Two-dimensional Shiba lattices as a possible platform for crystalline topological superconductivity

One-dimensional chains of magnetic adatoms on the surface of a superconductor have been claimed to host topological states. Now, this idea is extended to two-dimensional systems. Localized or propagating Majorana boundary modes are the key feature of topological superconductors. They are rare in naturally occurring compounds, but the tailored manipulation of quantum matter offers opportunities for their realization. Specifically, lattices of Yu-Shiba-Rusinov bound states-Shiba lattices-that arise when magnetic adatoms are placed on the surface of a conventional superconductor can be used to create topological bands within the superconducting gap of the substrate. Here we reveal two signatures consistent with the realization of two types of mirror-symmetry-protected topological superconductor using scanning tunnelling microscopy to create and probe adatom lattices with single-atom precision. The first has edge modes as well as higher-order corner states, and the second has symmetry-protected bulk nodal points. In principle, their topological character and boundary modes should be protected by the spatial symmetries of the adatom lattice. Our results highlight the potential of Shiba lattices as a platform to design the topology and sample geometry of two-dimensional superconductors.

Automated summary

Scientists have extended the idea of the one-dimensional magnetic adatom chain structure to two-dimensional systems, which may host topological states. By placing magnetic adatoms on the surface of a conventional superconductor, lattices of Yu-Shiba-Rusinov bound states can be formed to create topological bands within the superconducting gap.