Critical Thickness of (001) Texture Induction in FePt Thin Films on Glass Substrates

Development of (001) texture in FePt thin films deposited on glass substrates with different thickness (t) treated by rapid thermal annealing (RTA) is studied. A critical thickness of 30 nm is characterized: below which the (001) preferred orientation of the films develops with increasing t ; when t >; 30 , the films become isotropic. Remarkable perpendicular anisotropy in magnetic properties is achieved in the 30 nm thick sample with the best (001) texture. Discontinuous changes are also observed in surface morphology, microstructure, magnetic domain structure, and internal stress. Direct evidences are presented relating the formation of (001) texture to abnormal grain growth. The internal stress/strain analysis indicates that the residual tensile (σ) stress is proportional to the degree of (001) preferred orientation. A large value of σ of about 8.9 GPa is obtained in the film with t = 30, suggesting the driving force forming the texture.