DEPHASING OF BALLISTIC ELECTRONS AS A FUNCTION OF TEMPERATURE AND CARRIER DENSITY

Dephasing of ballistic electrons is measured as a function of both temperature and Fermi energy in a high-mobility two-dimensional electron gas. We find a qualitative agreement between the measured phase-breaking length and the theoretical prediction for the electron-electron scattering length using the value of E(F) measured with large-area Hall bars. A good quantitative agreement is obtained when a local value of E(F), measured via on-chip magnetic focusing, is used. The good agreement between the measured phase-breaking length and the theoretical electron-electron scattering length strongly suggests that these two quantities are the same in the ballistic regime.