Super magnetic loss induced by tunable damping coefficient through Ni nanoparticles size matching in magnetic carbon

Abstract

For dielectric-magnetic dual loss absorbers, magnetic loss capacity is the main contributor for improving microwave absorbing performances. Shape anisotropy induced by different morphologies and large out-of-plane anisotropy field in the material system are main common strategies to increase magnetic loss ability. We herein propose a new idea for enhancing magnetic loss capacity induced by tunable damping coefficient through Ni particle-size matching in magnetic carbon nanocomposites. As an example, for annealed magnetic carbon at 700 °C, it delivers imaginary part of permeability up to 0.462 and super magnetic loss of 0.6, resulting in minimal reflection loss of −41.91 dB at absorbing layer thickness of 3.4 mm and efficient absorbing bandwidth of 4.24 GHz at absorbing layer thickness of 2.9 mm. By applying the combination of Gilbert equation and effective medium theory, the effective permeability calculations reveals that the significant enhancement originates from the tunable damping coefficient through Ni particles size matching. The relationship model between damping coefficient and size matching has been proposed, which is well consistent with experimental data. This work is of great significance for understanding the physical process of particle size matching to strengthen electromagnetic loss ability, and provides an alternative for the design of electromagnetic absorbing materials with strong magnetic loss ability.