Magnetic properties of the UCo1-xPtxAl solid solutions

In framework of systematic study of the 5f-band metamagnet UCoAl, we report on magnetic properties of quasiternary UCo1-xPtxAl compounds. Although UPtAl is a ferromagnet, the initial substitutions of Pt for Co (x less than or equal to 0.05) cause gradual suppression of the "UCoAl-type" metamagnetism. Compounds with 0.05<x less than or equal to 0.20 are paramagnetic without any sign of metamagnetism in fields up to 5 T. UCo0.7Pt0.3Al exhibits ferromagnetic ordering below 8 K, (the critical Pt concentration for the onset of ferromagnetism is 0.2<x(c)<0.3). Both the uranium magnetic moment and the Curie temperature monotonously increase with further increasing Pt content. Evolution of magnetism in UCo1-xPtxAl series is discussed in the context of other quasiternary UCo1-xTxAl systems (T=Fe, Ni, Ru) studied so far. (C) 1998 Elsevier Science S.A.