title: Constraint on the potassium content for the superconductivity of potassium-intercalated phenanthrene.
abstract: Raman-scattering measurements were performed on K(x)phenanthrene (0 ⩽ x ⩽ 6.0) at room temperature. Three phases (x = 3.0, 3.5, and 4.0) are identified based on the obtained Raman spectra. Only the K3phenanthrene phase is found to exhibit the superconducting transition at 5 K. The C-C stretching modes are observed to broaden and become disordered in K(x)phenanthrene with x = 2.0, 2.5, 6.0, indicating some molecular disorder in the metal intercalation process. This disorder is expected to influence the nonmetallic nature of these materials. The absence of metallic character in these nonsuperconducting phases is found from the calculated electronic structures based on the local density approximation.
authors.affiliation: Center for High Pressure Science and Technology Advanced Research, Shanghai 201203, China.
authors.forename: Qiao-Wei
authors.initials: QW
authors.lastname: Huang
authors.affiliation: Center for Photovoltaics and Solar Energy, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China.
authors.forename: Guo-Hua
authors.initials: GH
authors.lastname: Zhong
authors.affiliation: Department of Physics, South China University of Technology, Guangzhou 510640, China.
authors.forename: Jiang
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Center for High Pressure Science and Technology Advanced Research, Shanghai 201203, China.
authors.forename: Xiao-Miao
authors.initials: XM
authors.lastname: Zhao
authors.affiliation: Department of Physics, Yantai University, Yantai 264005, China.
authors.forename: Chao
authors.initials: C
authors.lastname: Zhang
authors.affiliation: Center for Photovoltaics and Solar Energy, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen 518055, China.
authors.forename: Hai-Qing
authors.initials: HQ
authors.lastname: Lin
authors.affiliation: Center for High Pressure Science and Technology Advanced Research, Shanghai 201203, China.
authors.forename: Xiao-Jia
authors.initials: XJ
authors.lastname: Chen