发表机构
Indian Institute of Technology Kharagpur（印度理工学院卡拉格普尔分校）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
研究方-八角超导晶格中磁性吸附原子，发现吸附几何通过干涉效应调控平带耦合与磁性束缚态，进而影响亚隙输运电导。
AI 中文摘要
方-八角晶格为研究磁性吸附原子提供了一个有用的平台，因为其多子晶格结构允许不同的吸附几何构型来探测宿主电子态的不同组合。我们研究了s波超导方-八角晶格中的磁性吸附原子，重点关注吸附几何、窄带和平带态以及亚隙输运之间的相互作用。我们发现，与平带相关的大谱权重并不一定意味着强的杂质-宿主耦合。对于对称的方孔吸附，相消干涉强烈抑制了与平带流形的重叠，而顶位和八角孔吸附则保留了显著的重叠。这种选择性反映在磁性束缚态中，方孔通道支持一个主要呈原子性的态，而顶位和八角孔态则与超导宿主强烈杂化。该效应随着相关能带变平而连续发展，并在一个材料驱动的参数区间内保持显著。在正常-超导-正常几何结构中，这些差异也反映在非局域亚隙电导中。在代表性的交换劈裂下，方孔吸附相对于干净器件抑制了低偏压电导，而八角孔吸附则增强了电导，且方孔响应对交换劈裂的依赖性更为陡峭。我们的结果表明，窄带和平带超导体中的磁性吸附原子响应由可用的谱权重以及杂质-宿主杂化的对称性和波函数结构所决定。
英文摘要
The square--octagon lattice provides a useful setting for studying magnetic adatoms because its multisublattice structure allows different adsorption geometries to probe distinct combinations of the host electronic states. We study magnetic adatoms in an $s$-wave superconducting square--octagon lattice, focusing on the interplay between adsorption geometry, narrow and flat-band states, and subgap transport. We find that the large spectral weight associated with a flat band does not necessarily imply strong impurity--host coupling. For symmetric square-hollow adsorption, destructive interference strongly suppresses the overlap with the flat-band manifold, whereas top and octagon-hollow adsorption retain substantial overlap. This selectivity is reflected in the magnetic bound states, with the square-hollow channel supporting a predominantly atomic state, while the top and octagon-hollow states are strongly hybridized with the superconducting host. The effect develops continuously as the relevant band becomes flatter and remains pronounced in a material-motivated parameter regime. In a normal--superconductor--normal geometry, these differences are also reflected in the nonlocal subgap conductance. At a representative exchange splitting, square-hollow adsorption suppresses the low-bias conductance relative to the clean device, whereas octagon-hollow adsorption enhances it, with the square-hollow response showing a much sharper dependence on exchange splitting. Our results show that the magnetic-adatom response in narrow and flat-band superconductors is governed by the available spectral weight and by the symmetry and wave-function structure of the impurity--host hybridization.
Comments11 pages, 11 figures
