Controlled and Reproducible Domain Wall Displacement by Current Pulses Injected into Ferromagnetic Ring Structures

In a combined numerical and experimental study, we demonstrate that current pulses of different polarity can reversibly and controllably displace a magnetic domain wall (DW) in submicrometer permalloy (NiFe) ring structures. The critical current densities for DW displacement are correlated with the specific spin structure of the DWs and are compared to results of micromagnetic simulations including a spin-torque term. Using a notch, an attractive local pinning potential is created for the DW resulting in a highly reproducible spin structure of the DW, critical for reliable current-induced switching.