title: Low-loss terahertz metamaterial from superconducting niobium nitride films.
abstract: This paper reports a type of low Ohmic loss terahertz (THz) metamaterials made from low-temperature superconducting niobium nitride (NbN) films. Its resonance properties are studied by THz time domain spectroscopy. Our experiments show that its unloaded quality factor reaches as high as 178 at 8 K with the resonance frequency at around 0.58 THz, which is about 24 times that of gold metamaterial at the same temperature. The unloaded quality factor keeps at a high level, above 90, even when the resonance frequency increases to 1.02 THz, which is close to the gap frequency of NbN film. All these experimental observations fit well into the framework of Bardeen-Copper-Schrieffer theory and equivalent circuit model. These new metamaterials offer an efficient way to the design and implementation of high performance THz electronic devices.
authors.affiliation: Research Institute of Superconductor Electronics, School of Electronic Science and Engineering, Nanjing University, Nanjing 210093, China.
authors.forename: C H
authors.initials: CH
authors.lastname: Zhang
authors.forename: J B
authors.initials: JB
authors.lastname: Wu
authors.forename: B B
authors.initials: BB
authors.lastname: Jin
authors.forename: Z M
authors.initials: ZM
authors.lastname: Ji
authors.forename: L
authors.initials: L
authors.lastname: Kang
authors.forename: W W
authors.initials: WW
authors.lastname: Xu
authors.forename: J
authors.initials: J
authors.lastname: Chen
authors.forename: M
authors.initials: M
authors.lastname: Tonouchi
authors.forename: P H
authors.initials: PH
authors.lastname: Wu
mesh_terms: D004553:Electric Conductivity; D008422:Materials Testing; D008567:Membranes, Artificial; D009556:Niobium / Q000737:chemistry*; D009584:Nitrogen / Q000737:chemistry; D012031:Refractometry; D012542:Scattering, Radiation; D055053:Terahertz Radiation
chemical_list: D008567:Membranes, Artificial; D009556:Niobium; D009584:Nitrogen