title: Superconductivity Series in Transition Metal Dichalcogenides by Ionic Gating.
abstract: Functionalities of two-dimensional (2D) crystals based on semiconducting transition metal dichalcogenides (TMDs) have now stemmed from simple field effect transistors (FETs) to a variety of electronic and opto-valleytronic devices, and even to superconductivity. Among them, superconductivity is the least studied property in TMDs due to methodological difficulty accessing it in different TMD species. Here, we report the systematic study of superconductivity in MoSe2, MoTe2 and WS2 by ionic gating in different regimes. Electrostatic gating using ionic liquid was able to induce superconductivity in MoSe2 but not in MoTe2 because of inefficient electron accumulation limited by electronic band alignment. Alternative gating using KClO4/polyethylene glycol enabled a crossover from surface doping to bulk doping, which induced superconductivities in MoTe2 and WS2 electrochemically. These new varieties greatly enriched the TMD superconductor families and unveiled critical methodology to expand the capability of ionic gating to other materials.
authors.affiliation: Quantum-Phase Electronics Center and Department of Applied Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan.
authors.forename: Wu
authors.initials: W
authors.lastname: Shi
authors.affiliation: 1] Quantum-Phase Electronics Center and Department of Applied Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan [2] Zernike Institute for Advanced Materials, University of Groningen, The Netherlands.
authors.forename: Jianting
authors.initials: J
authors.lastname: Ye
authors.affiliation: Quantum-Phase Electronics Center and Department of Applied Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan.
authors.forename: Yijin
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Quantum-Phase Electronics Center and Department of Applied Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan.
authors.forename: Ryuji
authors.initials: R
authors.lastname: Suzuki
authors.affiliation: Quantum-Phase Electronics Center and Department of Applied Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan.
authors.forename: Masaro
authors.initials: M
authors.lastname: Yoshida
authors.affiliation: Quantum-Phase Electronics Center and Department of Applied Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan.
authors.forename: Jun
authors.initials: J
authors.lastname: Miyazaki
authors.affiliation: Quantum-Phase Electronics Center and Department of Applied Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan.
authors.forename: Naoko
authors.initials: N
authors.lastname: Inoue
authors.affiliation: Quantum-Phase Electronics Center and Department of Applied Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan.
authors.forename: Yu
authors.initials: Y
authors.lastname: Saito
authors.affiliation: 1] Quantum-Phase Electronics Center and Department of Applied Physics, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-8656, Japan [2] Center for Emergent Matter Science, RIKEN, Hirosawa 2-1, Wako 351-0198, Japan.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Iwasa