Magnetic bound states in 2D superconductors

磁吸附态在超导体上的交换耦合产生Yu-Shiba-Rusinov态。它们在三维超导体上迅速衰变。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信号。在某些参数范围内，扩展结构有望承载拓扑边缘状态。为了克服块体三维超导体上有限的相互作用范围，我们将生长和表征基于二维超导体的异质结构。我们将受益于其中一个合作伙伴在分子束外延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态从单分子吸附到NbSe2和Re上石墨烯单层上的二维岛的演变。分子吸附剂选择的灵活性为不同的磁矩、不同的表面交换耦合以及底物介导的分子间耦合强度提供了很大的参数空间。这将使我们能够探索大范围的磁相图和寻找拓扑态。此外，我们还将生长原子薄层NbSe2和磁性过渡金属二卤化物的异质结构。在这里，磁性层的选择允许我们调整与衬底的交换耦合强度。我们还将研究岛屿大小对拓扑边态可能性的影响，并最终调查相邻岛屿之间的相互作用。我们对二维超导体上磁性金属-有机和无机层的YSR态的系统分析将使我们能够对与衬底的交换耦合以及外延层的磁性织构有基本的了解。我们的见解可能有助于寻找二维超导体异质结构中的拓扑态。

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.