Communication—Tunable and Weakly Epsilon-Negative Property Realized by Metallic Granular Metacomposites at Radio-Frequency Region

We fabricated metallic granular metacomposites by low-temperature pressureless sintering. A percolation behavior appears, corresponding to the observation of metal-like conductivity and epsilon-negative. Weakly epsilon-negative property is achieved in 70 wt% FeCrNi/CaCu3Ti4O12 metacomposites, showing small absolute value of epsilon between 0 and −150. The epsilon-negative property is tuned by adjusting metal content in metacomposites and high negative value of real permittivity (∼−104) is achieved. The superposition of Lorentz and Drude model explains the radio-frequency (RF) epsilon-negative. Epsilon-negative property correlates with inductive character as investigated by equivalent circuit analysis. Our work benefits the practical applications of epsilon-negative property in electromagnetic fields.