The effect of residual strain on (001) texture evolution in FePt thin film during postannealing

Abstract

Residual strain in a Fe55Pt45 thin film was investigated in order to provide experimental support for a previous theoretical study [J.-S. Kim et al., J. Appl. Phys. 99, 053906 (2006)] in which a strong evolution of (001) texture during the postannealing of deposited FePt thin films was attributed to amorphous substrates. Residual strain measurements using dual diffraction peaks to analyze the strain state were used in the study. The findings show that transformation and biaxial in-plane strains coexist in annealed Fe55Pt45 films and their effect could lower the strain energy of the (001) crystal (crystal with a [001] crystallographic orientation into the surface normal) when grain growth proceeds actively. Therefore, we propose that anisotropic strain due to ordering transformations under tensile in-plane strain is a key factor that affects texture evolution. The importance of the subsequent grain growth is also discussed.