Microscopic Response Mechanism of Epsilon-Negative and Epsilon-Near-Zero Metacomposites
Yunlei Zhou, Yanan Wang, Shicheng Qiu, Wei Zhao, Shaolei Wang, Hong Bao, Yunpeng Qu, Zhen Wen
Abstract
Metals have traditionally served as the primary functional phase in the development of metamaterials exhibiting epsilon-near-zero (ENZ) and epsilon-negative (EN) responses, albeit with persisting ambiguities regarding their response mechanisms. This paper presents the tunable ENZ ( ε ′ ~ 0) and EN ( ε ′ < 0) parameters at the 20-MHz to 1-GHz region based on Cu/CaCu 3 Ti 4 O 12 (Cu/CCTO) metacomposites. By means of first-principles calculations and multi-physics simulations, the underlying mechanisms governing ENZ and EN responses are unveiled. The intricate pathways through which metacomposites achieve 2 dielectric response mechanisms are delineated: At low Cu content, a weak EN response (| ε ′| < 200) was excited by electric dipole resonance, accompanied by ENZ effect; conversely, at high Cu content, due to the increase in effective electron concentration, plasmonic oscillation behavior occurs in the constructed 3-dimensional Cu network, resulting in strong EN response (| ε ′| ~ 1,000) in the radio frequency band. These phenomena are explicated through 2 distinct Cu/CCTO models: Cu in an isolated state and a connected network state. This study not only comprehensively elucidates the 2 EN response mechanisms achieved by typical metacomposites with metals as functional phases but also delves into their associated electromagnetic shielding and thermal properties, providing a theoretical basis for their practical applications.