期刊
NANO LETTERS
卷 18, 期 8, 页码 4821-4830出版社
AMER CHEMICAL SOC
DOI: 10.1021/acs.nanolett.8b01390
关键词
Transition metal dichalcogenides; ionic gating; superconductivity; electron-phonon coupling; Raman spectroscopy; Lifshitz transitions
类别
资金
- EU Graphene Flagship
- ERC Grant Hetero2D
- EPSRC [EP/509 K01711X/1, EP/K017144/1, EP/N010345/1, EP/M507799/5101, EP/L016087/1]
- Joint Project for the Internationalization of Research 2015 by Politecnico di Torino and Compagnia di San Paolo
- EPSRC [EP/K017144/1, EP/N010345/1, EP/K01711X/1] Funding Source: UKRI
Layers of transition metal dichalcogenides (TMDs) combine the enhanced effects of correlations associated with the two-dimensional limit with electrostatic control over their phase transitions by means of an electric field. Several semiconducting TMDs, such as MoS2, develop superconductivity (SC) at their surface when doped with an electrostatic field, but the mechanism is still debated. It is often assumed that Cooper pairs reside only in the two electron pockets at the K/K' points of the Brillouin Zone. However, experimental and theoretical results suggest that a multivalley Fermi surface (FS) is associated with the SC state, involving six electron pockets at Q/Q'. Here, we perform low-temperature transport measurements in ion-gated MoS2 flakes. We show that a fully multivalley FS is associated with the SC onset. The Q/Q' valleys fill for doping greater than or similar to 2 X 10(13) cm(-2) , and the SC transition does not appear until the Fermi level crosses both spin-orbit split sub-bands Q(1) and Q(2). The SC state is associated with the FS connectivity and promoted by a Lifshitz transition due to the simultaneous population of multiple electron pockets. This FS topology will serve as a guideline in the quest for new superconductors.
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