Magnetoelastic and Exchange Contributions to the Helical-Ferromagnetic Transition in Dysprosium Epitaxial Films

The Curie temperature of dysprosium films epitaxially grown on yttrium and on erbium is shown to increase continuously with the epitaxial strain induced along the c -axis. This variation is correlated to modifications of the α strains, of the γ distortion and of the exchange energy barrier. The evolution of these different terms is discussed from the experimental thermal variations of the lattice parameters and turn angles determined by neutron diffraction.