Dipolar excitonic insulator in a moire lattice

Two-dimensional moire materials provide a highly controllable solid-state platform for studies of quantum phenomena(1-3). To date, experimental studies have focused on correlated electronic states, whereas correlated bosonic states in moire materials have received less attention. Here we report the observation of a correlated dipolar excitonic insulator-a charge-insulating state driven by exciton formation(4)-in a device where a WSe2 monolayer and WSe2/WS2 moire bilayer are coupled via Coulomb interactions. The system is a Mott insulator when all the holes reside in the moire layer. Under an out-of-plane electric field, the holes can be continuously transferred to the WSe2 monolayer, but remain strongly bound to the empty moire sites, effectively forming an interlayer exciton fluid in the moire lattice. We further observe the emergence of local magnetic moments in the WSe2 monolayer induced by the strong interlayer Coulomb correlation. Our result provides a platform for realizing correlated quantum phenomena described by bosonic lattice models in a solid-state system, complementary to cold-atom setups(5).

Automated summary

This study observes a correlated dipolar excitonic insulator and realizes a charge-insulating state driven by exciton formation in moire materials. Previous experimental studies have mainly focused on correlated electronic states. The results show that correlated quantum phenomena described by bosonic lattice models can be achieved in solid-state systems.