Magnetoresistance and switching of electrochemically etched Ni wires

Nickel wires, a few 100 nm in diameter, with a resistance up to 20 Ω, have been prepared by controlled electrochemical etching of macroscopic wires. Although the wires are polycrystalline and the presence of domain walls can be inferred directly from the magnetoresistance curves, the switching field, HSW, for complete reversal is insensitive to details of the wire diameters provided their aspect ratio is larger than 100. Order of magnitude arguments show evidence for spin accumulation at domain walls, while the angular dependence HSW(ϑ) with respect to the wire axis is well described by the analytical form of the curling model, indicating a wider range of applicability of this model than previously thought.