Topological superconductivity in a multichannel Yu-Shiba-Rusinov chain

TL;DR

This paper investigates how multichannel Yu-Shiba-Rusinov chains on superconductors with strong spin-orbit coupling can host topological states with Majorana modes, highlighting the role of multiple bands in expanding topological phase space.

Contribution

It introduces a realistic multichannel model for Yu-Shiba-Rusinov chains, revealing how higher bands and spin-orbit coupling influence topological phases.

Findings

Multiple bands can significantly enlarge the topological phase space.

Higher scattering channels enhance the robustness of topological states.

The phase diagram depends critically on the interplay of channels and spin-orbit coupling.

Abstract

Chains of magnetic atoms placed on the surface of an s-wave superconductor with large spin-orbit coupling provide a promising platform for the realization of topological superconducting states characterized by the presence of Majorana zero-energy modes. In this work we study the properties of the one-dimensional chain of Yu-Shiba-Rusinov states induced by magnetic impurities using a realistic model for the magnetic atoms that include the presence of multiple scattering channels. These channels are mixed by the spin-orbit coupling and, via the hybridization of the Yu-Shiba-Rusinov states at different sites of the chain, result in a multi-band structure for the chain. We obtain the topological phase diagram for such band structure. We identify the parameter regimes for which the different bands lead to a topological phase and show that the inclusion of higher bands can greatly enlarge the phase space for the realization of topological states.