Josephson coupled Ising pairing induced in suspended MoS2 bilayers by double-side ionic gating

• Published in: Nature nanotechnology Vol. 14; no. 12; pp. 1123 - 1128
• Main Authors: Zheliuk, O., Lu, J. M., Chen, Q. H., Yumin, A. A. El, Golightly, S., Ye, J. T.
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01-12-2019; Nature Publishing Group
• Subjects: 132/124; 142/126; 639/301/357/1018; 639/925/927/1064; Bilayers; Chalcogenides; Chemistry and Materials Science; Crossovers; Electron states; Gating; Interlayers; Ionic liquids; Ising model; Materials Science; Molybdenum disulfide; Nanotechnology; Nanotechnology and Microengineering; Spin-orbit interactions; Superconductivity; Symmetry; Transition metal compounds
• ISSN: 1748-3387; 1748-3395
• DOI: 10.1038/s41565-019-0564-1

Superconductivity in monolayer transition metal dichalcogenides is characterized by Ising-type pairing induced via a strong Zeeman-type spin–orbit coupling. When two transition metal dichalcogenides layers are coupled, more exotic superconducting phases emerge, which depend on the ratio of Ising-type protection and interlayer coupling strength. Here, we induce superconductivity in suspended MoS
2
bilayers and unveil a coupled superconducting state with strong Ising-type spin–orbit coupling. Gating the bilayer symmetrically from both sides by ionic liquid gating varies the interlayer interaction and accesses electronic states with broken local inversion symmetry while maintaining the global inversion symmetry. We observe a strong suppression of the Ising protection that evidences a coupled superconducting state. The symmetric gating scheme not only induces superconductivity in both atomic sheets but also controls the Josephson coupling between the layers, which gives rise to a dimensional crossover in the bilayer.
Transition metal dichalcogenide monolayers can host Ising-type superconductivity and if two such layers are coupled, exotic superconducting phases may emerge. Here, the authors induce a coupled superconducting state with tuneable Ising protection by means of symmetric, double-side ionic liquid gating.