Mapping Itinerant Electrons around Kondo Impurities

TL;DR

This study uses low temperature scanning tunneling spectroscopy to map the local density of states around buried Fe and Co impurities in Cu(100), revealing anisotropic oscillations in the Kondo resonance related to itinerant electron behavior.

Contribution

It provides a detailed spatial mapping of the Kondo resonance around buried impurities, highlighting anisotropic oscillations and separating impurity physics from measurement effects.

Findings

Oscillatory behavior of the Kondo resonance with impurity depth and lateral distance.

Anisotropic spectral function of itinerant electrons.

Spatially resolved mapping of Kondo effects around buried impurities.

Abstract

We investigate single Fe and Co atoms buried below a Cu(100) surface using low temperature scanning tunneling spectroscopy. By mapping the local density of states of the itinerant electrons at the surface, the Kondo resonance near the Fermi energy is analyzed. Probing bulk impurities in this well-defined scattering geometry allows separating the physics of the Kondo system and the measuring process. The line shape of the Kondo signature shows an oscillatory behavior as a function of depth of the impurity as well as a function of lateral distance. The oscillation period along the different directions reveals that the spectral function of the itinerant electrons is anisotropic.