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

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 (tau(p)*) as a function of energy near the Fermi energy. Close to the Fermi energy, the spin evolution is oscillatory P 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 tau(p)* are extracted by using a Monte Carlo simulation method. At the Fermi energy, tau(p)* is very close to the ensemble momentum relaxation time (tau(p)) obtained from the electron mobility. For higher energies, tau(p)* falls quadratically, which is consistent with the theoretical expectations for the onset of the electron-electron P scattering, which is inhibited by the Pauli principle at the Fermi energy.