Is weak temperature dependence of electron dephasing possible?

TL;DR

This paper develops a first-principle theory explaining electron dephasing mechanisms involving dynamic defects, showing that dephasing rate can weakly depend on temperature and saturate at low temperatures, aligning with some experimental observations.

Contribution

It introduces a comprehensive theoretical model for electron dephasing by disorder-induced two state fluctuators, including mechanisms causing weak temperature dependence.

Findings

Dephasing rate saturates at low temperatures due to inelastic scattering.

Weak temperature dependence of dephasing rate explained by two mechanisms.

Dephasing rate tends to zero below a certain temperature depending on defect models.

Abstract

The first-principle theory of electron dephasing by disorder-induced two state fluctuators is developed. There exist two mechanisms of dephasing. First, dephasing occurs due to direct transitions between the defect levels caused by inelastic electron-defect scattering. The second mechanism is due to violation of the time reversal symmetry caused by time-dependent fluctuations of the scattering potential. These fluctuations originate from an interaction between the dynamic defects and conduction electrons forming a thermal bath. The first contribution to the dephasing rate saturates as temperature decreases. The second contribution does not saturate, although its temperature dependence is rather weak, $\propto T^{1/3}$. The quantitative estimates based on the experimental data show that these mechanisms considered can explain the weak temperature dependence of the dephasing rate in some temperature interval. However, below some temperature dependent on the model of dynamic defects the dephasing rate tends rapidly to zero. The relation to earlier studies of the dephasing caused by the dynamical defects is discussed.