Dresden 2026 – scientific programme
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O: Fachverband Oberflächenphysik
O 15: Spins on surfaces at the atomic scale I
O 15.8: Talk
Monday, March 9, 2026, 17:00–17:15, WILL/A317
Robustness of zero-energy edge states to disorder in bottom-up designed Fe chains on a superconducting Rashba alloy — •Harim Jang1, Daniel Crawford2, Jens Wiebe1, Stephan Rachel3, and Roland Wiesendanger1 — 1Department of Physics, University of Hamburg, Hamburg, Germany — 2Department of Physics and Nanoscience Center, University of Jyväskylä, Finland — 3School of Physics, University of Melbourne, Parkville, Australia
In this talk, we report on the role of disorder for the observation of Majorana zero modes (MMs) and a topological gap in a tailored 1D magnet-superconductor hybrid (MSH) system, showing the robustness of MMs to disorder, even in cases for which the topological gap is fully suppressed. We constructed 1D spin chains from Fe atoms on the Rashba surface alloy BiAg2/Ag(111) with proximity-induced superconductivity from a Nb(110) substrate. While the Fe chains have perfect crystalline order by design, the BiAg2/Ag(111) film exhibits nano-scale potential disorder, observed by scanning tunneling microscopy. However, this doesn't prevent the emergence of zero-energy states at the Fe chain's ends, in agreement with tight-binding calculations which show that they only appear in the topologically non-trivial regime [1]. This may not only explain earlier observations of MMs in disordered MSH systems, but also provides novel perspectives for the realization of robust Majorana qubits. [1] H. Jang et al., arXiv:2506.17414 (2025)
Keywords: Topological superconductor; Majorana mode; scanning tunneling microscopy; Tight-binding calculation; Potential disorder