  Layered metal chalcogenide materials provide a versatile platform to
investigate emergent phenomena and two-dimensional (2D) superconductivity
at/near the atomically thin limit. In particular, gate-induced interfacial
superconductivity realized by the use of an electric-double-layer transistor
(EDLT) has greatly extended the capability to electrically induce
superconductivity in oxides, nitrides and transition metal chalcogenides and
enable one to explore new physics, such as the Ising pairing mechanism.
Exploiting gate-induced superconductivity in various materials can provide us
with additional platforms to understand emergent interfacial superconductivity.
Here, we report the discovery of gate-induced 2D superconductivity in layered
1T-SnSe2, a typical member of the main-group metal dichalcogenide (MDC) family,
using an EDLT gating geometry. A superconducting transition temperature Tc
around 3.9 K was demonstrated at the EDL interface. The 2D nature of the
superconductivity therein was further confirmed based on 1) a 2D Tinkham
description of the angle-dependent upper critical field, 2) the existence of a
quantum creep state as well as a large ratio of the coherence length to the
thickness of superconductivity. Interestingly, the in-plane approaching zero
temperature was found to be 2-3 times higher than the Pauli limit, which might
be related to an electric field-modulated spin-orbit interaction. Such results
provide a new perspective to expand the material matrix available for
gate-induced 2D superconductivity and the fundamental understanding of
interfacial superconductivity.
