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

• Ion-beam implantation of thin epitaxial palladium films with iron. • Spinodal decomposition into ‘stable phases’ of the palladium-iron system. • Ferromagnetic composite formation. • Multiple ferromagnetic resonances emerge consecutively with temperature lowering. • Lower coercivity of iron-implanted palladium films against molecular-beam epitaxy grown ones. We report on the formation of the dilute Pd 1− x Fe x composites with tunable magnetic properties under ion-beam implantation of epitaxial Pd thin films. Binary Pd 1− x Fe x 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 (0 0 1) substrate to the doses of 0.5 × 10 16 , 1.0 × 10 16 and 3.0 × 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 Pd 1− x Fe x 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.