The Noncollinear Path to Two-Dimensional Topological Superconductivity

Two-dimensional magnet-superconductor hybrids (2D-MSH) are promising candidates to realize devices for topology-based quantum technologies and superconducting spintronics. So far, studies have focused on 2D-MSH systems with collinear ferro- or antiferromagnetic layers. Here, we present the discovery of topological superconductivity in a noncollinear MSH system where a magnetic spiral is realized in an Fe monolayer proximity coupled to a superconducting Ta(110) substrate. By combining low-temperature spin-polarized scanning tunneling spectroscopy with an in-depth theoretical study, we can conclude that the system is in a topological nodal-point superconducting phase with low-energy edge modes. Furthermore, we reveal that for this noncollinear spin texture, these edge modes exhibit a magnetization direction-dependent dispersion. This means that a spatial shift of the magnetic spiral could be used to reverse the chirality of an edge mode in future MSH-based devices.. Authors: Brüning, Reiner [Univ. of Hamburg (Germany)]; Bedow, Jasmin [Univ. of Illinois, Chicago, IL (United States)] (ORCID:0000000220108567); Lo Conte, Roberto [Univ. of Hamburg (Germany); Univ. of Groningen (Netherlands)] (ORCID:0000000250509978); von Bergmann, Kirsten [Univ. of Hamburg (Germany)] (ORCID:0000000245143254); Morr, Dirk K. [Univ. of Illinois, Chicago, IL (United States)]. DOE Contract: FG02-05ER46225. Subjects: chiral edge modes; noncollinear magnet-superconductor hybrids; spin spirals; spin-polarized scanning tunneling spectroscopy; topological nodal-point superconductors