Abstract

We are currently experiencing a second quantum revolution, where scientists and engineers are working together on the making of new devices which utilize their quantum properties to store and process information. One of the most promising quantum computing platforms developed so far is based on superconducting q-bits. However, superconducting q-bits suffer from decoherence, which impedes the use of the full potential of quantum computers. A possible solution to this drawback are topological superconductors [1], where the quantum states usable for computation are intrinsically protected from decoherence. One of the most promising approaches to the discovery of topological superconductivity is to combine conventional s-wave superconductors with atomic scale spin textures. This approach, based on the building of atomically crafted magnet-superconductor heterostructures (MSHs) [2] is particularly interesting and powerful for two-dimensional (2D) systems, where a plethora of collinear and non-collinear spin textures can be combined with superconducting substrates in order to establish emergent topological superconducting phases.
In the last few years great advancements have been made in the experimental investigation of MSHs where an atomically thin magnetic layer is proximitized to a superconducting substrate [2]. In this presentation, I will discuss how the exchange interaction between a superconducting substrate and a 2D antiferromagnetic [3,4] or nanoscale non-collinear [5] spin texture can give origin to topological nodal point superconductivity. The emergent topological phases are characterized by the formation of topological edge modes at the boundary of the 2D magnetic islands, which are directly observed via spin-polarized scanning tunnelling microscopy and spectroscopy. In particular, I will explain how the presence of a spin spiral in the 2D magnet offers a new knob for the tuning of the dispersion of the topological edge modes, something that was newer observed experimentally before and that holds great potential for application in quantum technologies.

References
[1] M. Sato and Y. Ando, Reports on Progress in Physics 80, 076501 (2017).
[2] R. Lo Conte et al., La Rivista del Nuovo Cimento 47, 453-554 (2024).
[3] R. Lo Conte et al., Physical Review B 105, L100406 (2022).
[4] M. Bazarnik et al., Nature Communications 14, 614 (2023).
[5] R. Brüning et al., ACS Nano 19, 36125-36222 (2025).