NUCLEATION OF MAGNETIZATION REVERSAL IN INDIVIDUAL NANOSIZED NICKEL WIRES

The switching of the magnetization of single Ni wires with diameters 4 0-100 nm was measured at temperatures between 0.13 and 6 K. The angula r dependence of the switching field was studied for several wire diame ters. Repetitive measurements allow us to obtain histograms of the swi tching field values. For the smallest diameters, the measurements of t he probability of reversal revealed a thermally activated switching fo llowing an Arrhenius law with an activation volume much smaller than t he volume of the wire.