Stratification in Thin Permalloy Films

Permalloy films have been studied to determine composition variations which exist in a direction normal to the substrate surface. These films are formed by a noninterrupted deposition process. They are classified according to the amount of oxygen present on the substrate prior to deposition. If normal care is taken to produce a clean glass substrate, a thin layer of αFe2O3 and NiFe2O4 is produced at the film-substrate interface. Those films produced on a substrate saturated with oxygen have a thick negative magnetostrictive alloy layer adjacent to the substrate. This nickel-rich alloy presumably results from the diffusion of oxygen through the depositing films and the formation of iron oxide and nickel ferrite. In addition to the chemical analysis of the films, evidence to support the idea of stratification is found in the etch experiments, resonance data, saturation magnetization measurements, and cross section analysis.