通量失配Hofstadter双层中的拓扑调控

中文摘要 AI 辅助

堆叠的二维材料为电控拓扑电子态提供了一个有前景的平台。然而，层间隧穿会使能带杂化，并移除改变拓扑所需的交叉点。我们表明，情况并非总是如此。在层间经历不同磁通量的Hofstadter双层中，能带交叉及其相关的Weyl点受到拓扑约束。当共振磁Bloch多重态携带不相等的Chern数时，其投影隧穿受到拓扑阻碍，并且必须在孤立动量处消失。通过层偏压扫过这些零点，在动量-偏压空间中产生合成Weyl单极子，从而转移Chern数失配。我们展示了两个结果：绝缘Chern相之间的直接转变，以及一个可重入的补偿金属，其中Lifshitz转变限制了金属窗口，而内部Weyl事件重构了能带拓扑。因此，即使整数Chern数在能带之间转移，固定填充的Hall响应仍保持连续且非量子化。Berry通量、TKNN和界面计算独立验证了该机制及其多通道手性特征。我们概述了在Moiré和反常Hall异质结构中的实现，确立了通量失配作为电可编程Chern相和手性输运的实验可及途径。

英文摘要

Stacked two-dimensional materials provide a promising platform for electrically controlling topological electronic states. However, tunneling between layers hybridizes their bands and removes the crossings needed to change topology. We show that this does not always have to be the case. Band crossings and associated Weyl points are topologically enforced in Hofstadter bilayers whose layers experience different magnetic fluxes. When resonant magnetic Bloch multiplets carry unequal Chern numbers, their projected tunneling is topologically obstructed and must vanish at isolated momenta. Sweeping the layer bias through these zeros creates synthetic Weyl monopoles in momentum-bias space that transfer the Chern mismatch. We demonstrate two consequences: a direct transition between insulating Chern phases and a reentrant compensated metal in which Lifshitz transitions bound the metallic window while internal Weyl events reconstruct the band topology. Consequently, the fixed-filling Hall response remains continuous and nonquantized even as integer Chern number is transferred between bands. Berry-flux, TKNN, and interface calculations independently verify the mechanism and its multichannel chiral signature. We outline realizations in Moire and anomalous-Hall heterostructures, establishing flux mismatch as an experimentally accessible route to electrically programmable Chern phases and chiral transport.

发表机构

• Texas A&M University（德州农工大学）

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9 pages, 7 figures