An atomistic approach for the structural and electronic properties of twisted bilayer graphene-boron nitride heterostructures

Twisted bilayer graphene (TBG) has taken the spotlight in the condensed matter community since the discovery of correlated phases. In this work, we study heterostructures of TBG and hexagonal boron nitride (hBN) using an atomistic tight-binding model together with semi-classical molecular dynamics to consider relaxation effects. The hBN substrate has significant effects on the band structure of TBG even in the case where TBG and hBN are not aligned. Specifically, the substrate induces a large mass gap and strong pseudo-magnetic fields that break the layer degeneracy. Interestingly, such degeneracy can be recovered with a second hBN layer. Finally, we develop a continuum model that describes the tight-binding band structure. Our results show that a real-space tight-binding model in combination with semi-classical molecular dynamics is a powerful tool to study the electronic properties of moire heterostructures, and to explain experimental results in which the effect of the substrate plays an important role.

Automated summary

This study investigates the heterostructures of twisted bilayer graphene (TBG) and hexagonal boron nitride (hBN) using an atomistic tight-binding model and semi-classical molecular dynamics. The hBN substrate significantly affects the band structure of TBG, inducing mass gaps and pseudo-magnetic fields that break layer degeneracy. However, the degeneracy can be recovered with a second hBN layer. Real-space tight-binding model combined with semi-classical molecular dynamics is shown to be a powerful tool for studying electronic properties of moire heterostructures.