Metallic ferromagnetic selenospinel composites of CuCr2Se4-CdCr2Se4 with double negative electromagnetic parameters

Random metamaterial with negative electric permittivity (epsilon<0) and negative magnetic permeability (mu<0) is a group of attractive alternatives to ordered double negative metamaterials (DNMs) with periodic unit cells; however, the preparation of random DNMs with a relatively convenient preparation process and their electromagnetic property adjustment are of challenge. Here, we report the preparation of metallic ferromagnetic selenospinel composites, xCdCr(2)Se(4)(1-x)CuCr2Se4, from metallic powders by using a simple solid-state reaction process, and double negative epsilon and mu have been observed in the frequency range of 120-650MHz for 0.2CdCr(2)Se(4)0.8CuCr(2)Se(4) and 73-520MHz for 0.4CdCr(2)Se(4)0.6CuCr(2)Se(4). The negative epsilon is owing to the plasmonic state of delocalized carriers in the metallic ferromagnetic CuCr2Se4, which can be described with the Drude model. The suppression of the magnetic resonance induced by the eddy current has been alleviated by the proper addition of the paramagnetic semiconductor CdCr2Se4. A theoretical model deduced from Maxwell's equation has been constructed based on the skin effect to elucidate the magnetic resonance-dependent negative permeability. Our work introduces the metallic ferromagnetic chalcospinels into the field of random DNMs and sheds light on the theoretical understanding and tuning mechanism on the double negative properties.

Automated summary

This study reports the preparation of metallic ferromagnetic selenospinel composites using a solid-state reaction process, successfully demonstrating double negative properties with negative electric permittivity and negative magnetic permeability. The research provides theoretical insights and mechanisms for understanding and tuning the properties of double negative metamaterials.