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

TL;DR

This study explores how the RKKY interaction influences the Kondo effect in magnetic impurity dimers, combining experimental STM data with theoretical DFT and NRG calculations to reveal oscillatory behavior linked to impurity separation.

Contribution

It provides a combined experimental and theoretical analysis of RKKY-Kondo interplay in magnetic dimers, highlighting the oscillatory suppression of the Kondo effect due to magnetic coupling.

Findings

Kondo resonance width is strongly affected by impurity coupling.

Oscillations in Kondo effect correlate with impurity separation.

DFT simulations support experimental RKKY interaction observations.

Abstract

The interplay between the Ruderman-Kittel-Kasuya-Yosida (RKKY) 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 (STS) combined with density functional theory (DFT) and numerical renormalization group (NRG) 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 function of dimer separation revealing that it is related to the RKKY interaction mediated by the conduction electrons. Simulations based on density functional theory support this concept showing the same oscillation period and trends in the coupling strength as found in the experiment.