Quantum melting of generalized Wigner crystals

Recent experimental studies have established that moiré materials consisting of transition metal dichalcogenide bilayers host correlated insulating states at a series of fractional fillings of the moiré superlattice. In order to minimize the long-range Coulomb interaction electrons localize on a subset of moiré sites, giving rise to generalized Wigner crystals with charge orders that depend on the filling fraction. We combine exact diagonalization calculations in momentum space and a description in terms of extended t − J models to investigate the properties of the crystalline phases from the classical lattice gas limit up to the quantum melting regime, where quantum fluctuations start to dominate. We address the absence of particle-hole symmetry in the charge gaps relative to half-filling, and the nature of the states on the metallic side of these metal-insulator transitions.