Domain wall displacement by current pulses injection in submicrometer Permalloy square ring structures

The magnetoresistance in submicrometer Permalloy square ring structures has been experimentally measured and modeled. The authors show that using an external field they can place a head-to-head domain wall at a selected corner of the ring and sense its position by magnetoresistance. They finally demonstrate that a domain wall can be reversibly and controllably displaced by current pulses of different polarity. Their observations can be explained by a directional spin-torque effect.