Topological Wigner Molecule Crystal in Transition-Metal Dichalcogenide Moiré Superlattices

As a versatile platform for exploring exotic quantum phases, moiré superlattices, ranging from twisted graphene to twisted transition metal dichalcogenides, have been intensively studied. In this work, based on exact diagonalization and Hartree-Fock mean-field calculations, the interaction-driven topological phases are investigated in hole-doped twisted bilayer MoS₂ at the high filling factor ν = 3. Besides the nematic insulator and quantum anomalous Hall phases, the topological Wigner molecule crystal (TWMC) phase is found in the phase diagram. The emergence of TWMC is characterized by the enhanced dimer bonding between trimer molecules trapped in the honeycomb moiré potential, resulting in the hole charge density splitting from one to three peaks in each trimer molecule. The nontrivial topology of TWMC is identified by the nonzero Z₂ Berry phase and fractionally filled topological corner states. Combining topological and Wigner physics, our results demonstrate the formation of TWMC in moiré superlattices, which can be detected by state-of-the-art scanning tunneling microscopy measurements.