Coupled Ferroelectricity and Correlated States in a Twisted Quadrilayer MoS₂ Moiré Superlattice

Moiré superlattices have emerged as a highly controllable quantum platform for exploration of various fascinating phenomena, such as Mott insulator states, ferroelectric order, unconventional superconductivity and orbital ferromagnetism. Although remarkable progress has been achieved, current research in moiré physics has mainly focused on the single species properties, while the coupling between distinct moiré quantum phenomena remains elusive. Here we demonstrate, for the first time, the strong coupling between ferroelectricity and correlated states in a twisted quadrilayer MoS₂ moiré superlattice, where the twist angles are controlled in sequence to be ∼ 57°, ∼ 0°, and ∼ –57°. Correlated insulator states are unambiguously established at moiré band filling factors v = 1, 2, 3 of twisted quadrilayer MoS₂. Remarkably, ferroelectric order can occur at correlated insulator states and disappears quickly as the moiré band filling deviates from the integer fillings, providing smoking gun evidences of the coupling between ferroelectricity and correlated states. Our results demonstrate the coupling between different moiré quantum properties and will hold great promise for new moiré physics and applications.