Dephasing of electrons in mesoscopic metal wires

摘要: We have extracted the phase coherence time ${\ensuremath{\tau}}_{\ensuremath{\varphi}}$ of electronic quasiparticles from low field magnetoresistance weakly disordered wires made silver, copper, and gold. In samples fabricated using our purest silver gold sources, increases as ${T}^{\ensuremath{-}2/3}$ when temperature T is reduced, predicted by theory electron--electron interactions in diffusive wires. contrast, a source material lesser purity or copper exhibit an apparent saturation starting between 0.1 1 K down to base 40 mK. By implanting manganese impurities wires, we show that even minute concentration magnetic having small Kondo can lead quasisaturation over broad range, while resistance increase expected effect remains hidden large background. also measured conductance Aharonov--Bohm rings very pure found amplitude $h/e$ oscillations strongly with field. This set experiments suggests frequently observed ``saturation'' metallic thin films be attributed spin--flip scattering extremely dilute impurities, at level undetectable other means.