Exchange interaction between single magnetic adatoms

TL;DR

This study investigates the magnetic interactions between single cobalt adatoms on a copper surface by analyzing the Kondo resonance, revealing oscillatory magnetic coupling and collective states as adatoms are added or spaced differently.

Contribution

It demonstrates how the magnetic coupling between adatoms can be tuned and characterized through Kondo resonance measurements, highlighting oscillatory behavior and collective state formation.

Findings

Oscillatory transition from ferromagnetic to antiferromagnetic coupling with increasing adatom distance.

Modification of Kondo resonance reflects changes in magnetic coupling.

Formation of collective correlated states with multiple adatoms.

Abstract

The magnetic coupling between single Co atoms adsorbed on a copper surface is determined by probing the Kondo resonance using low-temperature scanning tunneling spectroscopy. The Kondo resonance, which is due to magnetic correlation effects between the spin of a magnetic adatom and the conduction electrons of the substrate, is modified in a characteristic way by the coupling of the neighbouring adatom spins. Increasing the interatomic distance of a Cobalt dimer from 2.56A to 8.1A we follow the oscillatory transition from ferromagnetic to antiferromagnetic coupling. Adding a third atom to the antiferromagnetically coupled dimer results in the formation of a collective correlated state.