Correlated States in Twisted Bilayer WSe₂at Integer and Fractional Charges per Moiré Unit Cell

The discovery of flat bands in magic-angle twisted bilayer graphene (MATBG) opened a new field of correlated physics research, revealing correlated insulating phases and superconductivity. Similar to MATBG, moiré systems based on transition metal dichalcogenides (TMDs) such as twisted MoTe₂ and WSe₂, can host flat bands over a wider range of twist angles. Here we investigate the transport characteristics in small-angle twisted bilayer WSe₂, with twist angles between 2˚ and 3˚. Our devices feature a dual-gate structure with graphite gates, which enables independent control of the carrier density and the displacement field. Remarkably, at zero magnetic field we observe signatures of correlated states when the number of carriers per moiré unit cell (ν) is integer, for ν = 2 and ν = 3, as well as fractional, for ν = 5/3, 7/3, 8/3.  The correlated states at fractional ν survive up to 5 K, while the correlated states at integer ν survive up to 20 K.