Magnetoresistance dependence on electrical contact geometry and field alignment in mesoscopic rectangular rings

We investigate the magnetoresistance (MR) responses in a ferromagnetic rectangular ring structure using a four-point probe technique. The measured MR curves are strongly dependent on the electrical contact geometries used. The associated MR characteristics are elucidated by a combination of micromagnetic simulations and resistor-network based model, and the MR contributions from different portions of the ring were studied quantitatively. The systematic angular MR measured at the ring corner further show that the locations of the domain wall nucleation are very sensitive to the field alignment.