Current-induced domain-wall motion in U-shaped permalloy wire

The current-induced domain-wall motion has been observed by using a U-shaped permalloy wire. We observed two magnetic states in a U-shaped pattern. One is the vortex domain wall at the center of semicircular arc region of the U-shaped pattern, and the other is the continuous magnetic state without the domain wall in between. In general, the current density of the order of /spl sim/10/sup 7/ A/cm/sup 2/ is needed to drive a magnetic domain wall. In this paper, the critical current for domain-wall motion increases as the bias field increases. The bias field means the field deviated from the switching field of the wire.