Current Induced Tilting of Domain Walls in High Velocity Motion along Perpendicularly Magnetized Micron-Sized Co/Ni/Co Racetracks

Kerr microscopy is used to investigate domain wall motion in response to nanosecond-long current pulses in perpendicularly magnetized micron-sized Co/Ni/Co racetracks. Domain wall velocities greater than 300 m/s are observed. The velocity is independent of the pulse length for a wide range of current densities. However, the domain wall dynamics depends on the pulse length just above the threshold current for motion, where slow creep motion occurs, and at very high current densities, where domain nucleation takes place. We also observe a tilting of the domain wall that cannot be accounted for by the Oersted field from the driving current. (C) 2012 The Japan Society of Applied Physics