Transport properties of a two impurity system: a theoretical approach

TL;DR

This paper presents a theoretical model for a two-impurity system that explains experimental transport phenomena by considering two conduction channels and Kondo resonance hybridization, using advanced many-body techniques.

Contribution

It introduces a microscopic two-impurity Anderson model with a two-path geometry, analyzed through finite-U slave boson and embedded-cluster methods, to explain experimental observations.

Findings

Transport features depend on impurity interactions and conduction channels.

Splitting in conductance is due to hybridization of Kondo resonances.

Model accurately reproduces experimental transport regimes.

Abstract

A system of two interacting cobalt atoms, at varying distances, was studied in a recent scanning tunneling microscope experiment by Bork et. al.[Nature Phys. 7, 901 (2011)]. We propose a microscopic model that explains, for all experimentally analyzed interatomic distances, the physics observed in these experiments. Our proposal is based on the two-impurity Anderson model, with the inclusion of a two-path geometry for charge transport. This many-body system is treated in the finite-U slave boson mean-field approximation and the logarithmic-discretization embedded-cluster approximation. We physically characterize the different charge transport regimes of this system at various interatomic distances and show that, as in the experiments, the features observed in the transport properties depend on the presence of two impurities but also on the existence of two conducting channels for electron transport. We interpret the splitting observed in the conductance as the result of the hybridization of the two Kondo resonances associated with each impurity.