Effect of annealing temperature on microstructure and magnetism of FePt/TaOx bilayer

Abstract

The effect of annealing temperatures on the microstructures and magnetism of FePt/TaOx bilayers wassystemically investigated in the range of 25–650 C. Microstructural characterization reveals that higherannealing temperatures lead to higher ordering parameters and larger grain sizes. High order parameterup to 0.57 was acquired after the sample was annealed at 600 C. Diffusion was observed from TaOx layerinto FePt layer after annealing at temperature over 550 C. The out-of-plane coercivity first increased andexhibited a maximum value up of 4.2 kOe after annealing at 550 C and decreased as the annealing temperaturewas further increased. The coercivity increase with higher annealing temperature was attributedto the rise of magnetocrystalline anisotropy due to the formation of the ordered fct FePt structures