Impact of stoichiometry on L10 ordering in FePt and FePtCu thin films

The L10 ordering kinetics strongly depend on the films initial Fe/Pt atomic ratio. FexPt100-x films with <f>x<50</f> at.% benefit from Cu addition since the Cu is expected to alloy with the FePt as an Fe atom replacement. The addition of Cu is less remarkable in films that start with an equiatomic Fe and Pt composition. In that case, Cu decreases the ultimate film coercivity and does not significantly improve the L10 ordering process. Large fields (9 T) are required to fully saturate the (1 1 1) textured L10 ordered FePt(Cu) films. It has been theoretically suggested that the moment of ordered FePt decreases due to ferrimagnetic alignment of the Fe and Pt moments; however, in these experiments the <f>Ms</f> value did not change significantly with annealing treatment and subsequent L10 ordering. [Copyright &y& Elsevier]