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

Dephasing of ballistic electrons is measured as a function of both tem perature and Fermi energy in a high-mobility two-dimensional electron gas. We find a qualitative agreement between the measured phase-breaki ng length and the theoretical prediction for the electron-electron sca ttering length using the value of E(F) measured with large-area Hall b ars. A good quantitative agreement is obtained when a local value of E (F), measured via on-chip magnetic focusing, is used. The good agreeme nt between the measured phase-breaking length and the theoretical elec tron-electron scattering length strongly suggests that these two quant ities are the same in the ballistic regime.