Dr. Roberto Lo Conte - Topological nodal-point superconductivity in a magnet/superconductor hybrid system
|When:||Tu 12-07-2022 09:30 - 10:00|
In the last few 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 . So far, the attention has been mainly focused on 1D and 2D 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, respectively.
In this talk, I will discuss the discovery of a topological nodal-point superconducting phase in a hybrid system consisting of antiferromagnetic manganese (Mn) monolayers on top of the s-wave superconductor niobium (Nb). The novel topological superconducting phase was discovered via a low-temperature spin-polarized scanning tunneling microscopy and spectroscopy investigation. In addition to the presence of proximity-induced superconductivity in the antiferromagnetic Mn layer , we also observe low-energy edge modes 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.
 S. Nadj Perge et al., Science 346, 602-607 (2014).
 H. Kim et al., Sci. Adv. 4, eaar5251 (2018).
 A. Palacio-Morales et al., Sci. Adv. 5, eaav6600 (2019).
 L. Schneider et al., Nat. Phys. 17, 943-948 (2021).
 J. Li et al., Nat. Commun. 7:12297 (2016).
 S. Kezilebieke et al., Nature 588, 424 (2020).
 A. P. Schnyder, et al., Phys. Rev. B. 78, 195125 (2008).
 C. Chiu, et al. Rev. Mod. Phys., 88, 035005 (2016).
 R. Lo Conte et al., Phys. Rev. B 105, L100406 (2022).