MAGNETIC-STRUCTURE IN DY SC SUPERLATTICES

We have investigated magnetic order in superlattices of Dy and Sc grow n along the hcp c axis by molecular beam epitaxy (MBE) techniques. Our neutron diffraction experiments reveal that individual Dy layers orde r ferromagnetically below T(c) approximately 150 K. The magnetic coher ence length along the growth direction is less than the Dy-layer thick ness. Previous studies of rare-earth superlattices with Y or Lu as spa cer layers have shown that magnetic coherence propagates through suffi ciently thin nonmagnetic interlayers. This arises from the long-range exchange interaction that originates from nesting features in the Ferm i surface of the spacer material. The lack of coupling in Dy/Sc superl attices reflects the very different Fermi surface of Sc, with much wea ker nesting than Y and Lu.