Interdiffusion in Ni80Fe20/Mo magnetic multilayers prepared by magnetron sputtering

Abstract

The interdiffusion in Ni80Fe20/Mo magnetic multilayers with a repeat length of 3.4 nm has been investigated using x-ray diffraction (XRD) technology. The multilayers have been fabricated by using a magnetron sputtering system. The decay with annealing time in the intensity of the first-order x-ray satellite peak arising from the composition modulation was used to determine the effective interdiffusion coefficient Dλ. As the annealing temperature is below 483 K, the interdiffusion is found to be relatively slow (Dλ < 8.88 × 10−25 m2/s). This result suggests that the Ni80Fe20/Mo multilayers have a strong resistance to the atomic interdiffusion between sublayers. The diffusivities over the temperature range 343–683 K have an Arrhenius-type temperature dependence with a pre-exponential factor D0 = (4.02 ± 1.21) × 10−22 m2/s and an activation enthalpy of about 0.26 ± 0.08 eV. The much lower activation enthalpy is attributed to the coherence strains existing in the multilayers.