Field and Current Driven Magnetic Domain Wall Motion in Disordered A1-FePt Nanowires

Arc-shaped magnetic FePt nanowires (10nm thick, 375nm wide) displaying in-plane anisotropy were fabricated. A vortex domain wall was formed in the middle of the arc after in-plane saturation in a field perpendicular to the wire. Translational domain wall propagation was observed at a field of 40 Oe applied parallel to the wire, while complete propagation to the end of the arc occurred at 100 Oe. Domain wall displacement at low velocity was achieved by current pulses of 2.5 10¹¹ A m² at zero applied magnetic field, comparable to the zero-field threshold current density of Permalloy. A field-assisted spin transfer torque drove the domain wall 1.8m to the end of the arc.