MAGNETIC CLUSTER EXCITATIONS

Abstract

Magnetic cluster systems can be considered as nanomagnets consisting of a small number of interacting spins that are magnetically isolated from the neighboring clusters of the compound by nonmagnetic ligands. Inelastic neutron scattering is a powerful experimental tool for the study of magnetic clusters, since it provides direct access to energy splittings. The present work provides an overview on this subject. The underlying concepts are presented and illustrated for some representative examples such as single-molecule magnets, diluted magnets, magnetic polarons, and dimer based compounds associated with quantum phase transitions and Bose–Einstein condensation as well as spin-Peierls dimerization. It is shown that — besides the dominant Heisenberg interaction — anisotropic and higher-order exchange terms are often needed to rationalize the experimental data.