Ordering temperature of L10-FePd film reduced by Ag underlayer

The microstructure and magnetic properties of FePd and Ag/FePd films prepared by magnetron sputtering and vacuum annealing are investigated. The ordering temperature of L10-FePd phase is greatly reduced by Ag underlayer. Furthermore, the axial ratio of Ag/FePd is much lower than that of FePd, even smaller than the bulk value, indicating the formation of better tetragonality. The introduction of Ag underlayer increases the coercivity and suppressed intergrain exchange coupling of FePd grains. Microstructure analyses reveal that Ag atoms diffuse into the inner part, even to the surface of the film, which favors the rearrangement of Fe and Pd atoms, leading to the promotion of L10-FePd phase.

► The introduction of Ag underlayer significantly improves the magnetic properties.
► The ordering temperature of L10-FePd phase is greatly reduced by the Ag underlayer.
► The axial ratio of Ag/FePd is much lower than that of FePd.
► The intergrain exchange coupling of FePd grains is suppressed by Ag atoms at the boundaries.