Magnetoresistance and magnetization reversal of single Co nanowires

The magnetization reversal in Co single wires was investigated through magnetoresistance measurements and micromagnetic simulations. We developed a model to calculate the magnetoresistance based on the magnetization structure obtained by the solution of the Landau-Lifshitz-Gilbert equation. It allowed us to understand details of the magnetoresistance curves, including the jumps that are related to the magnetization reversal process. Depending on the angle between the wire and the applied magnetic field, simulations show that the magnetization structure exhibits curling or uniform rotation modes in the magnetization reversal process. In the curling mode, the magnetization structure exhibits a vortex along the wire with its core displaced from the wire axis. For angles larger than 50° the vortex core is close to the wire surface and disappears at 80°, changing the mode from curling to uniform rotation. Our model for computing the magnetoresistance revealed to be a useful tool in the understanding of magnetic properties of nanostructures.