A quasielastic neutron scattering study has been performed on UCu > Al \ , a system which reveals an alloying-induced transition from magnetic order to heavy-fermion behavior. The magnetic response can be described by a broad quasielastic Lorentzian for all concentrations. No crystal field excitations could be detected. Remarkably, the linewidth decreases with increasing hybridization strength and seems to be no measure of the Kondo lattice temperature T*. In addition, electron spin resonance (ESR) experiments were performed which revealed that, even in the heavy-fermion regime, spin fluctuations play an important role. Both experimental findings are in distinct contrast to cerium-based heavy fermion systems.

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Gd EPR measurements on the heavy-fermion system are reported. In agreement with NMR results, we observe a heavy-fermion behaviour for and the opening of a spin gap below . Our data reveal an almost constant dynamical susceptibility for , followed by a Curie - Weiss-like decrease for higher temperatures. The temperature dependence of the magnetic relaxation rate is calculated and compared with that derived from neutron scattering experiments.

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