Short-circuiting effect on the magnetoresistance of microstructured permalloy rings

We present a systematic investigation of the current/voltage lead effect on magnetization reversal of microstructured permalloy rings. The magnetic rings with film thickness of 23 nm and outer/inner diameter of 5/3 μm, respectively, were patched by nonmagnetic gold leads designed with various angles, 10°, 20°, and 30°. Longitudinal magnetoresistance measurement was adopted to demonstrate the short-circuiting effect. The mechanism can be attributed to the formation of the vortex structures developed beneath the lead-covered areas, in which the vortex pair domain configuration was confirmed using a magnetic force microscopy.