Atomic and electronic reconstruction at the van der Waals interface in twisted bilayer graphene
Atomic and electronic reconstruction at the van der Waals interface in twisted bilayer graphene
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DOI：
10.1038/s41563-019-0346-z
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发表时间：
2019-05-01
期刊：
影响因子：
41.2
通讯作者：
Kim, Philip
中科院分区：
文献类型：
--
作者：
Yoo, Hyobin;Engelke, Rebecca;Kim, Philip
控制二维货车德瓦尔斯（vdW）异质结构中的层间扭转角使得能够设计可调长度尺度（1-8）的准周期莫尔超晶格。在扭曲的双层石墨烯中，简单的莫尔超晶格能带描述表明，电子带宽可以被调整为与“魔角”处的vdW层间相互作用相当（9），表现出强烈的相关行为。然而，vdW层间相互作用也可以通过有利于层间可结晶性而在界面处引起显著的结构重构，这与层内晶格畸变竞争（10-16）。在这里，我们报告原子尺度的重建扭曲双层石墨烯及其对电子结构的影响。我们发现一个渐进的过渡，从一个不相称的莫尔结构的公度域与孤子边界的阵列，因为我们减少了跨特征交叉角，θ（c）近似为1度的扭曲角。在孤子状态（θ <θ（c）），原子和电子的重构变得重要，一个简单的莫尔带描述打破和二次狄拉克带出现。在施加横向电场，我们观察到电子传输沿着网络的一维拓扑通道，周围的交替三角形缺口域。原子和电子重建的vdW接口提供了一个新的途径，工程系统的连续可调性。
Control of the interlayer twist angle in two-dimensional van der Waals (vdW) heterostructures enables one to engineer a quasiperiodic moire superlattice of tunable length scale(1-8). In twisted bilayer graphene, the simple moire super-lattice band description suggests that the electronic band-width can be tuned to be comparable to the vdW interlayer interaction at a 'magic angle'(9), exhibiting strongly correlated behaviour. However, the vdW interlayer interaction can also cause significant structural reconstruction at the interface by favouring interlayer commensurability, which competes with the intralayer lattice distortion(10-16). Here we report atomic-scale reconstruction in twisted bilayer graphene and its effect on the electronic structure. We find a gradual transition from an incommensurate moire structure to an array of commensurate domains with soliton boundaries as we decrease the twist angle across the characteristic crossover angle, theta(c) approximate to 1 degrees. In the solitonic regime (theta < theta(c)) where the atomic and electronic reconstruction become significant, a simple moire band description breaks down and the secondary Dirac bands appear. On applying a transverse electric field, we observe electronic transport along the network of one-dimensional topological channels that surround the alternating triangular gapped domains. Atomic and electronic reconstruction at the vdW interface provide a new pathway to engineer the system with continuous tunability.