Anisotropic magnetoresistance as a probe of magnetization reversal in individual nano-sized nickel wires

Magnetization reversal of individual Ni nanowires has been studied by anisotropic magnetoresistance (AMR) measurements. The wires are homogeneous cylinders 6μ long and averaging 80 nm in diameter. Nanowires were produced by electrodeposition in track-etched membrane templates. Electrical contacts to as-deposited single nanowires were obtained by a novel in-situ method where contact to a single wire is accomplished automatically and reliably during electrodeposition. Steps of the magnetoresistance are detected, corresponding to irreversible switching of the magnetization in a single wire. The dependence of the switching field on the orientation of the applied field as seen by AMR is identical to that recently observed by using micro-SQVID techniques.