Enhanced Curie temperatures and magnetoelastic domains in Dy/Lu superlattices and films

We have grown high quality superlattices of Dy with nonmagnetic Lu and find that the 2.4% epitaxial compression nearly doubles the ferromagnetic Tc of Dy with little change in the N\'eel temperature. A helimagnetic phase exists over a narrow temperature range. Below Tc in superlattices, 300 {} orthorhombic domains form despite epitaxial constraints, each with a magnetostrictive distortion comparable to that of bulk Dy. For the thinnest intervening Lu layers, individual ferromagnetic Dy blocks have parallel alignment; the remaining samples show antiparallel alignment, coherent over many bilayer periods.