Benefiting from the unique topological untrivial property embodied in conductive topological surface state and ingenious composite microstructure, MnBi2Te4/carbon fibers displayed an efficient conductive network and high permittivity, obtaining an ultrathin electromagnetic wave absorption capacity with a maximum effective absorbing bandwidth of 2.6 GHz at 0.9 mm and a minimum reflection loss of −38.4 dB at 1.2 mm. More importantly, its effective absorbing peaks can cover 2–18 GHz through regulating its thickness, ranging from 0.8 to 6 mm. It is deciphered that topological insulators can retain the conductivity from conductive materials to a great extent and achieve distinct performances by compositing with materials of various microstructures. This work provides valuable insights into utilizing the unique advantages of topological insulators through compositing strategy and presents a precious approach for electromagnetic wave–absorbing composite materials.