Energy-dependent electron-electron scattering and spin dynamics in a two-dimensional electron gas

Abstract

The measurement of spin dynamics of electrons in a degenerate two-dimensional electron gas, wherein the Dyakonov--Perel mechanism is dominant, has been used to investigate the electron scattering time $({\ensuremath{\tau}}_{p}^{*})$ as a function of energy near the Fermi energy. Close to the Fermi energy, the spin evolution is oscillatory, which indicates a quasicollision-free regime of spin dynamics. As the energy is increased, a transition to an exponential, collision-dominated spin decay occurs. The oscillation frequency and the value of ${\ensuremath{\tau}}_{p}^{*}$ are extracted by using a Monte Carlo simulation method. At the Fermi energy, ${\ensuremath{\tau}}_{p}^{*}$ is very close to the ensemble momentum relaxation time $({\ensuremath{\tau}}_{p})$ obtained from the electron mobility. For higher energies, ${\ensuremath{\tau}}_{p}^{*}$ falls quadratically, which is consistent with the theoretical expectations for the onset of the electron-electron scattering, which is inhibited by the Pauli principle at the Fermi energy.