Department of Physics and Astronomy, University of Manchester, Manchester, UK.
National Graphene Institute, University of Manchester, Manchester, UK.
Nature. 2023 Aug;620(7975):756-761. doi: 10.1038/s41586-023-06264-5. Epub 2023 Jul 19.
Van der Waals assembly enables the design of electronic states in two-dimensional (2D) materials, often by superimposing a long-wavelength periodic potential on a crystal lattice using moiré superlattices. This twistronics approach has resulted in numerous previously undescribed physics, including strong correlations and superconductivity in twisted bilayer graphene, resonant excitons, charge ordering and Wigner crystallization in transition-metal chalcogenide moiré structures and Hofstadter's butterfly spectra and Brown-Zak quantum oscillations in graphene superlattices. Moreover, twistronics has been used to modify near-surface states at the interface between van der Waals crystals. Here we show that electronic states in three-dimensional (3D) crystals such as graphite can be tuned by a superlattice potential occurring at the interface with another crystal-namely, crystallographically aligned hexagonal boron nitride. This alignment results in several Lifshitz transitions and Brown-Zak oscillations arising from near-surface states, whereas, in high magnetic fields, fractal states of Hofstadter's butterfly draw deep into the bulk of graphite. Our work shows a way in which 3D spectra can be controlled using the approach of 2D twistronics.
范德华组装使二维（2D）材料中电子态的设计成为可能，通常是通过在晶格上使用莫尔超晶格叠加长波长周期性势。这种扭曲电子学方法已经产生了许多以前未描述的物理现象，包括扭曲双层石墨烯中的强关联和超导、共振激子、过渡金属硫属化物莫尔结构中的电荷有序和魏格纳结晶以及在石墨烯超晶格中的霍夫施塔特蝴蝶谱和布朗-扎克量子振荡。此外，扭曲电子学已被用于修饰范德华晶体界面处的近表面态。在这里，我们表明，与另一个晶体——即晶面排列的六方氮化硼——的界面处的超晶格势可以调谐三维（3D）晶体（如石墨）中的电子态。这种排列导致了几个来自近表面态的李希特跃迁和布朗-扎克振荡，而在高磁场中，霍夫施塔特蝴蝶的分形态则深入到石墨的体相中。我们的工作表明，通过 2D 扭曲电子学的方法可以控制 3D 谱。
