Individual-defect electromigration in metal nanobridges

Abstract

We have studied electromigration in metal nanobridges sufficiently small that individual-defect motion can be observed in the resistance noise. True electromigration occurs by a very complex process of a ‘‘defect glass’’ evolving in time under an applied bias, rather than by simple diffusion of independent defects. At lower biases, reversible precursors to electromigration provide quantitative information about the electromigration of individual defects. A random energy transfer from the electrons to the defects dominates the expected electromigration-force term, accelerating the electromigration process by heating the defects preferentially above the lattice temperature.