Uncovering Topological Edge States in Twisted Bilayer Graphene
Uncovering Topological Edge States in Twisted Bilayer Graphene
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揭示扭曲双层石墨烯中的拓扑边缘态
DOI：
10.1021/acs.nanolett.2c01481
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发表时间：
2022
期刊：
影响因子：
10.8
通讯作者：
Xia, Fengnian
中科院分区：
文献类型：
--
作者：
Fortin-Deschênes, Matthieu;Pu, Rui;Zhou, Yan-Feng;Ma, Chao;Cheung, Patrick;Watanabe, Kenji;Taniguchi, Takashi;Zhang, Fan;Du, Xu;Xia, Fengnian
扭曲双层石墨烯（t-BLG）最近被引入作为一个丰富的物理平台，显示平坦的电子带，强关联态，和非常规的超导性。研究已经暗示了t-BLG的莫尔狄拉克带的一种不寻常的Z2拓扑。然而，这种莫尔带拓扑结构和相关的边缘状态的直接实验证据仍然缺乏。在这里，我们使用超导量子干涉术，重建的空间超导电流分布在t-BLG约瑟夫森结，并揭示了位于超晶格带隙中的边缘态的存在。边缘导电的情况下，在高电阻区域外的超晶格带隙证实，边缘输运起源于填充的电子状态位于带隙内，并进一步允许我们排除其他几个边缘导电机制。这些结果证实了扭曲双层石墨烯的不寻常的莫尔带拓扑结构，并将激发进一步的研究来探索其后果。
Twisted bilayer graphene (t-BLG) has recently been introduced as a rich physical platform displaying flat electronic bands, strongly correlated states, and unconventional superconductivity. Studies have hinted at an unusualZ2topology of the moiré Dirac bands of t-BLG. However, direct experimental evidence of this moiré band topology and associated edge states is still lacking. Herein, using superconducting quantum interferometry, we reconstructed the spatial supercurrent distribution in t-BLG Josephson junctions and revealed the presence of edge states located in the superlattice band gaps. The absence of edge conduction in high resistance regions just outside the superlattice band gap confirms that the edge transport originates from the filling of electronic states located inside the band gap and further allows us to exclude several other edge conduction mechanisms. These results confirm the unusual moiré band topology of twisted bilayer graphene and will stimulate further research to explore its consequences.