Nanoscale diffusion in Pt/56Fe/57Fe thin-film system

Abstract

Low-temperature diffusion of Fe in Pt/ 56 Fe/ 57 Fe thin films (grown on MgO (100) substrate) was investigated between 703 K and 813 K using secondary neutral mass spectrometry. The activation energy of the effective interdiffusion coefficients, evaluated by the -centre-gradient‖ method, is 1.53±0.25 eV reflecting a strong contribution from grain boundaries. This is also supported by the observed deep penetrations of Pt into the 56 Fe layer, from which the grain boundary diffusion coefficients for Pt in Fe were also estimated and 1.45±0.25 eV activation energy was obtained. A simple model, including the effect of grain boundaries to the overall intermixing at the original sharp interfaces in nanocrystalline films, is developed. This predicts that at short annealing times the grain boundary diffusion dominates, and bulk diffusion coefficients can be determined only in long time limit. At intermediate annealing times, when the grain boundaries are saturated but the bulk diffusion is still negligible, there are no changes in the composition profiles.This yields good qualitative agreement with the experimental data and offers explanation for the time and temperature dependence of the interdiffusion coefficients obtained in similar systems.

Low-temperature diffusion in thin-film Pt-(Au-)-Co heterostructures: a structural and magnetic characterization

“…The diffusion coefficients estimated in such a way after relatively low annealing temperatures correspond to atoms exchange or vacancy diffusion mechanisms at the interface region. We note that the applicability of this approach for the diffusion characterization in nanoscale stacks was proven for various systems, see for instance [49,50]. The estimated interface diffusion coefficients are summarized in table 3.…”