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Research Zernike (ZIAM) News Seminars

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 [5]. 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 [9], 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.

[1] S. Nadj Perge et al., Science 346, 602-607 (2014).

[2] H. Kim et al., Sci. Adv. 4, eaar5251 (2018).

[3] A. Palacio-Morales et al., Sci. Adv. 5, eaav6600 (2019).

[4] L. Schneider et al., Nat. Phys. 17, 943-948 (2021).

[5] J. Li et al., Nat. Commun. 7:12297 (2016).

[6] S. Kezilebieke et al., Nature 588, 424 (2020).

[7] A. P. Schnyder, et al., Phys. Rev. B. 78, 195125 (2008).

[8] C. Chiu, et al. Rev. Mod. Phys., 88, 035005 (2016).

[9] R. Lo Conte et al., Phys. Rev. B 105, L100406 (2022).