Abstract
While the ground state phase diagram of the correlated flat-band systems have been intensively investigated, the dynamic and thermodynamic properties of such lattice models are less explored, but it is the latter which is most relevent to the experimental probes of the quantum Moiré materials such as twisted bilayer graphene and transition metal dichalcogenides. Here we show, by means of momentum-space quantum Monte Carlo and exact diagonalization, there exists an universal thermodynamic characteristic for the correlated flat-band models at integer band fillings. The finite temperature transition from the interaction-driven quantum anomalous Hall insulator ground state to the metallic state, always happens at a much lower temperature compared with the single-particle gap generated by the long-range Coulomb interaction. We find such low transition temperature comes from the proliferation of excitonic particle-hole collective excitations, which “quantum teleport” the electrons across the gap between different topological bands to restore the broken time-reversal symmetry and give rise to enhanced charge compressibilities.
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