Strain in single-crystal RFe2(110) thin films (R = Y, Sm, Gd, Tb, Dy0.7Tb0.3, Dy, Er, Lu)

Single-crystalline RFe2(110) compounds (R = Y, Sm, Gd, Tb, Dy0.7Tb0.3, py, Fr, and Lu) have been grown by molecular-beam epitaxy. Compared to the bulk compounds, the chin films exhibit modifications of the magnetic anisotropy , related tb the strains induced during deposition. We present here a detai led determination of in-plane and out-of-plane parameters using x-ray and n eutron diffraction. RFe2 films and RFe2 /YFe2 bilayers have been deposited on a Nb buffer covered with Fe. Both systems are strained compared to bulk compounds: they are expanded in the plane of epitaxy and compressed along t he growth direction. For single RFe2 films, the strains do not depend, on t he lattice parameters of the corresponding bulk compounds, i.e., on the lar ge mismatch between the film and the buffer (around 10%). The sign and the values of the strains are explained with a model of differential thermal co ntraction between the film and the substrate. For RFe2 films involved in RF e2/YFe2 bilayers, the mismatch between RFe2, and the YFe2, layer is smaller and the strains in the RFe2 films do depend on the bulk lattice parameters . Their evolution can be explained with an elastic model. [S0163-1829(99)00 107-1].