Effects of ion irradiation on ferromagnetic thin films

The effects of ion beam irradiation on the magnetic properties of thin Permalloy films have been examined experimentally, using the ion species He+, Ar+, Xe+, C+, N+, O+ and Si+, at energies chosen either to implant within the film or to produce kinetic effects in the film during transmission. Hysteresis loop parameters, magnetoresistance measurements and XRD were used to characterize the samples before and after exposure. The principal results seen were a loss of uniaxial anisotropy and an increase of coercivity, being attributed to collisional damage of the Permalloy lattice structure and the introduction of extended defects. Effects of film stress and implanted impurities were also identified.