Local magnetism of isolated Mo atoms at substitutional and interstitial sites in Yb metal: Experiment and theory

We have observed large 4d moments on isolated Mo atoms at substitutional an d octahedral interstitial lattice sites in Yb metal, showing Curie-Weiss lo cal susceptibility and a Korringa-like spin relaxation rate. The interstiti al Mo atoms, despite strong hybridization with the Yb neighbors, show rathe r small Kondo temperature (T-K less than or equal to 60 K), implying high m oment stability. While magnetism of Mo at the substitutional site is consis tent with Kondo-type d-sp interaction, we suggest that moment stability at the interstitial site is strongly influenced by ferromagnetic polarization of Yb-4f5d band electrons.