Kondo effect of single Co adatoms on Cu surfaces

The Kondo resonance of Co adatoms on the Cu(100) and Cu(111) surfaces was studied by scanning tunneling spectroscopy. The scaling of the Kondo temperature with the host electron density at the magnetic impurity was demonstrated. The tunneling spectra revealed that Kondo resonance was dominated by Cu bulk electrons. It was found that at Cu(100) surface both tunneling into the hybridized localized state and into the substrate conduction band contributed to the Kondo resonance and the latter channel was dominant for Cu(111).