Commensurate and incommensurate double moire interference in graphene encapsulated by hexagonal boron nitride

TL;DR

This paper investigates how interference between double moire patterns in graphene encapsulated by hexagonal boron nitride affects electronic properties, revealing constructive and destructive interference effects and their impact on the density of states.

Contribution

It demonstrates the influence of relative stacking and twist angles on moire interference effects and electronic structure in graphene/BN heterostructures, including the emergence of pseudogaps and van Hove singularities.

Findings

Constructive interference leads to large pseudogaps (~0.5 eV).

Destructive interference can partially restore electron-hole symmetry.

Double moire features cause van Hove singularities with potential for strong correlations.

Abstract

Interference of double moire patterns of graphene (G) encapsulated by hexagonal boron nitride (BN) can alter the electronic structure features near the primary/secondary Dirac points and the electron-hole symmetry introduced by a single G/BN moire pattern depending on the relative stacking arrangements of the top/bottom BN layers. We show that strong interference effects are found in nearly aligned BN/G/BN and BN/G/NB and obtain the evolution of the associated density of states as a function of moire superlattice twist angles. For equal moire periods and commensurate patterns with $\Delta \phi = 0^{\circ}$ modulo $60^{\circ}$ angle differences the patterns can add up constructively leading to large pseudogaps of about $\sim 0.5$ eV on the hole side or cancel out destructively depending on their relative sliding, e.g. partially recovering electron-hole symmetry. The electronic structure of moire quasicrystals for $\Delta \phi =30^{\circ}$ differences reveal double moire features in the density of states with almost isolated van Hove singularities where we can expect strong correlations.