Theory of differential conductance of Co on Cu(111) including Co s and d orbitals, and surface and bulk Cu states

TL;DR

This paper develops a comprehensive theoretical model for the differential conductance observed in STM experiments on Co atoms on Cu(111), incorporating multiple orbitals and conduction states to explain the Kondo effect features.

Contribution

It introduces a detailed theoretical framework including Co s and d orbitals and surface and bulk Cu states to interpret STM measurements of the Kondo effect.

Findings

STM mainly senses the Co s orbital

Kondo antiresonance results from interference between s and d orbitals

Model successfully fits experimental differential conductance data

Abstract

We revisit the theory of the Kondo effect observed by a scanning-tunneling microscope (STM) for transition-metal atoms (TMAs) on noble-metal surfaces, including $d$ and $s$ orbitals of the TMA, surface and bulk conduction states of the metal, and their hoppingto the tip of the STM. Fitting the experimentally observed STM differential conductance for Co on Cu(111) including both, the Kondo feature near the Fermi energy and the resonance below the surface band, we conclude that the STM senses mainly the Co $s$ orbital and that the Kondo antiresonance is due to interference between states with electrons in the $s$ orbital and a localized $d$ orbital mediated by the conduction states.