人工量子霍尔绝缘体中螺旋边的希尔伯特空间选择性开关
Hilbert-space selected switch of helical edges in an artificial quantum Hall insulator
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中文总结 AI 辅助
本研究通过CrOCl与扭转双层石墨烯间的界面电荷转移，实现了人工量子霍尔绝缘体中螺旋边缘通道的希尔伯特空间选择性开关，为波函数选择性控制边缘模式提供了新途径。
中文摘要 AI 辅助
量子霍尔效应承载一维拓扑保护的边缘通道，可作为奇异量子电子系统中的关键组成部分。然而，通过静电约束或对称性破缺来人工重构朗道能级拓扑，在实验上仍具挑战性。在此，我们展示了CrOCl与大角度扭转双层石墨烯之间的界面电荷转移，使原本解耦的每层石墨烯中的狄拉克朗道能级阶梯发生偏移，从而产生一系列新的复合填充构型。在电荷中性点，复合的$(+2,-2)$态仅涉及第零朗道能级，并变为完全绝缘，纵向电阻达到GΩ量级。相比之下，更高的复合零填充量子霍尔态，包括$(+6,-6)$和$(+10,-10)$，保留反向传播的螺旋边缘通道，并表现出显著的非局域输运，达到局域响应的50%。我们将这种开关行为归因于朗道旋量希尔伯特空间——当填充从$(+6,-6)$减少到$(+2,-2)$时，正交的$N=\pm1$轨道分量被移除，消除了与边缘兼容的通道，并使体态和边界输运均产生能隙。我们还在实验和理论上进一步检验了所观察到的有间隙态（gapped states）的相互作用本质。我们的结果表明，电荷转移为构造人工量子霍尔绝缘体提供了直接途径，为螺旋边缘模式的波函数选择性控制开辟了可能性。
英文摘要
Quantum Hall effects (QHE) host one-dimensional topologically-protected edge channels, which can serve as an essential ingredient in exotic quantum electronic systems. Yet the manual reconstruction of Landau-level topology, by electrostatic confinement or symmetry breaking, remains experimentally challenging. Here, we show that interfacial charge transfer in between CrOCl and large-angle twisted bilayer graphene offsets the two otherwise decoupled Dirac Landau-level ladders in each graphene layer, creating a new sequence of composite filling configurations. At charge neutrality, the composited $(+2,-2)$ state involves only the zeroth Landau levels and becomes fully insulating, with longitudinal resistance reaching the G$Ω$ regime. By contrast, higher composite zero-filling quantum Hall states, including $(+6,-6)$ and $(+10,-10)$, retain counter-propagating helical edge channels and exhibit pronounced non-local transport, reaching up to $50\%$ of the local response. We attribute such switching-behavior to the Landau-spinor Hilbert space -- as the filling is reduced from $(+6,-6)$ to $(+2,-2)$, the orthogonal $N=\pm1$ orbital components are removed, eliminating the edge-compatible channel and gapping both bulk and boundary transport. The interaction nature of the observed gapped sates was further examined both experimentally and theoretically. Our results suggest that charge transfer provides a direct route to engineer artificial quantum Hall insulators, opening possibilities for wavefunction-selective control of helical edge modes.
发表机构
- Shanxi University（山西大学）
- Liaoning Academy of Materials（辽宁省材料研究院）
- ShanghaiTech University（上海科技大学）
- National Institute for Materials Science（国立材料研究所）
- Southeast University（东南大学）
- Fudan University（复旦大学）
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