Robustness of Majorana modes to potential disorder in Fe chains on a superconducting Rashba alloy

Harim Jang; Daniel Crawford; Khai Ton That; Lucas Schneider; Jens Wiebe; Makoto Shimizu; Harald O. Jeschke; Stephan Rachel; Roland Wiesendanger

arXiv · 2506.17414

Robustness of Majorana modes to potential disorder in Fe chains on a superconducting Rashba alloy

Harim Jang·Daniel Crawford·Khai Ton That·Lucas Schneider·Jens Wiebe·Makoto Shimizu·Harald O. Jeschke·Stephan Rachel·Roland Wiesendanger

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Abstract

Majorana modes offer great potential for fault-tolerant quantum computation due to their topological protection. However, for superconductor-semiconductor nanowire hybrids, intrinsic disorder makes the unambiguous detection of Majorana modes difficult. Here, we construct 1D spin chains from individual Fe atoms on the Rashba surface alloy BiAg2/Ag(111) with proximity-induced superconductivity from a Nb(110) substrate. While the Fe chains exhibit perfect crystalline order, we observe nano-scale potential disorder of the BiAg2/Ag(111)/Nb(110) heterostructure by scanning tunneling microscopy. However, this does not prevent the emergence of zero-energy modes at both ends of the Fe chains, in agreement with tight-binding calculations showing that they are only found in the topologically non-trivial regime of the phase diagram. These Majorana modes are indeed robust against potential disorder.

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Harim Jang, Daniel Crawford, Khai Ton That, Lucas Schneider, Jens Wiebe, Makoto Shimizu, Harald O. Jeschke, Stephan Rachel, Roland Wiesendanger. 2025-06-20. Robustness of Majorana modes to potential disorder in Fe chains on a superconducting Rashba alloy. https://arxiv.org/abs/2506.17414

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