Thermopower study of La- and Ce-doped URu2Si2

We have measured the thermopower of La-and Ce-doped URu2Si2. Since a feature distinctively related to an antiferromagnetic transition in URu2Si2 disappears between 2% and 5% of doping, we conclude that a small amount of either La- or Ce-doping modifies the magnetic ground state of URu2Si2 significantly. At higher concentrations, however, the thermopower data of La-and Ce-doped URu2Si2 differ from each other. This suggests that although U moments in (U,La)Ru2Si2 possibly become localised with increasing La concentration (U,Ce)Ru2Si2 seems to remain strongly hybridised up to 40% of Ce. (orig.)