Excitonic Mass Enhancement in Praseodymium

Abstract

The crystal field experienced by the Pr ions in praseodymium metal produces singlet ionic ground states. The conduction electrons provide an indirect exchange coupling between the Pr ions which is not strong enough to produce long-range order but which does give rise to magnetic excitons. It is shown that these excitons contribute to the effective mass of the conduction electrons, an effect which is large and magnetic-field dependent.