MAGNETIC-PROPERTIES OF THE UCO1-XPTXAL SOLID-SOLUTIONS

In framework of systematic study of the 5f-band metamagnet UCoAl, we r eport on magnetic properties of quasiternary UCo1-xPtxAl compounds. Al though UPtAl is a ferromagnet, the initial substitutions of Pt for Co (x less than or equal to 0.05) cause gradual suppression of the ''UCoA l-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 cri tical Pt concentration for the onset of ferromagnetism is 0.2<x(c)<0.3 ). Both the uranium magnetic moment and the Curie temperature monotono usly increase with further increasing Pt content. Evolution of magneti sm in UCo1-xPtxAl series is discussed in the context of other quasiter nary UCo1-xTxAl systems (T=Fe, Ni, Ru) studied so far. (C) 1998 Elsevi er Science S.A.