论文标题
内在的非线性厅效应和闸门可切口的浆果曲率在扭曲的双层石墨烯中滑动
Intrinsic nonlinear Hall effect and gate-switchable Berry curvature sliding in twisted bilayer graphene
论文作者
论文摘要
尽管观察量子异常的霍尔效应和非局部传输响应揭示了由扭曲的双层石墨烯中浆果曲率控制的非平凡带拓扑结构，但最近的一些作品报告了石墨烯超级晶格中的非线性霍尔信号，这些信号是由外部障碍散射引起的，而不是固有的berry berry berry curvature curvature Dipole矩。在这项工作中，我们报告了高质量扭曲的双层石墨烯设备中的浆果曲率偶极子诱导的固有非线性霍尔效应。我们还发现，由于浆果曲率热点的场诱导滑动，位移场的应用实质上改变了非线性霍尔电压的方向和振幅。我们的工作不仅证明了浆果曲率偶极子在具有低疾病密度的石墨烯超级晶格中产生内在的非线性霍尔信号，而且还证明了扭曲的双层石墨烯是第二个谐波生成和整流的敏感和微调平台。
Though the observation of the quantum anomalous Hall effect and nonlocal transport response reveals nontrivial band topology governed by the Berry curvature in twisted bilayer graphene, some recent works reported nonlinear Hall signals in graphene superlattices that are caused by the extrinsic disorder scattering rather than the intrinsic Berry curvature dipole moment. In this work, we report a Berry curvature dipole induced intrinsic nonlinear Hall effect in high-quality twisted bilayer graphene devices. We also find that the application of the displacement field substantially changes the direction and amplitude of the nonlinear Hall voltages, as a result of a field-induced sliding of the Berry curvature hotspots. Our work not only proves that the Berry curvature dipole could play a dominant role in generating the intrinsic nonlinear Hall signal in graphene superlattices with low disorder densities, but also demonstrates twisted bilayer graphene to be a sensitive and fine-tunable platform for second harmonic generation and rectification.
