Atomic interdiffusion in Pt-Ni thin films at low temperatures: An in-situ X-ray reflectivity study

Abstract

We have investigated the kinetic process of the atomic interdiffusion across the interface in thin platinum‑nickel (Pt-Ni) bilayer films at temperatures ranging from 230 °C to 300 °C by in-situ X-ray reflectivity (XRR). The Pt-Ni interface width obtained by analyzing the XRR curve provides the time evolution of the diffusion length in nanometer scale and the diffusivity of atoms across the interface. We find that the interdiffusion is dominated by Ni atoms with an associated activation energy Q of 0.87 ± 0.05 eV. The analysis of the anomalous XRR measured with various X-ray energies across the K absorption edge of Ni provides more accurate electron density profile near the interface.