Current filamentation in GaAs/AlGaAs heterojunctions preceding quantum-Hall-effect breakdown

Self-induced filamentation of the current near the edges of a sample in the Hall geometry has been observed in the quantum-Hall-effect regime in a two-dimensional electronic system arising near a GaAs/AlGaAs heterojunction. If in the case of integer values of the filling factor nu averaged over the sample the currents flowing along opposite edges are approximately the same, then away from such a value within the quantum plateau the current is increasingly concentrated near that edge of the sample where the local value of nu is closer to being an integer. When the direction of the magnetic field or of the current changes, the filament switches to the opposite edge of the sample. (C) 1998 American Institute of Physics. [S0021-3640(98)00921-9].