Interplay between the Kondo effect and the Ruderman-Kittel-Kasuya-Yosida interaction.

Prüser, Henning; Dargel, Piet E; Bouhassoune, Mohammed; Ulbrich, Rainer G; Pruschke, Thomas; Lounis, Samir; Wenderoth, Martin · Nat Commun · 2014

basic_science · Level V

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Abstract

The interplay between the Ruderman-Kittel-Kasuya-Yosida interaction and the Kondo effect is expected to provide the driving force for the emergence of many phenomena in strongly correlated electron materials. Two magnetic impurities in a metal are the smallest possible system containing all these ingredients and define a bottom-up approach towards a long-term understanding of concentrated/dense systems. Here we report on the experimental and theoretical investigation of iron dimers buried below a Cu(100) surface by means of low-temperature scanning tunnelling spectroscopy combined with density functional theory and numerical renormalization group calculations. The Kondo effect, in particular the width of the Abrikosov-Suhl resonance, is strongly altered or even suppressed due to magnetic coupling between the impurities. It oscillates as a function of dimer separation revealing that it is related to indirect exchange interactions mediated by the conduction electrons.