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TT: Fachverband Tiefe Temperaturen
TT 51: Topological Superconductors
TT 51.6: Vortrag
Donnerstag, 20. März 2025, 18:00–18:15, H32
Role of Spin-Orbit Coupling on Topological Superconductivity from First Principles — •András Lászlóffy1, Bendegúz Nyári2, Levente Rózsa1, László Szunyogh2, and Balázs Újfalussy1 — 1HUN-REN Wigner Research Centre for Physics, Budapest, Hungary — 2Budapest University of Technology and Economics, Budapest, Hungary
Recent developments on magnetic structures on superconductors paved the way to explore topological phases in real materials [1,2]. This was achieved by solving the Kohn-Sham-Dirac Bogoliubov-de Gennes equations within the Korringa-Kohn-Rostoker multiple scattering theory. By investigating 1D magnetic chains on superconductors we demonstrate that the spin-orbit coupling plays a key role in the formation of a topological phase, however, it is challenging to scale it up, because SOC is implicitly included in the Dirac equation. To circumvent this, we calculate the superconducting order parameter and the Shiba band structure of magnetic chains on a Ta overlayer on Nb. Ta has a very similar crystal structure and lattice constant to Nb. It is also a superconductor with a much smaller gap size and a considerably larger SOC. With varying the Ta layer thickness SOC can be tuned in a way which is in principle reproducible in experiments. We show that a few layers of Ta has tiny effects on the energy of the Yu-Shiba-Rusinov states of single adatoms, however, varying the SOC can tune the chains into a topologically non-trivial domain.
[1] Nyári et. al., PRB 108, 134512 (2023);
[2] Lászlóffy et. al., PRB 108, 134513 (2023).
Keywords: Spin-orbit coupling; Superconductivity; Magnetic chain; Superconducting order parameter; Majorana fermions