Microscopic Theory of the Single Impurity Surface Kondo Resonance

TL;DR

This paper presents a microscopic theory for the surface Kondo effect, highlighting the momentum dependence of hybridization and its impact on STM conductance, aligning well with experimental observations.

Contribution

It introduces a detailed microscopic model for the surface Kondo effect, emphasizing the role of momentum-dependent hybridization energies and surface-bulk state interactions.

Findings

Hybridization matrix elements depend strongly on momentum around the Fermi surface.

Kondo effect strength can be comparable for surface and bulk states at surfaces.

Theoretical results agree quantitatively with experiments on Co impurities in Cu surfaces.

Abstract

We develop a microscopic theory of the single impurity Kondo effect on a metallic surface. We calculate the hybridization energies for the Anderson Hamiltonian of a magnetic impurity interacting with surface and bulk states and show that, contrary to the Kondo effect of an impurity in the bulk, the hybridization matrix elements are strongly dependent on the momentum around the Fermi surface. Furthermore, by calculating the tunneling conductance of a scanning tunneling microscope (STM), we show that when the magnetic impurity is located at a surface the Kondo effect can occur with equal strength between bulk and surface states. We compare our results with recent experiments of Co impurities in Cu(111) and Cu(100) surfaces and find good quantitative agreement.