title: Emergence of superconductivity in (NH3)yMxMoSe2 (M: Li, Na and K).
abstract: We report syntheses of new superconducting metal-doped MoSe2 materials (MxMoSe2). The superconducting MxMoSe2 samples were prepared using a liquid NH3 technique, and can be represented as '(NH3)yMxMoSe2'. The Tcs of these materials were approximately 5.0 K, independent of x and the specific metal atom. X-ray diffraction patterns of (NH3)yNaxMoSe2 were recorded using polycrystalline powders. An increase in lattice constant c showed that the Na atom was intercalated between MoSe2 layers. The x-independence of c was observed in (NH3)yNaxMoSe2, indicating the formation of a stoichiometric compound in the entire x range, which is consistent with the x-independence of Tc. A metallic edge of the Fermi level was observed in the photoemission spectrum at 30 K, demonstrating its metallic character in the normal state. Doping of MoSe2 with Li and K also yielded superconductivity. Thus, MoSe2 is a promising material for designing new superconductors, as are other transition metal dichalcogenides.
authors.affiliation: Research Laboratory for Surface Science, Okayama University, Okayama 700-8530, Japan.
authors.forename: Xiao
authors.initials: X
authors.lastname: Miao
authors.affiliation: Research Laboratory for Surface Science, Okayama University, Okayama 700-8530, Japan.
authors.forename: Saki
authors.initials: S
authors.lastname: Nishiyama
authors.affiliation: Research Laboratory for Surface Science, Okayama University, Okayama 700-8530, Japan.
authors.forename: Lu
authors.initials: L
authors.lastname: Zheng
authors.affiliation: Research Laboratory for Surface Science, Okayama University, Okayama 700-8530, Japan.
authors.forename: Hidenori
authors.initials: H
authors.lastname: Goto
authors.affiliation: Research Laboratory for Surface Science, Okayama University, Okayama 700-8530, Japan.
authors.forename: Ritsuko
authors.initials: R
authors.lastname: Eguchi
authors.affiliation: Advanced Science Research Centre, Okayama University, Okayama 700-8530, Japan.
authors.forename: Hiromi
authors.initials: H
authors.lastname: Ota
authors.affiliation: Department of Physics, Okayama University, Okayama 700-8530, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Kambe
authors.affiliation: Research Laboratory for Surface Science, Okayama University, Okayama 700-8530, Japan.
authors.forename: Kensei
authors.initials: K
authors.lastname: Terashima
authors.affiliation: Research Laboratory for Surface Science, Okayama University, Okayama 700-8530, Japan.|Research Centre of New Functional Materials for Energy Production, Storage and Transport, Okayama University, Okayama 700-8530, Japan.
authors.forename: Takayoshi
authors.initials: T
authors.lastname: Yokoya
authors.affiliation: Centre for Science and Technology under Extreme Conditions, Osaka University, Osaka 560-8531, Japan.
authors.forename: Huyen T L
authors.initials: HT
authors.lastname: Nguyen
authors.affiliation: Centre for Science and Technology under Extreme Conditions, Osaka University, Osaka 560-8531, Japan.
authors.forename: Tomoko
authors.initials: T
authors.lastname: Kagayama
authors.affiliation: SPring-8/JASRI, Hyogo 679-5198, Japan.
authors.forename: Naohisa
authors.initials: N
authors.lastname: Hirao
authors.affiliation: SPring-8/JASRI, Hyogo 679-5198, Japan.
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Ohishi
authors.affiliation: National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan.
authors.forename: Hirofumi
authors.initials: H
authors.lastname: Ishii
authors.affiliation: National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan.
authors.forename: Yen-Fa
authors.initials: YF
authors.lastname: Liao
authors.affiliation: Research Laboratory for Surface Science, Okayama University, Okayama 700-8530, Japan.|Research Centre of New Functional Materials for Energy Production, Storage and Transport, Okayama University, Okayama 700-8530, Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Kubozono