Arise of the gapless quantum spin liquid in moiré transition metal dichalcogenide due to ring exchange interaction

We study the ground-state properties of twisted transition metal dichalcogenide (TMD) hetero-bilayers using density matrix renormalization group (DMRG) simulations of an effective spin model with four-spin ring exchange interactions. Our results demonstrate a gapless quantum spin liquid (QSL) phase, stabilized by the ring exchange term, and a competing valence bond solid (VBS) phase. The QSL exhibits power-law spin correlations and a central charge consistent with multiple gapless modes. Tuning the dielectric constant drives a continuous transition between these phases. Our results emphasize the role of ring exchange interactions in moiré TMDs and demonstrate their potential as quantum simulators.