Evolution of structural and magnetic properties in Ta/Ni ₈₁Fe₁₉ multilayer thin films

Abstract

The interdiffusion kinetics in short period (12.8 nm) Ta/Ni 81Fe19 polycrystalline multilayer films has been investigated and related to the evolution of soft magnetic properties upon thermal annealing in the temperature range 300-600°C. Small angle x-ray diffraction and transmission electron microscopy were used to estimate the multilayer period. Interdiffusion in the multilayers was directly computed from the decay of the satellites near (000) in a small angle x-ray diffraction spectrum. A kinetic analysis of interdiffusion suggests that grain growth is concurrent with grain boundary diffusion of Ta in Ni81Fe 19. The evolution of soft magnetic properties of Ni 81Fe19, i.e., lowering of 4πMs and increase in coercivity Hc, also lend support to the above analysis.