The magnetic properties of Er/Lu superlattices

Abstract

Superlattices of erbium and lutetium were grown by molecular beam epitaxy (MBE) and were examined using x-ray and neutron scattering techniques. When cooled below a temperature of about 86 K, the superlattices develop a coherent longitudinal modulated magnetic structure similar to that found in bulk Er. The structures are coherent over approximately 600 Å, or several superlattice block lengths. When cooled below 65 K, the Er moments also order in the basal plane and form a cycloidal structure for which the coherence length decreases to about 200 Å. At low temperatures, below 20 K, the cone structure of bulk Er is suppressed and the structure of the Er blocks in the superlattice is a commensurate, , cycloid. These results are compared with those obtained for bulk Er and for Er/Y superlattices for which the basal-plane strain is of the opposite sign to that of Er/Lu superlattices.