The magnetic interactions in rare-earth metals and superlattices

The standard model of the rare-earth metals describes their properties in terms of localised 4f electronic moments interacting with one another through the conduction electrons and with the lattice through the crystal field. Detailed studies of the magnetic structures, particularly of Ho and Er, have shown that it is also necessary to include symmetry breaking trigonal interactions between the localised moments. Superlattices of some of the rare-earth metals have been shown to be coherent over many superlattice bi-layers, whereas for other systems the coherence is limited to single magnetic blocks. These results can be understood by an extension of the theory of interlayer coupling in the 3d transition metals when the long-range coherence is a consequence of the formation of a superlattice band structure. (C) 1999 Elsevier Science B.V. All rights reserved.