paper

Dephasing of Electrons in Mesoscopic Metal Wires

arXiv:cond-mat/0302235 · doi:10.1103/PhysRevB.68.085413

Abstract

We have extracted the phase coherence time of electronic quasiparticles from the low field magnetoresistance of weakly disordered wires made of silver, copper and gold. In samples fabricated using our purest silver and gold sources, increases as when the temperature is reduced, as predicted by the theory of electron-electron interactions in diffusive wires. In contrast, samples made of a silver source material of lesser purity or of copper exhibit an apparent saturation of starting between 0.1 and 1 K down to our base temperature of 40 mK. By implanting manganese impurities in silver wires, we show that even a minute concentration of magnetic impurities having a small Kondo temperature can lead to a quasi saturation of over a broad temperature range, while the resistance increase expected from the Kondo effect remains hidden by a large background. We also measured the conductance of Aharonov-Bohm rings fabricated using a very pure copper source and found that the amplitude of the conductance oscillations increases strongly with magnetic field. This set of experiments suggests that the frequently observed ``saturation'' of in weakly disordered metallic thin films can be attributed to spin-flip scattering from extremely dilute magnetic impurities, at a level undetectable by other means.

arXiv comment16 pages, 11 figures, to be published in Physical Review B

References in corpus (17)

Cited by in corpus (155)