"Unusual magnetism in rare-earth ion systems with strong electronic correlations"

Savchenkov P. S. (NRC "Kurchatov Institute", Moscow, Russia)

The results of neutron research of the characteristic features of electronic states in systems of rare-earth ions with strong electronic correlations are discussed in the report.

It is shown how the effects of the crystal field, exchange interaction and hybridization between localized and band electrons, as well as their mutual competition lead to the implementation of "exotic" magnetic states: "induced" magnetism and the coexistence of a long-range magnetic order with strong spin fluctuations. In particular, features of magnetism are described in systems of rare-earth ions with a singlet ground state: EuCu₂Si­₂, PrNi, SmB₆. The development of theoretical and model concepts for interpreting the results obtained is presented.