Domain wall magnetoresistance in permalloy half-ring wires

Submicron permalloy wires with half-ring and s-shape structure are designed. Magnetoresistance loops are measured between the sweeping field ±4000 Oe at varying angles between external field and longitudinal axis. The resistances in remanent state of s-shape wire are found to be almost same value for every angle. On the other hand, the resistances of half-ring wire are found to be decreasing with increasing angle. Magnetic force microscopy images of the wires confirm the varied resistances result from different domain structures on the corners with domain wall or without domain wall. The domain wall resistance (DWR) in half-ring wires is estimated to be about 0.31%. Theoretical calculations based on impurity scattering model and spin accumulation model are done to validate the experimental data. DWR from spin accumulation model is 0.012%∼0.031% and from impurity scattering model, it is 0.15%∼0.33%.