A tunable two-impurity Kondo system in an atomic point contact

Jakob Bork, Yong-hui Zhang, Lars Diekhoner, Laszlo Borda, Pascal Simon, Johann Kroha, Peter Wahl, Klaus Kern

Research output: Contribution to journalArticlepeer-review

84 Citations (Scopus)


Two magnetic atoms, one attached to the tip of a scanning tunnelling microscope and one adsorbed on a metal surface, each constituting a Kondo system, have been proposed as one of the simplest conceivable systems potentially exhibiting quantum critical behaviour. We have succeeded in implementing this concept experimentally for cobalt dimers clamped between a scanning tunnelling microscope tip and a gold surface. Control of the tip-sample distance with subpicometre resolution enables us to tune the interaction between the two cobalt atoms with unprecedented precision. Electronic transport measurements on this two-impurity Kondo system reveal a rich physical scenario, which is governed by a crossover from local Kondo screening to non-local singlet formation due to antiferromagnetic coupling as a function of separation of the cobalt atoms.

Original languageEnglish
Pages (from-to)901-906
Number of pages6
JournalNature Physics
Issue number11
Publication statusPublished - Nov 2011


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