The Zeeman effect, which is usually detrimental to superconductivity, can be strongly protective when an effective Zeeman field from intrinsic spin-orbit coupling locks the spins of Cooper pairs in a direction orthogonal to an external magnetic field. We performed magnetotransport experiments with ionic-gated molybdenum disulfide transistors, in which gating prepared individual superconducting states with different carrier dopings, and measured an in-plane critical field B(c2) far beyond the Pauli paramagnetic limit, consistent with Zeeman-protected superconductivity. The gating-enhanced B(c2) is more than an order of magnitude larger than it is in the bulk superconducting phases, where the effective Zeeman field is weakened by interlayer coupling. Our study provides experimental evidence of an Ising superconductor, in which spins of the pairing electrons are strongly pinned by an effective Zeeman field.

Many recent studies show that superconductivity not only exists in atomically thin monolayers but can exhibit enhanced properties such as a higher transition temperature and a stronger critical field. Nevertheless, besides being unstable in air, the weak tunability in these intrinsically metallic monolayers has limited the exploration of monolayer superconductivity, hindering their potential in electronic applications (e.g., superconductor-semiconductor hybrid devices). Here we show that using field effect gating, we can induce superconductivity in monolayer WS grown by chemical vapor deposition, a typical ambient-stable semiconducting transition metal dichalcogenide (TMD), and we are able to access a complete set of competing electronic phases over an unprecedented doping range from band insulator, superconductor, to a reentrant insulator at high doping. Throughout the superconducting dome, the Cooper pair spin is pinned by a strong internal spin-orbit interaction, making this material arguably the most resilient superconductor in the external magnetic field. The reentrant insulating state at positive high gating voltages is attributed to localization induced by the characteristically weak screening of the monolayer, providing insight into many dome-like superconducting phases observed in field-induced quasi-2D superconductors.

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Engineering the properties of quantum electron systems, e.g., tuning the superconducting phase using low driving bias within an easily accessible temperature range, is of great interest for exploring exotic physical phenomena as well as achieving real applications. Here, the realization of continuous field-effect switching between superconducting and non-superconducting states in a few-layer MoS transistor is reported. Ionic-liquid gating induces the superconducting state close to the quantum critical point on the top surface of the MoS , and continuous switching between the super/non-superconducting states is achieved by HfO back gating. The superconducting transistor works effectively in the helium-4 temperature range and requires a gate bias as low as ≈10 V. The dual-gate device structure and strategy presented here can be easily generalized to other systems, opening new opportunities for designing high-performance 2D superconducting transistors.

Graphene moiré superlattice formed by rotating two graphene sheets can host strongly correlated and topological states when flat bands form at so-called magic angles. Here, we report that, for a twisting angle far away from the magic angle, the heterostrain induced during stacking heterostructures can also create flat bands. Combining a direct visualization of strain effect in twisted bilayer graphene moiré superlattices and transport measurements, features of correlated states appear at “non-magic” angles in twisted bilayer graphene under the heterostrain. Observing correlated states in these “non-standard” conditions can enrich the understanding of the possible origins of the correlated states and widen the freedom in tuning the moiré heterostructures and the scope of exploring the correlated physics in moiré superlattices.

Superconductivity in monolayer tungsten disulfide (2H‐WS2) is achieved by strong electrostatic electron doping of an electric double‐layer transistor (EDLT). Single crystals of WS2 are grown by a scalable method − chemical vapor deposition (CVD) on standard Si/SiO2 substrate. The monolayers are identified by both AFM and color‐coding techniques. The EDLT device based on single‐layer WS2 shows ambipolar transfer characteristics indicating a semiconducting nature of the material. Metallic transport on the electron side evolves into superconductivity with critical temperature Tc = 3.15 K.

Transition metal dichalcogenides (TMDs) are attracting growing interest for their prospective application in electronic and optical devices. As a leading material in researches of two‐dimensional (2D) electronics, although band structure is layer‐dependent, the TMDs show ambipolar properties. While optically excited light emission has been widely investigated, study on electrically generated emission is still limited. Taking the advantage of its ambipolarity and presence of direct band‐gap in monolayer, we developed an electrically driven light emitting device based on stacked 2D flakes to obtain sharp planar p–n junction in monolayer. Specifically, we have fabricated atomic‐layer TMDs/boron nitride (BN) artificial heterostructures using stacked h‐BN thin flake as a mask to partially cover the TMDs transistor channel allowing high‐density hole accumulation (p‐region) via localized exposure to gate‐controlled accumulation of anions. Transport through the junction shows typical diode‐like rectification current with accompanying strong and sharp light emission from the crystal edge of BN mask for the monolayer case.