On momentum relaxation processes during electron collisions in two-dimensional conducting systems

It is shown that momentum relaxation processes associated with collisions between electrons in a two-dimensional degenerate electron gas are characterized by quite different times τs and τa for electron distribution functions symmetric and antisymmetric with respect to the momentum. The ratio of these times is given by τa/τs ≈ (T/εF)2 (T is the temperature and εF the Fermi energy). The temperature dependence of the electron-electron drag effect in two parallel heterojunctions based on GaAs/AlGaAs is explained.