Synergistic correlated electronic states in coupled graphene-insulator heterostructures

In this work, we study the synergistic correlated electronic states in two distinct types of interacting electronic systems coupled by interlayer Coulomb interactions. We propose that such a scenario can be realized in a new type of Coulomb coupled graphene-insulator heterostructures with gate tunable band alignment. We find that, by virtue of the interlayer Coulomb coupling between the interacting electrons in the two layers, intriguing correlated physics that is not seen in either of the individual layer would emerge in a cooperative and synergistic manner. Specifically, as a result of the band alignment, charge carriers can be transferred between graphene and the substrate under the control of gate voltages, which may yield a long-wavelength electronic crystal at the surface of the substrate. The electronic crystal in turn exerts a superlattice Coulomb potential to the Dirac electrons in graphene, which reduces the non-interacting Fermi velocity such that $e$-$e$ Coulomb interactions within graphene would give rise to a gapped Dirac state at the charge neutrality point, concomitant with interaction-enhanced Fermi velocity. Reciprocally, the electronic crystal formed in the substrate can be substantially stabilized in such coupled bilayer heterostructure by virtue of the cooperative interlayer Coulomb coupling. We have further performed high-throughput first principles calculations, and found a number of promising insulating materials as candidate substrates for graphene to demonstrate such effects.