Kondo effect of single Co atoms adsorbed on Pb/Si(111) nanoislands

Abstract

Using scanning tunneling spectroscopy, we have investigated the local electronic property change upon single Co atom adsorption on Pb nanoislands and/or films grown on a $\text{Si}(111)\text{\ensuremath{-}}7\ifmmode\times\else\texttimes\fi{}7$ surface. The quantum well states formed on the clean Pb film were found to be locally destroyed by the adsorbed single Co atom. Moreover, the differential conductance $dI/dV$ curves, exhibiting an asymmetric line shape with a dip and a hump, respectively, below and above the Fermi level, demonstrated a Kondo effect from the adsorbed Co atom on the Pb film. The similar line shapes of the $dI/dV$ spectra and the similar Kondo temperatures for Co atoms adsorbed on Pb island areas of different Pb thicknesses further showed that the different densities of states at the Fermi level originated from the quantum well states do not play a significant role, possibly due to the destruction of the quantum well states upon the Co atom adsorption.