Low-temperature electron dephasing time in AuPd revisited

Abstract

Ever since the first discoveries of the quantum-interference transport in mesoscopic systems, the electron dephasing times, $τ_ϕ$, in the concentrated AuPd alloys have been extensively measured. The samples were made from different sources with different compositions, prepared by different deposition methods, and various geometries (1D narrow wires, 2D thin films, and 3D thickfilms) were studied. Surprisingly, the low-temperature behavior of $τ_ϕ$ inferred by different groups over two decades reveals a systematic correlation with the level of disorder of the sample. At low temperatures, where $τ_ϕ$ is (nearly) independent of temperature, a scaling $τ_ϕ^{\rm max} \propto D^{-α}$ is found, where $tau_ϕ^{\rm max}$ is the maximum value of $τ_ϕ$ measured in the experiment, $D$ is the electron diffusion constant, and the exponent $α$ is close to or slightly larger than 1. We address this nontrivial scaling behavior and suggest that the most possible origin for this unusual dephasing is due to dynamical structure defects, while other theoretical explanations may not be totally ruled out.

to appear in Physica E, Proceedings for the International Seminar and Workshop "Quantum Coherence, Noise, and Decoherence in Nanostructures", 15-26 May 2006, Dresden