发表机构
Indiana University; The University of Danang, University of Science and Technology（印第安纳大学; 岘港大学科学技术大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
该研究通过密度泛函理论和双层紧束缚模型，揭示FeSn中平带源于层间Fe-Fe反键耦合而非孤立kagome层，确立了层间耦合和磁堆叠为调控平带的关键参数。
AI 中文摘要
Kagome金属FeSn在其终止表面表现出占据的平带，而块体FeSn采用A型反铁磁序且不显示相同特征。这里，我们结合密度泛函理论、原胞与双倍胞分析以及双层紧束缚模型，以确定层间电子耦合和磁堆叠如何控制FeSn中平带的形成。我们在铁磁态中识别出一个占据的Fe-$d_{z^2}$衍生的平带流形，与实验观察到的表面特征一致。布里渊区折叠揭示其平带分支起源于原胞的$k_z=\frac{\pi}{c}$扇区，表明它不能被视为孤立的kagome层态。相反，该态依赖于相邻kagome层之间的耦合，并可视为最近邻kagome层之间反键耦合的结果。双层紧束缚分析确定层间Fe-Fe跳跃是导致该行为的主要微观耦合，而对比性的未占据平带相关流形则主要由层内Fe-Sn杂化控制。这些结果确立了层间耦合和磁堆叠作为kagome平带的关键控制参数，并强调了层间耦合如何在量子材料中产生和调控扩展的关联电子态。
英文摘要
Kagome FeSn exhibits an occupied flat band at its terminated surface, whereas bulk FeSn adopts A-type antiferromagnetic order and does not display the same feature. Here, we combine density functional theory with primitive- and doubled-cell analysis and a double-layer tight-binding model to determine how interlayer electronic coupling and magnetic stacking control flat-band formation in FeSn. We identify an occupied Fe-$d_{z^2}$-derived flat-band manifold in the ferromagnetic state that is consistent with the experimentally observed surface feature. Brillouin-zone folding reveals that its flat branch originates from the $k_z=\fracπ{c}$ sector of the primitive cell, demonstrating that it cannot be understood as an isolated kagome-layer state. Instead, the state depends on coupling between neighboring kagome layers and can be seen as a result of antibonding coupling between nearest neighbor kagome layers. A double-layer tight-binding analysis identifies interlayer Fe-Fe hopping as the dominant microscopic coupling responsible for this behavior, while a contrasting unoccupied flat-band-related manifold is governed primarily by intralayer Fe-Sn hybridization. These results establish interlayer coupling and magnetic stacking as key control parameters for kagome flat bands and highlight how coupling between layers can generate and tune extended correlated-electron states in quantum materials.
