Higher order gaps in the renormalized band structure of doubly aligned hBN/bilayer graphene moiré superlattice

Abstract

This paper presents our findings on the recursive band gap engineering of chiral fermions in bilayer graphene doubly aligned with hBN. Using two interfering moiré potentials, we generate a supermoiré pattern that renormalizes the electronic bands of the pristine bilayer graphene, resulting in higher order fractal gaps even at very low energies. These Bragg gaps can be mapped using a unique linear combination of periodic areas within the system. To validate our findings, we use electronic transport measurements to identify the position of these gaps as a function of the carrier density. We establish their agreement with the predicted carrier densities and corresponding quantum numbers obtained using the continuum model. Our study provides strong evidence of the quantization of the momentum-space area of quasi-Brillouin zones in a minimally incommensurate lattice. It fills important gaps in the understanding of band structure engineering of Dirac fermions with a doubly periodic superlattice spinor potential.

Moiré superlattices arising from growth induced by screw dislocations in layered materials

“…[1][2][3][4][5][6] In addition to a variety of materials and the dependence of layer thickness, stacking 2D layers into artificial van der Waals heterostructures also provides degrees of freedom to engineer their electronic and optical properties. [7,8] The resulting modulated strain field and electrostatic potential combined with the ubiquitous interlayer coupling may give rise to distinct emergent physical properties, [23][24][25][26] for example, the Hofstadter butterfly spectra, [17,[27][28][29] cloned Dirac Fermions, [17][18][19] fractional quantum Hall effects [28][29][30] and topological mosaics [31] in graphene-based and transition metal dichalcogenides-based Moiré superlattices (MSLs). Thus far, researchers have realized the MSLs fabrication by wet transfer of mechanically exfoliated monolayers, [32][33][34][35] epitaxial growth, [36][37][38] one-pot solvothermal approaches, [39] and so forth.…”