EXCHANGE COUPLING IN [DY-VERTICAL-BAR-ER] METALLIC SUPERLATTICES

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-angstrom layers of Dy and 55-angstrom layers o f Er, distinct ordering temperatures were observed for the Dy and Er l ayers. Basal plane helical ordering of the Dy layers was initiated at temperatures close to T(N) for bulk Dy (178 K) with a long-range inter action, preserving both phase and chirality, mediated through the Er l ayers. At a temperature near 70 K, the helical coupling of the Dy spin s is replaced by an antiferromagnetic coupling of adjacent ferromagnet ically ordered Dy layers coexisting with a remanent helical order. At a temperature well below T(N) of bulk Er, c-axis ordering of the Er sp ins occurs in the superlattice, and in measurements at 10 K there is e vidence of basal plane moment ordering in the Er.