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

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 degreesC 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 degreesC, and then is significantly enhanced to similar to1.00 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 congruent to 1 is due to relatively rapid diffusion at the interface. (C) 2001 American Institute of Physics.