Swift heavy ion induced surface modification for tailoring coercivity in Fe-Ni based amorphous thin films

Fe-Ni based amorphous thin films were prepared by thermal evaporation. These films were irradiated by 108 MeV Ag⁸⁺ ions at room temperature with fluences ranging from 1× 10¹² to 3× 10¹³ ions/ cm² using a 15 UD Pelletron accelerator. Glancing angle x-ray diffraction studies showed that the irradiated films retain their amorphous nature. The topographical evolution of the films under swift heavy ion (SHI) bombardment was probed using atomic force microscope and it was noticed that surface roughening was taking place with ion beam irradiation. Magnetic measurements using a vibrating sample magnetometer showed that the coercivity of the films increases with an increase in the ion fluence. The observed coercivity changes are correlated with topographical evolution of the films under SHI irradiation. The ability to modify the magnetic properties via SHI irradiation could be utilized for applications in thin film magnetism.