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Transition metal dichalcogenide (TMD) monolayers, with their direct band gaps, have attracted wide attention from the fields of photonics and optoelectronics. However, monolayer semiconducting TMDs generally suffer from low excitation absorption and emission efficiency, limiting their further applications. Here a flip‐over plasmonic structure comprised of silver nano‐disk arrays supporting a WS2 monolayer sandwiched by hexagonal boron nitride (h‐BN) layers is demonstrated. The flip‐over configuration optimizes the optical process with a free excitation/emission path from the top and a strong plasmonic interaction from the bottom. As a result, the photoluminescence from the TMD monolayers can be greatly enhanced more than tenfold by optimizing the metasurface, which can be further improved nearly tenfold by optimizing the thickness of bottom h‐BN. This study shows the advantages of using the flip‐over structure, where the plasmonic interaction between the metasurface and TMDs can be tuned by introducing optimized plasmonic arrays and h‐BN layers with suitable thickness. This hybrid device configuration paves a reliable platform to study the light–matter interaction, achieving highly efficient plasmonic TMD devices. [ABSTRACT FROM AUTHOR]

The strong spin–orbit coupling along with broken inversion symmetry in transition metal dichalcogenides (TMDs) results in spin polarized valleys, which are the origins of many interesting properties such as Ising superconductivity, circular dichroism, valley Hall effect, etc. Herein, it is shown that encapsulating few‐layer MoS2 between hexagonal boron nitride (h‐BN) and gating the electrical contacts by ionic liquid pronounce Shubnikov–de Haas (SdH) oscillations in magnetoresistance. Notably, the SdH oscillations remain unchanged in tilted magnetic fields, demonstrating that the spins of the Q/Q′ valleys are firmly locked to the out‐of‐plane direction; therefore, Zeeman energy is insensitive to the in‐plane magnetic field. Ionic liquid gating induces superconductivity on the surface of unencapsulated MoS2. The spins of Cooper pairs are strongly pinned to the out‐of‐plane direction by the effective Zeeman field, hence are protected from being realigned by an in‐plane magnetic field, namely, Ising protection. As a result, superconductivity persists in an in‐plane magnetic field up to 14 T, in which Tc only decreases by ≈0.3 K from Tc0 as ≈7 K. By applying back gate, the strength of Ising protection can be effectively tuned, where an increase in 70% is observed when back gate changes from +90 to −90 V. [ABSTRACT FROM AUTHOR]

The strong spin–orbit coupling along with broken inversion symmetry in transition metal dichalcogenides (TMDs) results in spin polarized valleys, which are the origins of many interesting properties such as Ising superconductivity, circular dichroism, valley Hall effect, etc. Herein, it is shown that encapsulating few‐layer MoS2 between hexagonal boron nitride (h‐BN) and gating the electrical contacts by ionic liquid pronounce Shubnikov–de Haas (SdH) oscillations in magnetoresistance. Notably, the SdH oscillations remain unchanged in tilted magnetic fields, demonstrating that the spins of the Q/Q′ valleys are firmly locked to the out‐of‐plane direction; therefore, Zeeman energy is insensitive to the in‐plane magnetic field. Ionic liquid gating induces superconductivity on the surface of unencapsulated MoS2. The spins of Cooper pairs are strongly pinned to the out‐of‐plane direction by the effective Zeeman field, hence are protected from being realigned by an in‐plane magnetic field, namely, Ising protection. As a result, superconductivity persists in an in‐plane magnetic field up to 14 T, in which Tc only decreases by ≈0.3 K from Tc0 as ≈7 K. By applying back gate, the strength of Ising protection can be effectively tuned, where an increase in 70% is observed when back gate changes from +90 to −90 V. [ABSTRACT FROM AUTHOR]