门控定义双层石墨烯超晶格中谷霍尔模散射的尺寸与杂质效应
Size and Impurity Effects on Scattering of Valley Hall Modes in Gate-Defined Bilayer Graphene Superlattices
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中文总结 AI 辅助
本文通过紧束缚模拟研究门控定义双层石墨烯超晶格中谷霍尔模的散射，发现杂质共振隧穿可增强超晶格岛重叠，栅图案失对准不破坏拓扑保护，且可通过抑制散射实现岛的密集放置。
中文摘要 AI 辅助
本文对伯纳尔双层石墨烯（BLG）中的门控定义岛进行紧束缚模拟。岛边界上的能隙符号反转产生拓扑保护的谷霍尔模。我们聚焦于这类岛周围的谷霍尔模是否可作为量子行走的载体或模拟弱耦合系统，以及它们的隧穿如何受能隙内杂质影响的具体问题。此外，我们探讨了顶、底栅图案的失对准对岛间隧穿性质的影响。主要结果表明，通过杂质的共振隧穿会增强超晶格岛之间的重叠，而在宽参数范围内，失对准不会破坏拓扑保护。另外，我们研究了双岛几何结构，显示可利用被抑制的散射在单个样品上更密集地放置岛。
英文摘要
In the present paper we perform a tight-binding simulation of gate-defined islands in Bernal bilayer graphene (BLG). The inversion of the gap sign on the boundaries of the islands creates topologically-protected valley Hall modes. We focus on the specific questions of whether the valley Hall modes around such islands could serve as a host for quantum walks or simulate weakly coupled systems, and how their tunneling is affected by in-gap impurities. In addition, we discuss the effect of misalignment of top and bottom gate patterns on the tunneling properties between islands. Our main results show that resonant tunneling via an impurity enhances overlap between superlattice islands, while misalignment does not break topological protection over a wide parameter regime. In addition, we study the two-island geometry and show that it is possible to leverage suppressed scattering to place islands more densely on a single sample.
