Magnetic properties of the UNi1-xPtxGa solid solutions

The results of a structure and magnetization study of the UNi1-xPtxGa pseudoternary compounds are presented. Only limited solubility ranges 0less than or equal toxless than or equal to0.15 and 0.8less than or equal toxless than or equal tol have been observed. The solid solutions preserve the ZrNiAl-type structure of the parent ternary compounds. The magnetization as a function of temperature and magnetic field indicates that the antiferromagnetic ground state of UNiGa is converted to ferromagnetism by only slight doping by Pt. On the other hand, the ferromagnetism in UPtGa seems to be nearly intact following the substitutions in the transition metal sublattice of up to 20% Ni. These results confirm that the antiferromagnetic ground state of UNiGa is a result of a delicate balance between antiferromagnetic and ferromagnetic components of exchange interactions mediated by the 5f-ligand hybridization. This state is very fragile with respect to application of magnetic field and substitution of Ni by other transition metals. (C) 2002 Elsevier Science B.V. All rights reserved.