Field- and current-induced domain-wall motion in permalloy nanowires with magnetic soft spots

We study field- and current-induced domain-wall motion in permalloy nanowires comprising a square-shaped magnetically softened region. Implantation of chromium ions is used to induce pinning sites via a local reduction of the saturation magnetization. Micromagnetic simulations, magnetic transmission soft X-ray microscopy, and electrical measurements are employed to char- acterize the pinning potential which significantly differs for transverse and vortex walls. Reliable domain-wall depinning from a so-called magnetic soft spot by single current pulses is observed. This demonstrates the suitability of these pinning sites for applications.