Spin-current induced Kondo-resonance splitting of a single cobalt atom

TL;DR

This study demonstrates that spin currents can induce splitting of the Kondo resonance in a single cobalt atom, revealing the interplay between spin transport and many-body quantum effects at the atomic scale.

Contribution

It provides experimental evidence of spin-current induced Kondo-resonance splitting using a low-temperature STM with a nickel tip and Co atom, highlighting the role of spin polarization.

Findings

Kondo resonance splits upon contact with spin-polarized tip

Spin polarization of the junction reaches up to 18%

Splitting decreases with direct contact to pristine nickel tip

Abstract

We use a low-temperature scanning tunneling microscope to study the interplay between the Kondo effect of a single-atom contact and a spin current. To this end, a nickel tip is coated by a thick layer of copper and brought into contact with a single Co atom adsorbed on a Cu(100) surface. We show that upon contact the Kondo resonance of Co is spin split and attribute the splitting to the spin current produced by the nickel tip and flowing across the copper spacer. A quantitative line shape analysis indicates that the spin polarization of the junction amounts up to 18%, but decreases when a pristine nickel tip is directly contacted to the Co atom.