Quantum modulation of the Kondo resonance of Co adatoms on Cu/Co/Cu(100):: Low-temperature scanning tunneling spectroscopy study

Low-temperature scanning tunneling spectroscopy reveals that the Kondo temperature T-K of Co atoms adsorbed on Cu/Co/Cu(100) multilayers varies between 60 and 134 K as the Cu film thickness decreases from 20 to 5 atomic layers. The observed change of T-K is attributed to a variation of the density of states at the Fermi level rho(F) induced by quantum well states confined to the Cu film. A model calculation based on the quantum oscillations of rho(F) at the belly and the neck of the Cu Fermi surface reproduces most of the features in the measured variation of T-K.