Neutron-Scattering Measurements of the Generalized Susceptibilityχ(q,E)for Ni

Neutron-scattering measurements have been performed on nickel to obtain more information about $\chi \mathrm{}(q,E)\mathrm{}$,the generalized susceptibility. Evidence of an optical mode that crosses the main [100] spin-wave branch was found in agreement with predictions based on the intinerant-electron band-theory approach. No optical mode was found for the [111] direction; however, the dispersion curve is found to deviate from a quadratic dispersion law.