  Recently, intriguing phenomena of superconductivity, type-II Weyl semimetal
or quantum spin Hall states were discovered in metastable 1T'-type VIB-group
transition metal dichalcogenides (TMDs). Here, we report that monoclinic phase
WS2 was discovered and synthesized in our experiments. The intrinsic
superconducting transition was observed in monoclinic WS2 with a transition
temperature Tc of 8.8 K which is the highest among previously reported TMDs
without any fine-tuning process. Intersteing, topological insulator state,
defined by topological invariant Z2, was also discovered with a single Dirac
cone on the surface, which is different from all topological states reported in
TMDs. Further, the electronic structure was found to have a strong anisotropy
by Shubnikov-de Haas oscillations and first-principles calculations. Our
findings reveal that monoclinic WS2 might be a new topological
superconductivity candidate with a strong anisotropy.
