Two-Site Kondo Effect in Atomic Chains

TL;DR

This paper investigates the two-site Kondo effect in atomic chains, demonstrating how the Kondo temperature oscillates with chain length and is influenced by magnetic interactions mediated by the Cu atoms.

Contribution

It provides experimental and theoretical insights into how the Kondo effect varies with atomic chain length and magnetic interactions, revealing tunable two-site Kondo behavior.

Findings

Kondo temperature oscillates with chain length n for n>=3

RKKY interaction mediates oscillations in T_K

Ferromagnetic and antiferromagnetic interactions observed for n=1 and 2

Abstract

Linear CoCu_nCo clusters on Cu(111) are fabricated by means of atomic manipulation. They represent a two-site Kondo system with tunable interaction. Scanning tunneling spectroscopy reveals oscillations of the Kondo temperature T_K with the number n of Cu atoms for n>=3. Density functional calculations show that the Ruderman-Kittel-Kasuya-Yosida interaction mediated by the Cu chains causes the oscillations. Calculations find ferromagnetic and antiferromagnetic interaction for n=1 and 2, respectively. Both interactions lead to a decrease of T_K as experimentally observed.