THE MAGNETIC-PROPERTIES OF ER LU SUPERLATTICES/

Superlattices of erbium and lutetium were grown by molecular beam epit axy (MBE) and were examined using x-ray and neutron scattering techniq ues. When cooled below a temperature of about 86 K, the superlattices develop a coherent longitudinal modulated magnetic structure similar t o that found in bulk Er. The structures are coherent over approximatel y 600 Angstrom, or several superlattice block lengths. When cooled bel ow 65 K, the Er moments also order in the basal plane and form a cyclo idal structure for which the coherence length decreases to about 200 A ngstrom. At low temperatures, below 20 K, the cone structure of bulk E r is suppressed and the structure of the Er blocks in the superlattice is a commensurate, q = 1/4c, cycloid. These results are compared wit h 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 superlatti ces.