Superconductivity and spin-glass regime in amorphous La80Au20 alloys doped with Gd

Magnetization and resistivity measurements are performed on amorphous La₈₀Au₂₀ alloys doped with Gd impurities. The anomalous behavior observed in the dependence of the superconducting transition temperature on Gd concentration is related to the onset of spin-spin correlations among the Gd impurities. This study suggests the co- existence of superconductivity and spin-glass regime in several previously investigated superconductors doped with Gd.