Superconductivity in twisted bilayer WSe2

Moir & eacute; materials have enabled the realization of flat electron bands and quantum phases that are driven by the strong correlations associated with flat bands1-4. Superconductivity has been observed, but only in graphene moir & eacute; materials5-9. The absence of robust superconductivity in moir & eacute; materials beyond graphene, such as semiconductor moir & eacute; materials4, has remained a mystery and challenged our current understanding of superconductivity in flat bands. Here we report the observation of robust superconductivity in both 3.5 degrees and 3.65 degrees twisted bilayer tungsten diselenide (WSe2), which hosts a hexagonal moir & eacute; lattice10,11. Superconductivity emerges near half-band filling and zero external displacement fields. The optimal superconducting transition temperature is about 200 mK in both cases and constitutes about 1-2% of the effective Fermi temperature; the latter is comparable to the value in high-temperature cuprate superconductors12 and suggests strong pairing. The superconductor borders on two distinct metals below and above half-band filling; it undergoes a continuous transition to a correlated insulator by tuning the external displacement field. The observed superconductivity on the verge of Coulomb-induced charge localization suggests roots in strong electron correlations12,13. Robust superconductivity is observed in twisted bilayer tungsten diselenide (WSe2) on the verge of Coulomb-induced charge localization around half-band filling and zero external displacement fields.