Researchers have created a honeycomb moiré superlattice using twisted MoSe2 homobilayers to observe correlated insulating states in slow Dirac fermions, according to a study published in Nature Communications on August 14, 2026.
The experiment addresses a long-standing challenge in condensed matter physics. Strong Coulomb repulsion is predicted to open a many-body charge gap at graphene's Dirac point, turning the semimetal into a Mott insulator. In pristine graphene, however, a large Fermi velocity dominates electronic interactions and keeps this correlated phase elusive.
To bypass that limitation, the team engineered a graphene-like band structure inside twisted MoSe2 homobilayers where the Fermi velocity dropped by nearly two orders of magnitude. These slow moiré bands fold from the valence band maximum at the Γ valley with negligible spin-orbit coupling. This structure simulates massless Dirac fermions in a strongly correlated regime with full SU(2) symmetry.
Using Rydberg-exciton sensing correlated with moiré exciton-polarons, the scientists detected a Mott gap at the Dirac point that remained stable up to 110 Kelvin. Measurements also revealed correlated states at filling factor ν = −1 showing weak ferromagnetic coupling, along with further states at fractional fillings.
Co-lead authors Dongyang Yang, Jing Liang, and Haodong Hu carried out the work with colleagues across the University of British Columbia, Tamkang University, the University of Southern California, and Japan's National Institute for Materials Science. Computational analysis used supercomputing time awarded by the U.S. Department of Energy INCITE program at the Argonne and Oak Ridge Leadership Computing Facilities.
