Domain wall drag due to dc current injection into ferromagnetic nano-wires

We here experimentally demonstrate the domain wall depinning triggered by injecting the current into the domain wall. The domain wall is pinned at the connection of a large pad and a narrow wire prior to the current injection experiment. The pinned domain wall is freed and pushed into the wire at the critical current, only when the current is injected along the direction of the domain wall propagation. These results imply that the injection of the spin-polarized current into the domain wall causes additional magnetic pressure due to the spin-momentum transfer between the spin-polarized current and the localized magnetic moment.