Swift ion irradiations of natFe/57Fe/Si trilayers

We report here on changes in magnetism and microstructure when implanting, at 92 or 300 K, up to 5 x 10 15 Au 26+ -ions cm -2 of 350 MeV into nat Fe(45 nm)/ 57 Fe(20 nm)/Si trilayers. This choice of ions and energy allowed to test the irradiation effects in the regime of pure electronic stopping. The samples were analysed before and after irradiation by Rutherford back-scattering spectroscopy, X-ray diffraction, conversion electron Mossbauer spectroscopy, and magneto-optical Kerr effect. Up to 1 x 10 15 ions cm -2 , there was interface broadening at a mixing rate of Δσ 2 /Φ = 55(5) nm 4 , followed by full Fe-Si inter-diffusion. The Mossbauer spectra revealed fractions of α-Fe and amorphous ferromagnetic and paramagnetic iron silicides, but no crystalline Fe-Si phase. The magnetic remanence in the as-deposited Fe-layer showed small components of uniaxial and four-fold magnetization. For increasing ion fluence, the component with four-fold symmetry grew at the expense of the uniaxial component. For the highest fluences, an isotropic magnetization was found.