Detection of paired domain walls in a ferromagnetic ring by a bend resistance measurement

We have investigated dynamics of paired domain walls in a microfabricated ferromagnetic ring by using a ballistic transport character of a two-dimensional electron gas (2DEG) microcross. The stray field from the domain walls results in a change in the bend resistance of the 2DEG cross lying beneath the ferromagnetic ring depending on the positions of the domain walls. The measurements for different directional angles of the applied magnetic field reveal that the domain wall behavior is strongly affected by identical local defects in the ring. We have also studied a response of paired domain walls under a pulsed magnetic field. We find that the paired domain walls switch the positions without annihilation under a pulsed magnetic field with a short rise time.