Ultrahigh current densities in Permalloy nanowires on diamond

To study the forces of spin polarized currents on domain walls in the microscopic scale, dc densities in the order of 10(12) A/m(2) are required. In general, current densities of this magnitude cause a rapid destruction of metallic wires. We present a device that allows us to apply current densities of 1.5x10(12) A/m(2) for more than an hour without degradation in the wire, using a diamond substrate as heat spreader. Annealing effects are observed and the wire temperature is measured and modeled as function of the current density. (C) 2008 American Institute of Physics.