TMR effects of sputtered Fe-Al-O granular films after irradiation by high energy ions

Fe-Al-O granular films prepared by rf-sputtering were irradiated at room temperature with 1.8 and 2.8 MeV C ions and 2.8 MeV Ge ions to investigate the effects of irradiation-induced defects to the microscopic structure in the film and also the magnetic properties. Using conversion electron Moessbauer spectroscopy, it is observed that the dispersed state of nanosized iron particles is significantly affected by the irradiation at a dose range of 1015-1016 ions/cm2, and that the change in the dispersion results in a decrease of the magnetoresistance ratio. The results suggest that the aggregation of iron particles is promoted by the irradiation