SPIN FLUCTUATIONS IN THE HEAVY-FERMION SUPERCONDUCTOR UPD2AL3 STUDIEDBY NEUTRON INELASTIC-SCATTERING

We have found that there are two contributions to the dynamical respon se in UPd2Al3. The first is a heavily damped spin-wave: which has been observed previously. It shows no appreciable change on warming throug h T-c, but softens and becomes overdamped as T approaches T-N. The sec ond is a quasielastic-like component that exists in the antiferromagne tically ordered state and is strongly localized around the ordered wav evector. As a function of temperature this component exhibits a minimu m at the superconducting transition temperature T-c, and increases str ongly below T-c. Its width in the momentum space at T = 0.5 K correspo nds to a correlation length of similar to 50 Angstrom, which is close to the superconducting coherence length of similar to 85 Angstrom.