Rare-earth atoms on Nb(110) as a platform to engineer topological superconductivity

TL;DR

This study demonstrates that gadolinium adatoms on Nb(110) can host Yu-Shiba-Rusinov states and form stable chiral spin-spirals, providing a new platform to engineer topological superconductivity and Majorana modes.

Contribution

It reveals how rare-earth Gd atoms on Nb(110) induce specific magnetic states and interactions, advancing the design of topological superconducting systems.

Findings

Gd adatoms create Yu-Shiba-Rusinov states on Nb(110)

Gd chains can form stable chiral spin-spirals

Rare-earth magnets enable tuning of spin-spiral ground states

Abstract

Helical spin textures in one-dimensional magnetic chains on superconductors can enable topological superconductivity and host Majorana zero modes, independent of the presence of intrinsic spin-orbit coupling. Here, we show that gadolinium (Gd) adatoms, possessing large 4f magnetic moments when placed on a Nb(110) surface, establish indirect exchange interactions mediated by valence electrons, manifesting as Yu-Shiba-Rusinov states. By combining scanning tunneling microscopy and spectroscopy with density functional theory, we analyze the emergence of the Yu-Shiba-Rusinov states in single Gd atoms and Gd dimers and uncover the underlying magnetic interaction mechanisms, on the basis of which we predict by means of spin-dynamics simulations the formation of stable chiral N\'eel-type spin-spiral configurations in Gd chains. These findings highlight rare-earth magnets as a promising platform for precisely tuning spin-spiral ground states, an essential prerequisite for the realization of topological superconductivity.