ANNEALING EFFECTS ON THE PHYSICAL-PROPERTIES OF UAU2SI2

We have investigated the effects of annealing on the uranium intermeta llic compound UAu2Si2. The physical properties of both the annealed an d as-cast samples were studied from 5 to 300 K. Both the resistivity r ho(T) and low-field magnetic susceptibility chi(T) of the as-cast samp le show anomalies at 18 K and at 82 K; whereas the heat capacity C(T) shows only an anomaly at 20.5 K. The rho(T) and chi(T) of the annealed sample displays a low-temperature anomaly around 20 K; and a complex magnetic phase transition between 48 K and 55 K was observed. A sharp anomaly of C(T) in the annealed UAu2Si2 can be seen at 21.5 K. The ann ealed sample shows Fermi-liquid behavior below 10 K with a coefficient of the quadratic term in the temperature dependence of the resistivit y being 11.5 mu Omega-cm K-2. The low temperature electronic coefficie nt gamma of the annealed sample is 92 mJ mol K-2. UAu2Si2 has heavy-fe rmion behavior with ferromagnetic ground state, which is an uncommon b ehavior in the uranium intermetallic compounds. (C) 1997 Elsevier Scie nce Ltd.