Discovery of Superconductivity in 2M WS2 with Possible Topological Surface States

Abstract Recently the metastable 1T′‐type VIB‐group transition metal dichalcogenides (TMDs) have attracted extensive attention due to their rich and intriguing physical properties, including superconductivity, valleytronics physics, and topological physics. Here, a new layered WS 2 dubbed “2M” WS 2 , is constructed from 1T′ WS 2 monolayers, is synthesized. Its phase is defined as 2M based on the number of layers in each unit cell and the subordinate crystallographic system. Intrinsic superconductivity is observed in 2M WS 2 with a transition temperature T c of 8.8 K, which is the highest among TMDs not subject to any fine‐tuning process. Furthermore, the electronic structure of 2M WS 2 is found by Shubnikov–de Haas oscillations and first‐principles calculations to have a strong anisotropy. In addition, topological surface states with a single Dirac cone, protected by topological invariant Z 2 , are predicted through first‐principles calculations. These findings reveal that the new 2M WS 2 might be an interesting topological superconductor candidate from the VIB‐group transition metal dichalcogenides.