材料科学
介电常数
碳纳米管
电介质
光电子学
磁场
凝聚态物理
无线电频率
纳米技术
电气工程
物理
工程类
量子力学
作者
Kai Sun,Chong Wang,Jiahong Tian,Zheng Zhang,Ni Zeng,Rui Yin,Wenxin Duan,Qing Hou,Yaman Zhao,Haikun Wu,Runhua Fan
标识
DOI:10.1002/adfm.202306747
摘要
Abstract Epsilon‐near‐zero (ENZ) materials, exhibiting unique physical characteristics such as near‐zero refraction, have aroused extensive interest and exhibit great potentials in novel applications of perfect absorbers, high‐harmonic generation, and nonlinear optical response. Here, for the first time, magnetic‐driven broadband ENZ materials are designed by fabricating polyvinyl alcohol (PVA)/Ni@carbon nanotubes (CNTs) films. Dielectric properties including real permittivity ( ɛ ′), imaginary permittivity ( ɛ ″), dielectric loss (tan δ ), and impedance ( Z ) are investigated. When Ni@CNTs content reached 30 wt.%, negative permittivity transferred to positive permittivity at ≈11.5 MHz, and epsilon‐near‐zero (| ɛ ′| < 1) is realized from ≈9 to 14 MHz, exhibiting broad ENZ bandwidth of ≈5 MHz. Theory calculations confirm that delocalized electrons are introduced from CNTs, which improve the carrier mobility and achieve low frequency dispersion behavior. Longer interfacial polarization electric fields between PVA and CNTs are also demonstrated by theory calculations, enhancing the positive permittivity response to offset negative permittivity response from Ni@CNTs. These two mechanisms result in broadband ENZ at radio frequency. This film also exhibits excellent magnetic actuation ability under magnetic field, broadening applications from ENZ materials to novel fields such as magnetically actuated robots with perfect absorption, magnetic‐driven biomimetic aircrafts with shielding ability, magnetic‐driven photodetectors, etc.
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