Ferromagnetism of FePt3 films induced by ion-beam irradiation

We demonstrate that chemically ordered FePt3 films can be altered from non-magnetic to ferromagnetic at room temperature by ion-beam irradiation. Both epitaxial and polycrystalline films were grown in the chemically ordered Ll2, phase and are non-magnetic at room temperature. Upon irradiation with 700 keV N+ ions at a dose of 1 x 1016 ions/ cm2 the chemical order is destroyed and ferromagnetism is induced. The magnetism of the irradiated film is compared to an as-deposited chemically disordered ferromagnetic FePt3 film by hysteresis, torque, and moment vs. temperature curves. The present results share a common origin to the ferrimagnetic-to-non-magnetic transition observed in CrPt3 films and may have potential application for patterned ferromagnetic structures and for studying exchange biasing of laterally patterned ferromagnetic/antiferromagnetic structures.