MAGNETIC EXCITATIONS AND THE SEARCH FOR CRYSTAL-FIELD TRANSITIONS IN THE HEAVY-FERMION SUPERCONDUCTOR UPD2AL3

We have performed inelastic neutron scattering (INS) experiments to st udy the spin dynamics and search for crystalline-electric-field (CEF) excitations in the antiferromagnetic heavy-fermion superconductor UPd2 Al3. The low-energy-transfer spectra are predominantly characterized b y a quasielastic Lorentzian (weighted by the detailed balance factor) with a residual line width of approximately 5 meV. For uranium-based i ntermetallics, this is an unusually small line width and UPd2Al3 is on e of the rare examples of 5f-electron systems whose residual line widt h corresponds to the macroscopically estimated Kondo lattice temperatu re. However, significant deviations from this fit suggest additional i nelastic contributions that persist up to T = 150 K, i.e. 10T(N). This additional scattering may be attributed to the presence of CEF excita tions or intersite magnetic correlations. A survey of the scattering w ithin the whole accessible momentum-energy space provides further evid ence for the existence of these inelastic magnetic intensities. We fin d a surprisingly good agreement between the excitation energies of our neutron scattering spectra and a CEF-level scheme proposed on the bas is of magnetic susceptibility and specific heat measurements.