Percolated cermets of nickel/yttrium iron garnet for double negative metacomposites

Dielectric and magnetic properties of percolative nickel/yttrium iron garnet cermets were investigated. With nickel content increasing, microstructure evolution of the cermets exhibited characteristics of percolation , resulting in electrical conductivity increased dramatically and conduction mechanism changed from hopping to metallic behaviors. Negative permittivity and negative permeability were observed. Negative permittivity was caused by the plasmonic state of delocalized electrons. Negative permeability was attributed to magnetic resonance of ferromagnetic constituents and diamagnetic responses of eddy currents induced in interconnected nickel networks. The obtained double negative metacomposites enriched metamaterials and have great potential in electromagnetic shielding, cloaking, and attenuation applications.