Magnetic bound states in 2D superconductors

磁性吸附在超导体上的交换耦合诱导了Yu-Shiba-Rusinov （YSR）态。这些在三维超导体上迅速衰减。相反，二维超导体增加了衰变长度，从而增强了YSR态的耦合。耦合YSR态的分裂和位移提供了杂化和磁相互作用的特征。在某些参数条件下，扩展结构被认为具有拓扑边缘状态。为了克服块体三维超导体上有限的相互作用范围，我们将在二维超导体的基础上生长和表征异质结构。我们将受益于其中一个合作伙伴在MBE生长方面的专业知识，而其他合作伙伴将使用高分辨率扫描隧道显微镜来跟踪YSR状态的演变，从单分子吸附到NbSe2和石墨烯在铼上的单层二维岛屿。分子吸附物选择的灵活性为不同磁矩、与表面的不同交换偶联以及底物介导的分子间偶联强度提供了较大的参数空间。这将使我们能够探索大范围的磁相图和搜索拓扑状态。此外，我们将培养NbSe2和磁性过渡金属二硫族化合物的原子薄层异质结构。在这里，磁性层的选择允许我们调整基片的交换耦合强度。我们还将研究岛屿大小对拓扑边缘状态可能性的影响，并最终研究相邻岛屿之间的相互作用。我们对二维超导体上磁性金属有机层和无机层的YSR态的系统分析将使我们对基材的交换耦合以及衬底的磁性结构有基本的了解。我们的见解可能有助于寻找二维超导体异质结构的拓扑状态。

Exchange coupling of magnetic adsorbates on superconductors induces Yu-Shiba-Rusinov (YSR) states. These decay rapidly on a three-dimensional superconductor. In contrast, a two-dimensional superconductor enhances the decay length and, thus, enhances coupling of YSR states. The splitting and shift of coupled YSR states provide signatures of hybridization and magnetic interactions. In certain parameter regimes, extended structures are expected to host topological edge states. To overcome the limited range of interactions on bulk three-dimensional superconductors, we will grow and characterize heterostructures based on two-dimensional superconductors. We will profit from the expertise in MBE growth of one of the partners, while the other partners will use high-resolution scanning tunneling microscopy to track the evolution of the YSR states from single molecular adsorbates to two-dimensional islands on monolayers of NbSe2 and graphene on Rhenium. The flexibility in the choice of molecular adsorbate provides a large parameter space for different magnetic moments, different exchange coupling to the surface, as well as substrate-mediated intermolecular coupling strength. This will allow us to explore a large range of the magnetic phase diagram and search for topological states. Additionally, we will grow heterostructures of atomically thin layers of NbSe2 and magnetic transition-metal dichalcogenides. Here, the choice of the magnetic layer allows us to tune the exchange coupling strength to the substrate. We will also investigate the influence of the island size on the possibility of topological edge states and eventually investigate the interaction of adjacent islands. Our systematic analysis of YSR states of magnetic metal-organic and inorganic layers on two-dimensional superconductors will enable fundamental insights into exchange coupling to the substrate as well as magnetic textures of the adlayers. Our insights may help in the search for topological states in heterostructures of two-dimensional superconductors.