Magnetostriction in polycrystalline sputter-deposited TbDyFe films

Magnetic and microstructural investigations of some polycrystalline rare-earth—transition-metal (RE-TM) alloy thin films are reported. Emphasis was placed on pseudobinary alloys in the (TbxDy1−x)Fe2 and (TbxDy1−x)3Fe4 systems. The films were prepared by sputter deposition onto both room-temperature and high-temperature substrates. Films prepared on room-temperature substrates were amorphous and were crystallized by postdeposition annealing. Transmission electron microscopy and x-ray diffraction showed and indicated a complex microstructure consisting of small grains of free iron, REFe compounds, and some RE oxide phases. Magnetization, coercivity, and magnetostriction measurements showed the films to be essentially magnetized in plane with a trend across the composition range which reflected the different influences of Tb and Dy and also the compensation condition. Magnetostriction values greater than 0.75×10−3 were found near the Terfenol composition Tb0.27Dy0.73Fe2 and for x≳0.3.