Synthesis, Structure And Property Of Giant Magnetostrictive TbDyFe Thin Films

Giant magnetostrictive films have drawn significant interest in recent years due to their multifunctional and potential uses in micro-sensors and micro-actuators.The TbDyFe films are deposited on Si(100)crystal substrate by DC magneton sputtering, and the sputtering technological processes of TbDyFe films is optimized in this paper. The microstructures,the magnetostrictive characteristics and the magnetic properties of TbDyFe films vacuum-annealed for different times at various temperatures are studied systematically.In order to lay a foundation of further application on the industry,the annealing technological processes on good magnetostrictive characteristics of TbDyFe films at the low magnetic field are studied.The results show that the magnetostrictive coefficient of the TbDyFe films increases at first,then decreases with the increase of Ar pressure.As the Ar pressure is 0.6 Pa,the magnetostrictive coefficient of the TbDyFe films reaches its maximum and the magnetostrictive characteristics of the TbDyFe films are optimal.The different distance of the substrate to the target affects the composition of the TbDyFe films and changes the structure,the magnetostrictive characteristics and the magnetic properties of the TbDyFe films.The Tb_0.28Dy_0.72Fe₂ and Tb_0.29Dy_0.71Fe_1.8films as deposited or vacuum-annealed at 450℃remain the amorphous structure.RFe₂ Laves phase is found in the Tb_0.28Dy_0.72Fe₂ and Tb_0.29Dy_0.71Fe_1.8films vacuum-annealed above 450℃.The growth of the grain size of laves RFe₂ phase accompanying with the appearance of the R₂O₃ in the Th_0.28Dy_0.72Fe₂ and Tb_0.29Dy_0.71Fe_1.8films are discovered with the increase of the annealing temperature.After vacuum-annealing,the easy magnetization direction of the Tb_0.28Dy_0.72Fe₂ films gradually turned from the perpendicular direction of the film plane to the parallel direction of the film plane.So the magnetostrictive properties of the Tb_0.28Dy_0.72Fe₂ films at the low magnetic field are improved by vacuum-annealing.The coercivity of the Tb_0.29Dy_0.71Fe_1.8films vacuum-annealed at 500℃and at 475℃for 30 min and 60 min is more than 1 kOe,so those Tb_0.29Dy_0.71Fe_1.8films are unfit for the application.The bee waist shape of the hysteresis loops in the Tb_0.29Dy_0.71Fe_1.8films vacuum-annealed at 475℃for 10 min is observed,and the bee waist shape of the hysteresis loops in the Tb_0.29Dy_0.71Fe_1.8films vacuum-annealed at 475℃for 30 min and 60 min gradually disappears.The magnetostrictive characteristics of the Tb_0.29Dy_0.71Fe_1.8films vacuum-annealed at 475℃for 10 min at the low magnetic field is comparatively well in the Tb_0.29Dy_0.71Fe_1.8films vacuum-annealed at 475℃for different times.The magnetostrictive characteristics of the Tb_0.29Dy_0.71Fe_1.8films vacuum-annealed at 450℃at the low magnetic field are better than those of the films vacuum-annealed at 475℃under the same vacuum-annealing time.The Tb_0.29Dy_0.71Fe_1.8films vacuum-annealed at 450℃for 60 min possess bigger in-plane saturation magnetization,smaller coercivity and larger magnetostriction at the low field in all the samples,so those films are fit for the application.