Possible heavy-fermion behaviour of new U(Cu, Al)5 compounds

Abstract We have synthesized several new UCu x Al 5 − x compounds in the composition range between x = 2.9 and x = 3.5, which were found to form in crystal structures related to the CaCu 5 structure. Specific-heat measurements reveal a considerable enhancement of the low-temperature specific-heat coefficient γ for all U(Cu, Al) 5 compounds investigated, with a maximum value of 450 mJ/molK 2 at 1.2 K for UCu 2.9 Al 2.1 .