T. C. Lee | Searcharxiv

arXiv2007

Observation of strong electron dephasing in disordered Cu$_{93}$Ge$_4$Au$_3$ thin films

We report the observation of strong electron dephasing in a series of disordered Cu$_{93}$Ge$_4$Au$_3$ thin films. A very short electron dephasing time possessing very weak temperature dependence around 6 K, followed by an upturn with further decrease in temperature below 4 K, is found. The upturn is progressively more pronounced in more disordered samples. Moreover, a ln$T$ dependent, but high-magnetic-field-insensitive, resistance rise persisting from above 10 K down to 30 mK is observed in the films. These results suggest a nonmagnetic dephasing process which is stronger than any known mechanism and may originate from the coupling of conduction electrons to dynamic defects.

cond-mat.mes-hall↗

arXiv2007

Low-temperature electron dephasing time in AuPd revisited

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.

cond-mat.mes-hall↗