The negative permittivity behavior of carbon nanotubes/yttrium iron garnet composites in the radio frequency

The composites with negative permittivity have drawn intensive attentions due to their promising candidates for double negative materials (DNMs). In this work, dielectric properties of the carbon nanotubes/yttrium iron garnet (CNTs/YIG) composites with different CNTs content have been researched in radio frequency. When CNTs content exceeds percolation threshold, the CNTs interconnect with each other and form conductive networks. Then the negative permittivity is obtained and can be attributed to the motion of charge carriers along the CNTs networks in the CNTs/YIG composites. In addition, with CNTs content raising, the gradually electron densities result in effective adjustment of negative permittivity in different frequency ranges. Therefore, the CNTs/YIG composites with tunable negative permittivity have great potential to be DNMs.