Emergence of Topologically Protected Helical States in Minimally Twisted Bilayer Graphene.
Emergence of Topologically Protected Helical States in Minimally Twisted Bilayer Graphene.
复制标题
最小扭曲双层石墨烯中拓扑保护螺旋态的出现。
DOI：
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发表时间：
2018
期刊：
影响因子：
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通讯作者：
B. LeRoy
中科院分区：
文献类型：
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作者：
Shengqiang Huang;Kyounghwa Kim;D. K. Efimkin;T. Lovorn;T. Taniguchi;Kenji Watanabe;A. Macdonald;E. Tutuc;B. LeRoy
在反转对称性被破坏的双层石墨烯样品中，量子谷霍尔基态支持沿AB和BA堆积区之间的域壁局域化的对射拓扑保护螺旋(TPH)边态。此外，当层与层之间施加一个小的扭角时，在双层石墨烯中形成了由AB和BA堆积区组成的莫尔图案。我们制备了波长大于50 nm的设计莫尔晶体，并通过扫描隧道谱测量证明了TPH态在畴壁网络上的出现。我们观察到只有当AB区和BA区间隙时，域壁上TPH态的双线轮廓。我们的结果表明，一种实用而灵活的方法来构建TPH态网络。
Bilayer graphene samples in which inversion symmetry is broken have quantum valley Hall ground states that support counterpropogating topologically protected helical (TPH) edge states localized along domain walls between AB and BA stacking regions. Moreover, a moir\'e pattern consisting of AB and BA stacking regions separated by a grid of domain walls, forms in bilayer graphene when a small twist-angle is applied between the layers. We fabricate designer moir\'e crystals with wavelengths longer than 50 nm and demonstrate the emergence of TPH states on the domain wall network by scanning tunneling spectroscopy measurements. We observe a double-line profile of the TPH states on the domain walls, only occurring when the AB and BA regions are gapped. Our results demonstrate a practical and flexible method for TPH state network construction.