Enlarged magnetic focusing radius of photoinduced ballistic currents

摘要

We exploit GaAs-based quantum point contacts as mesoscopic detectors toanalyze the ballistic flow of photogenerated electrons in a two-dimensionalelectron gas at a perpendicular magnetic field. Whereas charge transportexperiments always measure the classical cyclotron radius, we show that thischanges dramatically when detecting the photoinduced non-equilibrium current inmagnetic fields. The experimentally determined radius of the trajectoriessurprisingly exceeds the classical cyclotron value by far. Monte Carlosimulations suggest electron-electron scattering as the underlying reason.