Rare earth elements and magnetism in metallic systems

A theoretical review of roles of rare earth elements in determining magnetic properties of metallic materials is presented. Starting with the problem of the formation of a magnetic moment in the 4f state in a solid, the discussion covers the interaction between magnetic moments, the Kondo effect and related problems. Subsequently the interaction between rare earth and transition elements and the role of interstitial typical elements in ferromagnetic intermetallic compounds are discussed on the basis of electronic structure calculations.