Specific heat measurements on U-2(Ru1-xRhx)(3)Si-5 ternary silicides

Specific heat (C) measurements have been performed on several compositions of the U-2(Ru1-xRhx)(3)Si-5 system showing an interesting magnetic phase diagram: (i) no magnetic ordering appears above 2 K for 0 less than or equal to x<0.25; (ii) on the contrary, two antiferromagnetic ranges exist, respectively, for 0.25 less than or equal to x less than or equal to 0.50 and 0.50antiferromagnetic transition), a very strong enhancement of CIT is observed below 12 K, reaching a value as high as 255 mJ/U-mol K-2 at 2 K. This behaviour suggests either the occurrence of magnetic ordering below 2 K or that this silicide can be considered as the heaviest electron system. (C) 1998 Elsevier Science S.A.