云纹
双层石墨烯
材料科学
扫描隧道显微镜
凝聚态物理
光学
量子隧道
魔法角
石墨烯
物理
分子物理学
谱线
纳米技术
量子力学
作者
Long-Jing Yin,Ling-Hui Tong,Yue-Ying Zhou,Yang Zhang,Yuan Tian,Li Zhang,Lijie Zhang,Zhihui Qin
出处
期刊:Physical review
日期:2022-05-19
卷期号:105 (20)
被引量:3
标识
DOI:10.1103/physrevb.105.l201405
摘要
Low-energy moir\'e flat bands in magic-angle twisted bilayer graphene (tBG) have demonstrated incredible potentials to exhibit rich exotic quantum phenomena. Theoretically, the moir\'e flat bands of tBG are based on the extended structures, i.e., the moir\'e patterns with periodic boundary conditions. However, a fundamental question of whether the flat bands can exist in the graphene moir\'e patterns with a reduced structure symmetry, such as sample edges, remains unanswered. Here, via scanning tunneling microscopy and spectroscopy, we study the local electronic properties of a magic-angle tBG near the sample terminated edge and report a direct observation of breakdown of the moir\'e flat bands. We show that the moir\'e electronic structures, including the low-energy flat bands, can sufficiently exist in a complete moir\'e spot, i.e., a moir\'e supercell, right at the edge even the translational symmetry of the moir\'e patterns is broken in one direction. However, the flat-band characteristic is obviously absent in the incomplete moir\'e spots that are partly terminated by the edge. Our results indicate that a whole moir\'e spot is sufficient and indispensable for the generation of the effective moir\'e flat bands in tBG.
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