Nucleation of Magnetization Reversal in Individual Nanosized Nickel Wires

The switching of the magnetization of single Ni wires with diameters 40-100 nm was measured at temperatures between 0.13 and 6 K. The angular dependence of the switching field was studied for several wire diameters. Repetitive measurements allow us to obtain histograms of the switching field values. For the smallest diameters, the measurements of the probability of reversal revealed a thermally activated switching following an Arrhenius law with an activation volume much smaller than the volume of the wire.