title: Exchange interaction between single magnetic 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 neighboring adatom spins. Increasing the interatomic distance of a Cobalt dimer from 2.56 to 8.1 A 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.
authors.affiliation: Max-Planck-Institut für Festkörperforschung, Heisenbergstrasse 1, 70569 Stuttgart, Germany.
authors.forename: P
authors.initials: P
authors.lastname: Wahl
authors.forename: P
authors.initials: P
authors.lastname: Simon
authors.forename: L
authors.initials: L
authors.lastname: Diekhöner
authors.forename: V S
authors.initials: VS
authors.lastname: Stepanyuk
authors.forename: P
authors.initials: P
authors.lastname: Bruno
authors.forename: M A
authors.initials: MA
authors.lastname: Schneider
authors.forename: K
authors.initials: K
authors.lastname: Kern