论文标题
来自H-BN底物内部扭曲界面的2D材料的通用超级超级潜力
Universal superlattice potential for 2D materials from twisted interface inside h-BN substrate
论文作者
论文摘要
2D材料中的横向超晶格正在成为探索新型量子现象的强大平台,可以通过与另一层形成Moiré图案的接近耦合来实现。然而,这种方法是侵入性的,特定于物质的,需要小晶格不匹配和合适的带对齐方式,在很大程度上限于石墨烯和过渡金属二甲硅烷基(TMDS)。抗平行(AA')堆叠顺序的六角硼(H-BN)一直是必不可少的构建块,因为介电基板和封盖层用于实现高质量的范德华设备。对Bernal(AB)堆叠的偏好对准H-BN也有新兴的兴趣,其中破裂的反转和镜面对称性导致平面外电化极化,并由层间翻译控制的符号。在这里,我们表明,可以利用H-BN基板或封盖层内几乎平行的界面处的横向图案电化极化,以在一般2D材料中产生非侵入性的通用超晶格电位。这种H-BN底物上的单层Mose2,Black Phosphorus和抗磁磁MNPSE3的第一个原理计算证明了可行性。潜在的强度可以达到200 MeV,可以通过选择与H-BN界面的目标材料的垂直距离在此范围内自定义。我们还发现H-BN表面的平面外电场相当大,这可以实现TMD双层中层间激子和偶性分子的超晶格潜力。该想法进一步概括为AB堆叠的H-BN膜,其呈扭转,相邻层均以一个角度扭曲,从而使电势和场强以膜厚度缩放,并饱和至具有手性结构的准周期。
Lateral superlattices in 2D materials are emerging as a powerful platform for exploring novel 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 anti-parallel (AA') stacking order 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 with sign controlled by interlayer translation. Here we show that the laterally patterned electrical polarization at a nearly parallel interface within the h-BN substrate or capping layer can be exploited to create non-invasively 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 substrate. The potential strength can reach 200 meV, customizable in this range through choice of vertical 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 film 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.