Time-dependent universal conductance fluctuations and coherence in AuPd and Ag

TL;DR

This study compares coherence lengths from different quantum transport measurements in AuPd and Ag, revealing strong agreement in AuPd but discrepancies in Ag, and discusses underlying dephasing mechanisms.

Contribution

It provides a detailed comparison of coherence lengths from weak localization and conductance fluctuations in AuPd and Ag, highlighting material-dependent differences and analyzing theoretical models.

Findings

Strong agreement in AuPd coherence lengths from both methods

Discrepancies in Ag below 10 K suggest complex dephasing effects

Discussion of high drive level suppression of conductance fluctuations

Abstract

Quantum transport phenomena allow experimental assessment of the phase coherence information in metals. We report quantitative comparisons of coherence lengths inferred from weak localization magnetoresistance measurements and time-dependent universal conductance fluctuation data. We describe these two measurements and their analysis. Strong agreement is observed in both quasi-2D and quasi-1D AuPd samples, a metal known to have high spin-orbit scattering. However, quantitative {\it disagreement} is seen in quasi-1D Ag wires below 10 K, a material with intermediate spin-orbit scattering. We consider explanations of this discrepancy, with particular emphasis on the theoretical expressions used to analyze the field dependence of the conductance fluctuations. We also discuss the mechanism of the suppression of conductance fluctuations at high drive levels, and dephasing mechanisms at work in these systems.