# Kondo behavior and conductance through $3d$ impurities in gold chains doped with oxygen

## TL;DR

This paper investigates the Kondo effect and conductance properties in oxygen-doped gold chains with 3d transition-metal impurities, revealing complex screening behaviors and potential non-Fermi liquid phenomena.

## Contribution

It combines ab initio calculations with effective models to analyze how oxygen doping influences magnetic screening and conductance in gold chains with 3d impurities, identifying various Kondo regimes.

## Key findings

- Most 3d impurities exhibit underscreened Kondo physics with singular Fermi liquid behavior.
- Fe and Co impurities may show non-Fermi liquid behavior under certain crystal fields.
- Ni and Cu impurities are described by two-channel Kondo and SU(4) Anderson models, respectively.

## Abstract

Combining ab initio calculations and effective models derived from them, we discuss the electronic structure of oxygen doped gold chains when one Au atom is replaced by any transition-metal atom of the $3d$ series. The effect of O doping is to bring extended Au $5d_{xz}$ and $5d_{yz}$ states to the Fermi level, which together with the Au states of zero angular momentum projection, lead to three possible channels for the screening of the magnetism of the impurity. For most 3d impurities the expected physics is similar to that of the underscreened Kondo model, with singular Fermi liquid behavior. For Fe and Co under a tetragonal crystal field introduced by leads, the system might display a non-Fermi liquid behavior. Ni and Cu impurities are described by a $S = 1$ two channel Kondo model and an SU(4) impurity Anderson model in the intermediate valence regime, respectively. In both cases, the system is a Fermi liquid, but the conductance shows some observable differences with the ordinary SU(2) Anderson model.