Super-moire lattices and flat bands in hBN encapsulated graphene

Although the encapsulation of graphene between hBN layers has been routinely used to improve the electric properties of graphene, it is only recently that an almost perfect alignment with both top and bottom hBN layers has been realized [1-3]. This has paved the way to combining the effect of the moire patterns induced by each hBN layer and thus generating a longer-range composite super-moire structure. With experimental precision of ~0.1 degrees, this allows for the modification of the low energy electronic properties in the graphene layer by generating new mini-bands and Dirac points. Furthermore, we have shown that relaxation effects provide a further enhancement of the these effects, generating band-gaps at the principal and secondary Dirac points [4]. We show that under certain conditions flat mini-bands can develop, making this system amenable to the appearance of strong correlations. Finally, we explore additional effects and degrees of freedom by considering instead an encapsulated bilayer graphene.

[1] N. R. Finney, et al. , Nat. Nanotechnol. 14, 11 (2019), 1029–1034
[3] Z. Wang, et al., Sci. Adv. 5, 12, (2019), eaay8897
[4] M. Andelkovic, et. al, Nano Lett. 20, 2, (2020) 979-988