Exchange coupling in [Dy‖Er] metallic superlattices

Abstract

Magnetic exchange coupling in metallic superlattices of [Dy‖Er], grown by molecular-beam epitaxy, has been examined by neutron diffraction. In a superlattice of 65-Å layers of Dy and 55-Å layers of Er, distinct ordering temperatures were observed for the Dy and Er layers. Basal plane helical ordering of the Dy layers was initiated at temperatures close to TN for bulk Dy (178 K) with a long-range interaction, preserving both phase and chirality, mediated through the Er layers. At a temperature near 70 K, the helical coupling of the Dy spins is replaced by an antiferromagnetic coupling of adjacent ferromagnetically ordered Dy layers coexisting with a remanent helical order. At a temperature well below TN of bulk Er, c-axis ordering of the Er spins occurs in the superlattice, and in measurements at 10 K there is evidence of basal plane moment ordering in the Er.