发表机构
Hong Kong University of Science and Technology; Peking University; Fudan University; Hefei National Laboratory（香港科技大学; 北京大学; 复旦大学; 合肥国家实验室）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本工作提出利用莫尔工程在反铁磁薄膜中实现量子层霍尔效应，通过控制层产生超晶格势，实现量子化的层霍尔电导，并揭示其微观机制为层-U(1)规范场产生的赝磁场。
AI 中文摘要
偶数层拓扑反铁磁薄膜（如MnBi$_2$Te$_4$）表现出一种由层锁定贝里曲率引起的非常规层霍尔效应（LHE）。该效应表现为层极化的反常霍尔效应，可通过垂直位移场进行调控。然而，实现量子化的LHE在实验上仍具挑战性。在本工作中，我们提出利用莫尔工程，通过控制层产生的静电超晶格势，可以实现量子层霍尔效应（QLHE）。具体而言，将莫尔控制层紧密放置在MnBi$_2$Te$_4$薄膜表面附近而不破坏$PT$对称性，所得系统表现出消失的总霍尔电导但量子化的层霍尔电导$e^2/h$。随后，弱的栅极电场破坏$PT$对称性，驱动系统进入层极化的量子反常霍尔（QAH）相。此外，当仅在单个表面引入单个控制层时，即使没有外部电场，层极化QAH也会出现。我们将QLHE的微观起源识别为标量莫尔势产生的涌现层-$U(1)$规范场，该场在顶层和底层产生相反的周期性赝磁场。我们的工作为实现反铁磁薄膜中的QLHE提供了可行途径。
英文摘要
Even-layer topological antiferromagnetic thin films such as MnBi$_2$Te$_4$ exhibit an unconventional layer Hall effect (LHE) arising from a layer-locked Berry curvature. This effect manifests as a layer-polarized anomalous Hall effect that can be controlled by a vertical displacement field. However, achieving a quantized version of the LHE remains experimentally challenging. In this work, we propose that moiré engineering, using an electrostatic superlattice potential from control layers, can realize the quantum layer Hall effect (QLHE). Specifically, by placing moiré control layers in close proximity to the surfaces of a MnBi$_2$Te$_4$ thin film without breaking $PT$ symmetry, the resulting system exhibits a vanishing net Hall conductance but a quantized layer Hall conductance of $e^2/h$. A weak gate electric field then breaks $PT$ symmetry and drives the system into a layer-polarized quantum anomalous Hall (QAH) phase. Furthermore, when a single control layer is introduced on only one surface, the layer-polarized QAH emerges even in the absence of an external electric field. We identify the microscopic origin of the QLHE as an emergent layer-$U(1)$ gauge field generated by the scalar moiré potential, which in turn produces opposite periodic pseudomagnetic fields on the top and bottom layers. Our work provides a feasible pathway toward realizing the QLHE in antiferromagnetic thin films.
Comments7 pages, 6 figures
