Magnetic structure in Dy/Sc superlattices

We have investigated magnetic order in superlattices of Dy and Sc grown along the hcp c axis by molecular beam epitaxy (MBE) techniques. Our neutron diffraction experiments reveal that individual Dy layers order ferromagnetically below Tc∼150 K. The magnetic coherence length along the growth direction is less than the Dy-layer thickness. Previous studies of rare-earth superlattices with Y or Lu as spacer layers have shown that magnetic coherence propagates through sufficiently thin nonmagnetic interlayers. This arises from the long-range exchange interaction that originates from nesting features in the Fermi surface of the spacer material. The lack of coupling in Dy/Sc superlattices reflects the very different Fermi surface of Sc, with much weaker nesting than Y and Lu.