Systematic study of Mn atoms, artificial dimers and chains on superconducting Ta(110)

TL;DR

This study systematically investigates Mn adatoms, dimers, and chains on superconducting Ta(110), analyzing their electronic and magnetic properties to inform the design of topological superconducting chains, with comparisons to Nb(110).

Contribution

It provides detailed insights into the hybridization, splitting, and spin structures of Mn adatoms and chains on Ta(110), a less explored superconductor with strong spin-orbit coupling.

Findings

Splitting and hybridization depend on crystallographic direction and interatomic spacing.

Mn chains exhibit length-dependent Shiba band structures.

Comparison shows differences due to spin-orbit interaction strength.

Abstract

Magnetic adatoms coupled to an $s$-wave superconductor give rise to local bound states, so-called Yu-Shiba-Rusinov states. Focusing on the ultimate goal of tailoring chains of such adatoms into a topologically superconducting phase, we investigate basic building blocks - single Fe and Mn adatoms and Mn dimers on clean superconducting Ta(110) - using scanning tunneling microscopy and spectroscopy. We perform a systematic study of the hybridizations and splittings in dimers, and their dependence on the crystallographic directions and interatomic spacings, in order to identify potentially interesting chain geometries for this novel sample type. Subsequently, we study the spin structure as well as the length dependent Shiba band structure in Mn chains of those geometries using spin-resolved scanning tunneling spectroscopy. All results are compared to the according properties of structurally identical dimers and chains on the previously studied Nb(110), which has almost identical surface structure and electronic properties, but an about three times smaller spin-orbit interaction.