Giant enhancement of the domain wall velocity in irradiated ultrathin magnetic nanowires

Domain wall velocity measurements in ultrathin Pt/Co(0.6 nm)/Pt narrow magn etic wires with perpendicular anisotropy are reported. Tracks (0.45 and 0.9 microns wide) are defined by drawing twins of parallel etched/irradiated l ines with a focused Ga+ beam (FIB). In these films, irradiation induces a l arge decrease in coercivity due to Co-Pt intermixing at the interfaces, as checked in areas submitted to various fluences. At the same field, the doma in wall propagates at far higher velocities in a 0.45 mum track than in the virgin film. It is explained by the calculated irradiation fluence profile . Hence, irradiation can be used to design structures where the magnetic in formation propagates very rapidly under a small applied field.