Cheung Christopher T S, Goodwin Zachary A H, Han Yixuan, Lu Jiong, Mostofi Arash A, Lischner Johannes
Departments of Physics and Materials and the Thomas Young Center for Theory and Simulation of Materials, Imperial College London, South Kensington Campus, London SW7 2AZ, U.K.
John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, United States.
Nano Lett. 2024 Oct 2;24(39):12088-12094. doi: 10.1021/acs.nanolett.4c02750. Epub 2024 Sep 19.
Twisted bilayers of 2D materials have emerged as a tunable platform for studying broken symmetry phases. While most interest has been focused toward emergent states in systems whose constituent monolayers do not feature broken symmetry states, assembling monolayers that exhibit ordered states into twisted bilayers can also give rise to interesting phenomena. Here, we use first-principles density-functional theory calculations to study the atomic structure of twisted bilayer NbSe whose constituent monolayers feature a charge density wave. We find that different charge density wave states coexist in the ground state of the twisted bilayer: monolayer-like 3 × 3 triangular and hexagonal charge density waves are observed in low-energy stacking regions, while stripe charge density waves are found in the domain walls surrounding the low-energy stacking regions. These predictions, which can be tested by scanning tunneling microscopy experiments, highlight the potential to create complex charge density wave ground states in twisted bilayer systems.
二维材料的扭曲双层已成为研究破缺对称相的一个可调谐平台。虽然大多数研究兴趣集中在其组成单层不具有破缺对称态的系统中的新兴态，但将呈现有序态的单层组装成扭曲双层也能产生有趣的现象。在这里，我们使用第一性原理密度泛函理论计算来研究扭曲双层NbSe的原子结构，其组成单层具有电荷密度波。我们发现不同的电荷密度波态共存于扭曲双层的基态中：在低能堆叠区域观察到类似单层的3×3三角形和六边形电荷密度波，而在低能堆叠区域周围的畴壁中发现条纹电荷密度波。这些预测可通过扫描隧道显微镜实验进行验证，凸显了在扭曲双层系统中创造复杂电荷密度波基态的潜力。
