Correlated states in doubly-aligned hBN/graphene/hBN heterostructures

Interfacial moire superlattices in van der Waals vertical assemblies effectively reconstruct the crystal symmetry, leading to opportunities for investigating exotic quantum states. Notably, a two-dimensional nanosheet has top and bottom open surfaces, allowing the specific case of doubly aligned super-moire lattice to serve as a toy model for studying the tunable lattice symmetry and the complexity of related electronic structures. Here, we show that by doubly aligning a graphene monolayer to both top and bottom encapsulating hexagonal boron nitride (h-BN), multiple conductivity minima are observed away from the main Dirac point, which are sensitively tunable with respect to the small twist angles. Moreover, our experimental evidences together with theoretical calculations suggest correlated insulating states at integer fillings of -5, -6, -7 electrons per moire unit cell, possibly due to inter-valley coherence. Our results provide a way to construct intriguing correlations in 2D electronic systems in the weak interaction regime. The alignment of three 2D nanosheets leads to the formation of super-moire atomic lattices, which can influence the electronic properties of van der Waals structures. Here, the authors report evidence of possible correlated insulating states in doubly-aligned hBN/graphene/hBN heterostructures, in a weak-interaction regime.

Automated summary

The formation of interfacial moire superlattices in van der Waals vertical assemblies reconstructs crystal symmetry and provides opportunities for investigating exotic quantum states. The alignment of graphene monolayer to both top and bottom encapsulating hexagonal boron nitride leads to observed conductivity minima and correlated insulating states in a weak-interaction regime. The alignment of three 2D nanosheets leads to the formation of super-moire atomic lattices, influencing the electronic properties of van der Waals structures.