Iron-implanted epitaxial palladium thin films: Structure, ferromagnetism and signatures of spinodal decomposition

We report on the formation of the dilute Pd1-xFex composites with tunable magnetic properties under ion-beam implantation of epitaxial Pd thin films. Binary Pd1-xFex alloys with a mean iron content x of 0.025, 0.035, and 0.075 were obtained by the implantation of 40 keV Fe+ ions into the palladium films on MgO (001) substrate to the doses of 0.5 x 10(16), 1.0 x 10(16) and 3.0 x 10(16) ions/cm(2), respectively. Structural and magnetic studies have shown that iron atoms occupy regular fcc-lattice Pd-sites without the formation of any secondary crystallographic phase. All the iron implanted Pd films reveal ferromagnetism at low temperatures. The observed multiple ferromagnetic resonances in the implanted Pd1-xFex films indicate a formation of a magnetically inhomogeneous state due to spinodal decomposition into regions, presumably layers, with identical crystal symmetry but different iron contents. The multiphase composite magnetic structure is robust with respect to the vacuum annealing at 770 K, though develops towards well-defined local Pd/Fe ratios.