Effects of heteroepitaxial strain on Laves phases TbFe2 and DyFe2

(110) oriented growth was observed for thin films of the highly magnetostri ctive Laves phases TbFe2 and DyFe2 on Ta (110). On Nb (111), TbFe2 nucleate s in the (111) orientation. Depending on the substrate temperature during g rowth, varying degrees of residual tensile strain were observed in the film s. For TbFe2 grown on Ta (110) at 680 degrees C, x-ray diffraction revealed a splitting of the (220) Bragg reflection into a strain free component str ucturally coherent with the template, and a component with 0.5% biaxial ten sile strain at room temperature. This strained component can be attributed to the difference in thermal expansion between the sapphire substrate and t he TbFe2 film. Magnetic hysteresis measurements revealed that the axis of e asy magnetization lies in the film plane for both (110) and (111) oriented samples. (C) 1998 American Institute of Physics. [S0021-8979(98)25411-9].