Investigation of hard magnetic properties in the Fe-Pt system by combinatorial deposition of thin film multilayer libraries

The magnetic properties of annealed Fe-Pt multilayer thin films with a broad composition range were investigated in order to identify the effects of composition and annealing temperature on the achievable coercive field, and to identify its maximum at low processing temperatures. Two types of multilayer systems were deposited as materials libraries to vary the composition from Fe₂₀Pt₈₀ to Fe₇₅Pt₂₅. The first type of multilayer was comprised of alternating opposing wedges, whereas the second type consisted of repeated uniform Fe and Pt layers interspersed periodically with Fe wedge layers. It was found that coercive fields μ₀H_C > 0.7 T can be achieved at an annealing temperature of about 300 °C (60 min) for both types of multilayers as long as the composition is close to 50:50. Higher annealing temperatures are needed for films, which deviate from this composition. Increasing the annealing temperature up to 700 °C leads to increased coercivity values. Multilayers with additional Fe layers showed increased remanence but reduced coercive fields.