Nonequilibrium electron distribution and nonlocal resistance in a two-dimensional electron gas at high magnetic fields

Abstract

The nonlocal resistance arising from the nonequilibrium electron distribution at edge states in 2DEG devices is experimentally studied and theoretically analyzed. The analysis takes account of the finite relaxation of the electron population between the highest (occupied) Landau level and the lower Landau levels in terms of the equilibration length L eq. The resistivities, ϱ N xx and ϱ N xy , in the topmost bulk Landau level are experimentally determined in ‘closed’ devices, in which a 2DEG is (almost) completely bounded by ohmic contacts, and are used to explain the resistance in the devices with edge states. The analysis shows that L eq increases exponentially with increasing magnetic field. A remarkable nonlinearity of the phenomena arising at higher current levels is also studied experimentally and theoretically. An overpopulation of the topmost Landau level along with a partial evacuation of the adjacent (lower) Landau levels is expected in the nonlinear regime, which, in turn, predicts cyclotron emission from quantized Hall devices.