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

• Published in: NPJ 2D materials and applications Vol. 5; no. 1; pp. 1 - 7
• Main Authors: Zhao, Pei, Xiao, Chengxin, Yao, Wang
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 12.04.2021; Nature Publishing Group; Nature Portfolio
• Subjects: 639/301/119/995; 639/766/25; Antiferromagnetism; Bilayers; Boron nitride; Chemistry and Materials Science; Coupling (molecular); Electric fields; Excitons; Field strength; Film thickness; First principles; Graphene; Interlayers; Materials Science; Nanotechnology; Polarization; Quantum phenomena; Stacking; Substrates; Superlattices; Surfaces and Interfaces; Thin Films; Transition metal compounds; Two dimensional materials
• ISSN: 2397-7132; 2397-7132
• DOI: 10.1038/s41699-021-00221-4

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 MoSe 2 , black phosphorus, and antiferromagnetic MnPSe 3 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.