Emergence of Tertiary Dirac Points in Graphene Moire Superlattices
Emergence of Tertiary Dirac Points in Graphene Moire Superlattices
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DOI：
10.1021/acs.nanolett.7b00735
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发表时间：
2017-06-01
期刊：
影响因子：
10.8
通讯作者：
Zhane, Yuanbo
中科院分区：
文献类型：
--
作者：
Chen, Guorui;Sui, Mengqiao;Zhane, Yuanbo
晶体固体的电子结构很大程度上取决于其晶格结构。范德华固体（具有二维 (2D) 原子膜受控堆叠的人造晶体）的最新进展使得能够创建具有新颖电子结构的材料。特别是，将石墨烯堆叠在六方氮化硼（hBN）上会引入莫尔超晶格，从根本上改变石墨烯能带结构并产生二次狄拉克点（SDP）。在这里，我们发现六方氮化硼上石墨烯中莫尔超晶格的形成产生了新的、意想不到的结果：出现了一组三级狄拉克点（TDP），当样品受到外部磁场作用时，这会产生额外的朗道能级组。我们的观察暗示在适当的载流子掺杂和磁场下，在莫尔超晶格顶部形成了隐藏的凯库勒超结构。
The electronic structure of a crystalline solid is largely determined by its lattice structure. Recent advances in van der Waals solids, artificial crystals with controlled stacking of two-dimensional (2D) atomic films, have enabled the creation of materials with novel electronic structures. In particular, stacking graphene on hexagonal boron nitride (hBN) introduces a moire superlattice that fundamentally modifies graphenes band structure and gives rise to secondary Dirac points (SDPs). Here we find that the formation of a moire superlattice in graphene on hBN yields new, unexpected consequences: a set of tertiary Dirac points (TDPs) emerge, which give rise to additional sets of Landau levels when the sample is subjected to an external magnetic field. Our observations hint at the formation of a hidden Kekule superstructure on top of the moire superlattice under appropriate carrier doping and magnetic fields.