Wang Zhen-Yu, Ma Jia-Jun, Chen Qianqian, Wu Kefan, Xu Shuigang, Dai Qing, Zhu Zheng, Ren Jindong, Gao Hong-Jun, Lin Xiao
Institute of Physics and University of Chinese Academy of Sciences, Chinese Academy of Sciences, Beijing 100190, China.
Kavli Institute for Theoretical Sciences, University of Chinese Academy of Sciences, Beijing 100190, China.
Nanoscale. 2024 Oct 17;16(40):18852-18858. doi: 10.1039/d4nr02933j.
Direct visualization of the states originating from electron-electron interactions is of great importance for engineering the surface and interfacial properties of graphene-based quantum materials. For instance, the rotational symmetry breaking or nematic phase inferred from spectroscopic imaging has confirmed the existence of correlated states in a wide range of moiré materials. Here, we study the atomic-scale spatial distributions and symmetry of wave functions in gate-tunable twisted double bilayer graphene by employing scanning tunneling microscopy/spectroscopy and continuum model calculations. A series of spectroscopic imaging analyses are used to identify dominant symmetry breaking of the emergent states. Interestingly, in non-integer hole fillings, a completely new localized electronic state with rotational symmetry breaking is observed on the left side of the valence flat band. The degree of anisotropy is found to increase from the conduction flat band through the valence flat band to the new state. Our results provide an essential microscopic insight into the flat band and its adjacent state for a full understanding of their electric field response in twisted graphene systems.
直接可视化源自电子-电子相互作用的态对于调控基于石墨烯的量子材料的表面和界面性质至关重要。例如，从光谱成像推断出的旋转对称性破缺或向列相已证实了广泛的莫尔材料中存在关联态。在此，我们通过采用扫描隧道显微镜/光谱学和连续介质模型计算，研究了栅极可调谐扭曲双双层石墨烯中波函数的原子尺度空间分布和对称性。一系列光谱成像分析用于识别出射态的主要对称性破缺。有趣的是，在非整数空穴填充时，在价带平带左侧观察到一种具有旋转对称性破缺的全新局域电子态。发现各向异性程度从导带平带经价带平带向新态逐渐增加。我们的结果为深入了解平带及其相邻态提供了重要的微观见解，有助于全面理解它们在扭曲石墨烯系统中的电场响应。
