text: The overall metallic behavior of UPdAl, e.g. as deduced from the dc resistivity, is typical for a heavy-fermion material and can be explained as follows: incoherent Kondo scattering above approximately 80 K and coherent heavy-fermion state (in a Kondo lattice) at lower temperatures. Upon cooling below 14 K, UPdAl orders antiferromagnetically in a commensurate fashion (ordering wave vector (0,0,1/2)) and with a sizable ordered magnetic moment of approximately 0.85 µ per uranium atom, as determined from neutron scattering.
  The metallic heavy-fermion state is characterized by a strongly enhanced effective mass, which is connected to a reduced Fermi velocity, which in turn brings about a strongly suppressed transport scattering rate. Indeed, for UPdAl optical Drude behavior with an extremely low scattering rate was observed at microwave frequencies. This is the slowest Drude relaxation observed for any three-dimensional metallic system so far.