Magnetic excitations in crystal-field split 4f systems

Abstract

A survey is given of magnetic excitations in metallic 4f systems when the crystal-field splitting is comparable to or larger than the magnetic interaction between different sites. Particular emphasis is put on the interaction of crystal-field split rare-earth ions with conduction electrons. A number of physical effects is discussed which result from that interaction. The modifications of the magnetic excitations are described which result when the coupling of phonons to the crystal-field levels is so strong that a bound state between the two types of excitations is formed. For a study of these phenomena the method of neutron scattering is an indispensable tool. For that reason it plays a central part in this review. © Taylor & Francis Group, LLC.