QuMat seminar

Density functional Bogoliubov-de Gennes calculations for a topological superconductor

Speaker: Philipp Rüßmann – Forschungszentrum Jülich Host: Zeila Zanolli


The possibility to combine topological electronic band structures and superconductivity (SC) opens new pathways towards engineering exotic quantum matter. Proximity-induced SC in the topological surface state of topological insulators (TIs) offers the possibility to realize a chiral 𝑝-wave superconductor. This is an exotic state of matter which supports non-Abelian anyons and is of great interest for Majorana-based quantum computing applications. Material-specific insights into the microscopic details of such SC/TI interfaces are of great interest and an indispensable ingredient in the challenging materials optimization problem. Here we first introduce the recent Bogoliubov de-Gennes (BdG) extension to the all electron full potential relativistic Korringa-Kohn-Rostoker (KKR) Green function code juKKR [1,2]. This KKR-BdG method allows a description of inhomogeneous superconductors on the basis of density functional theory. We apply this method to the 𝑠 -wave superconductor Nb and study its (110) surface [1]. We then turn to the investigation of the proximity effect in Nb/TI interfaces and discuss the induced superconductivity in the topological surface state of this SC/TI heterostructure [3].

This work was supported by the ML4Q Cluster of Excellence (EXC 2004/1 – 390534769) and by the Bavarian Ministry of Economic Affairs, Regional Development and Energy within Bavaria’s High-Tech Agenda Project “Bausteine für das Quantencomputing auf Basis topologischer Materialien mit experimentellen und theoretischen Ansätzen” (grant allocation no. 07 02/686 58/1/21 1/22 2/23).

[1] Philipp Rüßmann and Stefan Blügel, Phys. Rev. B 105, 125143 (2022)
[2] The juKKR code package, https://jukkr.fz-juelich.de
[3] Philipp Rüßmann and Stefan Blügel, arXiv:2208.14289 (2022)

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