Universal superlattice potential for 2D materials from twisted interface inside h-BN substrate

Abstract

Lateral superlattices in 2D materials provide a powerful platform for exploring intriguing quantum phenomena, which can be realized through the proximity coupling in forming moiré pattern with another layer. This approach, however, is invasive, material-specific, and requires small lattice mismatch and suitable band alignment, largely limited to graphene and transition metal dichalcogenides (TMDs). Hexagonal boron nitride (h-BN) of antiparallel (AA′) stacking has been an indispensable building block, as dielectric substrates and capping layers for realizing high-quality van der Waals devices. There is also emerging interest on parallelly aligned h-BN of Bernal (AB) stacking, where the broken inversion and mirror symmetries lead to out-of-plane electrical polarization. Here we show the that laterally patterned electrical polarization at a nearly parallel interface within the h-BN substrate can be exploited to create noninvasively a universal superlattice potential in general 2D materials. The feasibility is demonstrated by first principle calculations for monolayer MoSe2, black phosphorus, and antiferromagnetic MnPSe3 on such h-BN. The potential strength can reach 200 meV, customizable in this range through choice of distance of target material from the interface in h-BN. We also find sizable out-of-plane electric field at the h-BN surface, which can realize superlattice potential for interlayer excitons in TMD bilayers as well as dipolar molecules. The idea is further generalized to AB-stacked h-BN subject to torsion with adjacent layers all twisted with an angle, which allows the potential and field strength to be scaled up with film thickness, saturating to a quasi-periodic one with chiral structure.