Gate-controlled localization to delocalization transition of flat band wavefunction in twisted monolayer–bilayer graphene

作     者：李思宇 王政文 薛禹承 曹路 Kenji Watanabe Takashi Taniguchi 高鸿钧 毛金海 Siyu Li;Zhengwen Wang;Yucheng Xue;Lu Cao;Kenji Watanabe;Takashi Taniguchi;Hongjun Gao;Jinhai Mao

作者机构：Institute of PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Sciences and CAS Center for Excellence in Topological Quantum ComputationUniversity of Chinese Academy of SciencesBeijing 100049China College of Materials Science and Optoelectronic TechnologyCenter of Materials Science and Optoelectronics EngineeringUniversity of Chinese Academy of SciencesBeijing 100049China Advanced Materials LaboratoryNational Institute for Materials ScienceTsukuba 305-0044Japan 

出 版 物：《Chinese Physics B》 (中国物理B（英文版）)

年 卷 期：2023年第32卷第6期

页      面：102-105页

核心收录：

学科分类：081702[工学-化学工艺] 07[理学] 070205[理学-凝聚态物理] 08[工学] 0817[工学-化学工程与技术] 0702[理学-物理学] 

基　　金：support from the National Key R&D Program of China (Grant No. 2019YFA0307800) Beijing Natural Science Foundation (Grant No. Z190011) the National Natural Science Foundation of China (Grant No. 11974347) Fundamental Research Funds for the Central Universities 

主　　题：graphene Van der Waals heterostructures scanning tunneling microscopy/spectroscopy 

摘      要：Twisted graphene systems with flat bands have attracted much attention for they are excellent platforms to research novel quantum phases. Recently, transport measurements about twisted monolayer–bilayer graphene(t MBG) have shown the existence of correlated states and topological states in this system. However, the direct observations of the band structures and the corresponding spatial distributions are still not sufficient. Here we show that the distributions of flat bands in t MBG host two different modes by scanning tunneling microscopy and spectroscopy(STM/S). By tuning our t MBG device from the empty filling state to the full filling state through the back gate, we observe that the distributions of two flat bands develop from localized mode to delocalized mode. This gate-controlled flat band wavefunction polarization is unique to the t MBG system. Our work suggests that t MBG is promising to simulate both twisted bilayer graphene(TBG) and twisted double bilayer graphene(t DBG) and would be an ideal platform to explore novel moiré physics.