Current-Driven Domain Wall Motion, Nucleation, and Propagation in a Co/Pt Multi-Layer Strip with a Stepped Structure

We have proposed detecting a domain wall behavior in a strip with perpendicular magnetic anisotropy by measuring both extraordinary Hall effect and domain wall resistance with unique placement of three via contacts. By using this detecting technique, we have confirmed that the domain wall can be initialized at the boundary of the stepped structure of a Co/Pt multilayer strip. We have observed nucleation independent of the current direction and the propagation depending on it. We could not find any domain wall motion by spin-transfer torque from the boundary until 1.8 times 10¹² A/m², probably because of the smaller polarization and/or the larger damping constant of the Co/Pt multilayer.