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

TL;DR

This study demonstrates that Majorana modes in Fe chains on a superconducting Rashba alloy are robust against potential disorder, supporting their potential use in fault-tolerant quantum computing.

Contribution

The paper provides experimental evidence that Majorana modes remain stable despite nano-scale potential disorder in Fe chains on a superconducting surface.

Findings

Zero-energy Majorana modes appear at chain ends despite disorder

Majorana modes are topologically protected and robust against potential disorder

Experimental results align with tight-binding calculations confirming topological regime

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.