Electron Dephasing in Mesoscopic Metal Wires

TL;DR

This paper investigates electron phase coherence time in mesoscopic metal wires at low temperatures, finding no saturation in pure samples and confirming theoretical predictions, while addressing previous conflicting results and criticisms.

Contribution

The study provides experimental evidence that in pure Ag and Au wires, electron dephasing time follows theoretical predictions without saturation down to 40 mK.

Findings

No saturation of $ au_{phi}$ in pure samples at low temperatures.

Measured $ au_{phi}$ agrees with Altshuler, Aronov, and Khmelnitskii theory.

Saturation observed in other samples may be due to impurities or extrinsic effects.

Abstract

The low-temperature behavior of the electron phase coherence time, $\tau_{\phi}$, in mesoscopic metal wires has been a subject of controversy recently. Whereas theory predicts that $\tau_{\phi}(T)$ in narrow wires should increase as $T^{-2/3}$ as the temperature $T$ is lowered, many samples exhibit a saturation of $\tau_{\phi}$ below about 1 K. We review here the experiments we have performed recently to address this issue. In particular we emphasize that in sufficiently pure Ag and Au samples we observe no saturation of $\tau_{\phi}$ down to our base temperature of 40 mK. In addition, the measured magnitude of $\tau_{\phi}$ is in excellent quantitative agreement with the prediction of the perturbative theory of Altshuler, Aronov and Khmelnitskii. We discuss possible explanations why saturation of $\tau_{\phi}$ is observed in many other samples measured in our laboratory and elsewhere, and answer the criticisms raised recently by Mohanty and Webb regarding our work.