Correlated insulating states in slow Dirac fermions on a honeycomb moiré superlattice.

Strong Coulomb repulsion is predicted to open a many-body charge gap at graphene's Dirac point, transforming the semimetal into a Mott insulator. However, this correlated insulating phase remains elusive in pristine graphene, where the large Fermi velocity dominates interactions. To overcome this limitation, we realize a honeycomb moiré superlattice in twisted MoSe2 homobilayers, where a graphene-like band structure forms with a Fermi velocity reduced by nearly two orders of magnitude. These slow moiré bands, folded from the valence band maximum at the Γ valley with negligible spin-orbit coupling, simulate massless Dirac fermions in the strongly correlated regime with full SU(2) symmetry. By correlating Rydberg-exciton sensing with moiré exciton-polarons, we detect a Mott gap at the Dirac point persisting up to 110 K. We further identify correlated states at ν = - 1 with weak ferromagnetic coupling, and at fractional fillings. Our results highlight the potential for exploring quantum many-body phenomena in twisted two-dimensional materials.