Effects of Rapid Cycle Annealing Temperature on TbFe Magnetostrictive Films

The effects of annealing temperature on TbFe films prepared by dc magnetron sputtering were discussed. X-ray diffraction patterns indicate that these polycrystalline films consisting mainly of α-Fe and TbFe₂ lave phase with grain sizes less than 25nm can be obtained by a rapid cycle annealing process. Grain sizes can be controlled by varying annealing temperatures. Film hysteresis loop studies show that annealing treatment can improve TbFe film in-plane soft magnetic performances. Magnetic domain structures explored by a magnetic force microscopy show that in the as-deposited films, maze domain structures exist, hence it possesses perpendicular anisotropy and larger anisotropic constant K_u. No domains are observed when annealing temperature is lower than 400°C. However, maze domain structures appear again when annealing temperature is higher than 400°C. Two maxima of magnetostrictive coefficients are obtained at annealing temperatures of 300°C and 500°C in the presence of a 40kA.m^-1 external magnetic field.