Lowering of ordering temperature for fct Fe–Pt in Fe/Pt multilayers

Abstract

We have explored magnetic properties and structural characteristics of Fe/Pt multilayers after annealing at various temperatures in order to clarify the growth process of the ordered Fe–Pt phase in the Fe/Pt multilayer structures. It is found that rapid diffusion at Fe/Pt interface occurs at temperatures 275–325 °C and the multilayer structure directly transforms to the ordered (fct) phase when Fe and Pt layer thickness is almost equal. The ordering parameter S is evaluated to be 0.50–0.65 after annealing at 300–325 °C, and then is significantly enhanced to ∼1.00 with increasing annealing temperatures. By comparing the thermal processes of these different multilayer structures, it is found that the rapid formation of the fct phase in the multilayers with Fe/Pt≅1 is due to relatively rapid diffusion at the interface.