Electron Dephasing in Metallic Narrow Wires at Low Temperatures

The low temperature behavior of the electron phase coherence time in metals, ¿Á, is currently a subject of controversy. While theory predicts that ¿Á should increase on cooling as an inverse power law of temperature, many samples exhibit a saturation of ¿Á below a temperature between 0.1 and 1 K. In this paper we present evidence that the saturation of ¿Á often observed in weakly-disordered polycrystalline metals (Au, Ag, and Cu) is most likely due to a dilute concentration of paramagnetic impurities, either on the surface or in the bulk.