Influence of substrate temperature driven magnetic anisotropy on the magnetostrictive behavior of TbFeCo thin films

TbFeCo thin films were grown at different substrate temperatures on Si 〈1 0 0〉 substrates to engineer their structure, microstructure, magnetic anisotropy and magnetostriction. Structural studies showed an amorphous structure for the as-deposited film. However, films deposited at higher substrate temperatures exhibited formation of Tb2(Fe,Co)17 and FeCo phases. Magnetization studies displayed presence of in-plane magnetic anisotropy for all the films. In addition to this, strong out-of-plane magnetic anisotropy co-existing with in-plane component has been observed for the film grown at 400 °C. These observations were further confirmed by the magnetic microscopy studies which showed strong magnetic phase contrast for the film processed at 400 °C. Consequently, the magnetostriction calculated from tip deflection measurements was found to be very small for this film. A maximum magnetostriction of about 300 ppm has been realized for the film grown at 550 °C owing to the presence of in-plane magnetic anisotropy, enhancement in crystallization and relaxation of stresses.