Interaction-Induced Dephasing in Disordered Electron Systems
The destructive effect of the electron-electron interaction on weak localization phenomena in disordered metals is studied. We associate this effect with a cutoff in the particle-particle diffusion propagator (Cooperon) in the presence of the interaction. This cutoff, also called dephasing rate, is evaluated diagrammatically in the lowest order of the perturbation theory in the screened Coulomb interaction and in the disorder strength. Unlike in previous studies, we explicitly take into account the interaction processes with energy exchange between the upper and the lower electron lines entering the Cooperon propagator and directly solve the integral equation obtained. Besides, special care is taken to treat the virtual processes with energy transfer larger than temperature (quantum fluctuations). We accurately keep all the contributions coming from them, not appealing to the known semi-classical procedure which reduces the effect of the interaction to that of a fluctuating external field. It is demonstrated that the quantum fluctuations only lead to a rescaling of the momentum and frequency dependences of the Cooper pole but do not affect its cuto.. Thus, we do not confirm the idea that “zero-point fluctuations” can dephase electrons. In contrast, the processes with energy transfer smaller than temperature do that. The temperature dependence of the dephasing rate due to such processes for quasi-1D and -2D conductors is analyzed.