Ultrathin two-dimensional gold films have been grown on an amorphous Ge underlayer by quench condensation at low temperature, followed by adsorption of magnetic Gd atoms and nonmagnetic Y atoms. The resulting electrical transport as a function of temperature and composition has been investigated in situ. Gold films of different sheet resistances $\left(R_{◻}\right)$ have been used for the Gd and Y adsorption platform. The temperature and thickness dependence of the conductance $G$ $\left(G=1/R_{◻}\right)$ indicates that the Au films cross from a strongly localized regime, where conductivity is through hopping and where electron correlation effects are expected to be strong, to a weakly localized regime. The system is shown to be sensitive to different added electronic states, in that adding Gd or Y increases $G$, but much less than adding the same amount of Au for all initial $G$ values. No difference is observed (down to 5 K) between added Gd and Y, showing that there is no effect of the Gd magnetic moments on electrical transport. The absence of magnetic localization and dominance of adding electronic states over added electronic potential disorder in this quench-condensed ultrathin system is discussed and attributed to the intrinsically high electronic concentration of Au.

• Received 27 January 2010

DOI:https://doi.org/10.1103/PhysRevB.82.195447