Effect of boundaries and impurities on electron-phonon dephasing

Electron scattering from boundaries and impurities destroys the single-part icle picture of the electron-phonon interaction. We show that quantum inter ference between 'pure' electron-phonon and electron-boundary/impurity scatt ering may result in the reduction as well as to the significant enlargement of the electron dephasing rate. This effect crucially depends on the exten t, to which electron scatterers, such as boundaries and impurities, are dra gged by phonons. Static and vibrating scatterers are described by two dimen sionless parameters q(T)l and q(T)L, where q is the wavevector of the therm al phonon, l is the total electron mean-free path, L is the mean-free path due to scattering from static scatterers. According to the Pippard ineffect iveness condition [1], without static scatterers the dephasing rate at low temperatures is slower by the factor 1/ql than the rate in a pure bulk mate rial. However, in the presence of static potential the dephasing rate turns out to be 1/qL times faster. Thus, at low temperatures electron dephasing and energy relaxation may be controlled by electron boundary/impurity scatt ering in a wide range. (C) 2000 Academic Press.