Efficient algorithm for dispersion of Yu-Shiba-Rusinov chains on a superconducting surface

DIPC Seminars

Speaker

Rik Broekhoven
Delft University of Technology

When

2024/10/15
12:00

Place

DIPC Seminar Room

Host

Nicolás Lorente Palacios

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Magnetic atoms on s-wave superconductors locally suppress superconducting pairing, resulting in Yu-Shiba-Rusinov (YSR) bound states. Chains of YSR states have been proposed to become topological superconductors, when the individual YSR states hybridize and the resulting band is p-wave gapped by spin-orbit coupling. As recently shown through scanning tunneling microscopy experiments, however, realistic systems have many YSR bands and relatively small spin-orbit coupling causing many systems to be topologically trivial. Ab initio models capture the complexity of the realistic system and allow to find the combination of materials and regions of parameter space where the system is topological. The computational costs of these models, however, limit simulations to a finite size of a few nanometers. Thus, simulations must overestimate the superconducting gap to ensure the system is smaller than the superconductor coherence length. We use multi-dimensional Green’s function formalism as an extension to ab initio calculations to go beyond this limit. We reduce the  computational cost of our calculations using short-junction approximation. This allows us to do calculations with realistic gap size as we verify by testing on few orbital YSR models. We apply our tested algorithm to a Mn chain on Nb (110) as in the 2021 experiment of Schneider et al.