Vortex-assisted domain wall depinning and propagation in notched nanowires

Various notches are often introduced in spintronics to trap a domain wall (DW). Common wisdom would expect notches to strengthen DW pinning and to hinder DW motion. Interestingly, our simulations show that notches help electric current to depin a DW with the assistance of vortex generation. The DW displacement is insensitive to notch geometry and current density. This phenomenon is explained by the Thiele equation. Moreover, a current density below the intrinsic threshold value, which is the minimum current to sustain continuous DW motion in a uniform nanowire, can induce a continuous DW propagation along a wire with a series of notches.