Electrostatically Induced Superconductivity at the Surface of WS${}_2$

Abstract

We investigate transport through ionic liquid gated field effect transistors (FETs) based on exfoliated crystals of semiconducting WS${}_2$. Upon electron accumulation, at surface densities close to -or just larger than- 10${}^{14}$ cm${}^{-2}$, transport exhibits metallic behavior, with the surface resistivity decreasing pronouncedly upon cooling. A detailed characterization as a function of temperature and magnetic field clearly shows the occurrence of a gate-induced superconducting transition below a critical temperature $T_c\approx 4$ K, a finding that represents the first demonstration of superconductivity in tungsten-based semiconducting transition metal dichalcogenides. We investigate the nature of superconductivity and find significant inhomogeneity, originating from the local detaching of the frozen ionic liquid from the WS${}_2$ surface. Despite the inhomogeneity, we find that in all cases where a fully developed zero resistance state is observed, different properties of the devices exhibit a behavior characteristic of a Berezinskii-Kosterlitz-Thouless transition, as it could be expected in view of the two-dimensional nature of the electrostatically accumulated electron system.

18 pages, 4 figures; Nano Letters (2015)

References in corpus (6)

• Valley polarization in MoS2 monolayers by optical pumping
• The Valley Hall Effect in MoS2 Transistors
• Electrical Transport Properties of Single-Layer WS2
• Quantitative Determination of the Band-Gap of WS2 with Ambipolar Ionic Liquid-Gated Transistors
• Mono- and Bilayer WS2 Light-Emitting Transistors
• Scanning photocurrent microscopy reveals electron-hole asymmetry in ionic liquid-gated WS2 transistors

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• Gated Tuned Superconductivity and Phonon Softening in Mono- and Bilayer MoS${}_2$
• Superconductivity in monolayer Ba${}_2$N electride: a first-principles study
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• Ionic gating in metallic superconductors: A brief review
• Full control of solid-state electrolytes for electrostatic gating
• Temperature effect on lattice and electronic structures of WTe${}_2$ from first-principles study
• Strong band-filling-dependence of the scattering lifetime in gated MoS2 nanolayers induced by the opening of intervalley scattering channels
• Anomalous metallic phase in molybdenum disulphide induced via gate-driven organic ion intercalation