Pulsed-current controlled magnetic domain wall motion in a patterned Permalloy film
These images of 40 um x 25 um in size were obtained by sequential MFM scans after each current pulse. The motion of the walls is best seen by noting the relative displacement with respect to the fixed topographical defects (white dots). The displacement of Bloch walls as far as 200 um along the strip was observed. The direction of domain wall motion was in the same direction with the electron flow, i.e. opposite to the current direction. The displacement per pulse was dependent on the sample thickness and current density. In general, wall displacement occurs when a critical current density on the order of 1011A/m2 is reached. This experiment clearly demonstrate the feasibility of using short current pulses as control signals to alter magnetization of a specific area of the surface.