SPECIFIC-HEAT OF UPD2AU3 - EVIDENCE FOR AN UNUSUAL HEAVY-FERMION STATE

Low-temperature specific heat and magnetic susceptibility are reported for UPd5-xAux alloys, for 2.5 < x < 3.2 and x = 1. Theses low-tempera ture properties reflect a competition between ferromagnetic and antife rromagnetic interactions between U moments. UPd2Au3 orders antiferroma gnetically at 3 K. Between 4 and at least 14 K, its C/T is proportiona l to T-2 with a large value of the C/T intercept gamma(H) of about 670 mJ/K-2 and a slope 3 mJ/K-4 mol. Below T-N, its specific heat has a m agnon-derived T-3 term and a linear term (gamma(L)T), gamma(L) = 500 m J/K-2 mol. Both values of gamma(L) and gamma(H) place this alloy into a heavy-fermion category.