Long-range Kondo signature of a single magnetic impurity

TL;DR

This paper reports the discovery of a long-range Kondo effect signature from single magnetic impurities buried under a surface, supported by experimental data and theoretical modeling, challenging previous notions of rapid decay of Kondo features.

Contribution

It reveals a previously unobserved long-range Kondo signature for buried magnetic atoms, combining experimental STS data with advanced theoretical calculations.

Findings

Long-range Kondo signatures observed for buried Fe and Co atoms.

Theoretical band structure and NRG calculations match experimental data.

Kondo features persist over larger distances than previously thought.

Abstract

The Kondo effect, one of the oldest correlation phenomena known in condensed matter physics, has regained attention due to scanning tunneling spectroscopy (STS) experiments performed on single magnetic impurities. Despite the sub-nanometer resolution capability of local probe techniques one of the fundamental aspects of Kondo physics, its spatial extension, is still subject to discussion. Up to now all STS studies on single adsorbed atoms have shown that observable Kondo features rapidly vanish with increasing distance from the impurity. Here we report on a hitherto unobserved long range Kondo signature for single magnetic atoms of Fe and Co buried under a Cu(100) surface. We present a theoretical interpretation of the measured signatures using a combined approach of band structure and many-body numerical renormalization group (NRG) calculations. These are in excellent agreement with the rich spatially and spectroscopically resolved experimental data.