Topological nodal-point superconductivity in a 2D-antiferromagnet/superconductor hybrid system

In the recent years, pioneering studies have been carried out on magnet/superconductor hybrid systems [1-4], motivated by their potential to host emergent quantum phases such as topological superconductivity [5]. So far, the attention has been mainly focused on hybrid systems with a ferromagnetic order [1,3,4,6], which are understood as gapped topological superconductors with a finite Chern number [7,8] defining the amount of end states and propagating edge modes.

Here, we present the discovery of a topological nodal-point superconducting phase in a hybrid system consisting of antiferromagnetic manganese (Mn) monolayer islands on top of the s-wave superconductor niobium (Nb) [9]. The novel topological superconducting phase was discovered via a low-temperature spin-polarized scanning tunneling microscopy and spectroscopy investigation. Low-energy edge modes are observed at the boundaries of the magnetic islands, separating the topological phase from the trivial one. In accordance to tight-binding calculations, we find that the relative spectral weight of the edge modes depends on the edge’s atomic configuration, which is a fingerprint of the discovered topological superconducting state. Our results establish the combination of antiferromagnetism and superconductivity as a novel route to design 2D topological quantum phases.



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