NEUTRON-SCATTERING ON RARE-EARTH INTERMEDIATE VALENCE SYSTEMS

A survey on neutron scattering experiments performed on rare earth compounds and alloys with intermediate valency (IV-systems) is given. The dynamical susceptibility of these systems as deduced from inelastic magnetic neutron scattering experiments is characterized by a very broad, structureless and nearly temperature independent energy spectrum which can be interpreted by a fast (10-13 s) relaxation process of the IV-spins. This simple behaviour is observed for all IV-systems with one magnetic and one nonmagnetic configuration (e.g., CePd3). The only IV-system with two magnetic configurations (TmSe) behaves similarly at temperatures above 120 K; at lower temperatures, however, the spin fluctuations slow down with decreasing temperature and an additional inelastic magnetic transition develops around 10 meV energy transfer. At the end of our survey, we will discuss the influence of the IV-phenomenon on the magnetic formfactor, atomic excitations and phonon spectra. © 1979.