Preparation and Characterization of Ultrathin Stainless Steel Films

We report on the preparation of polycrystalline austenitic 310 ((Fe0.55Cr0.25Ni0.20)-Fe-57) stainless steel (SS) thin films on Si substrates and the characterization of their residual magnetism via Fe-57 conversion-electron Mossbauer spectroscopy (CEMS). The films were structurally characterized at room temperature by X-ray diffraction (XRD). The virgin films were found to be structurally disordered. Subsequent annealing at moderate temperatures in ultrahigh vacuum produces the ordered martensitic and austenitic SS phases. Further annealing at higher temperatures (up to temperatures where long-range diffusion into the substrate is still weak) transforms the films into the austenitic phase with no trace of a magnetic hyperfine interaction. However, when a 2 nm thick SS thin film is embedded between two carbon layers, the as prepared disordered SS film does not transform to the martensitic or austenitic SS phase irrespective of the annealing temperature, probably because the interdiffusion with C prohibits the formation of these phases.