Direct observation of spin fluctuations in the heavy-fermion systemUPt3

Abstract
Spin-polarized neutron scattering data for the heavy-fermion superconductor UPt3 are presented. The form factor characterizing the measured spin fluctuations is similar to that for insulating uranium compounds. At low temperatures, the energy scale for the fluctuations is ≊10 meV, while the spin-flip scattering cross section, measured for energy transfers below 48 meV and expressed in absolute units, is in agreement with bulk susceptibility data.