We have grown high quality superlattices of Dy with nonmagnetic Lu and find that the 2.4% epitaxial compression nearly doubles the ferromagnetic ${\mathit{T}}_{\mathit{c}}$ of Dy with little change in the Néel temperature. A helimagnetic phase exists over a narrow temperature range. Below ${\mathit{T}}_{\mathit{c}}$ in superlattices, 300 Å 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.

• Received 27 August 1992

DOI:https://doi.org/10.1103/PhysRevLett.70.3502