Angle-resolved spectroscopy of electron-electron scattering in a 2D system

Electron-beam propagation experiments have been used to determine the energy and angle dependence of electron-electron (ee) scattering in a two-dimensional electron gas (2DEG) in a very direct manner. The experimental results provide direct evidence for novel ee-scattering effects in 2D degenerate conductors. Most striking is the increased importance of small-angle scattering in a 2D system with decreasing excitation energy. In particular, in a 2DEG ee-scattering can, at sufficiently low energies, be purely dephasing in character, i.e. changing the phase but not the direction of electron motion.