POSSIBLE MECHANISM FOR THE BREAKDOWN OF THE QUANTUM HALL-EFFECT

A quite simple mechanism of nonlinear current-voltage dependence in the quantum Hall effect regime is proposed. It is based on the specific electrostatics of a 2D strip and on the strong concentration dependence of sigma-xx, and does not rely on any microscopic nonlinearities in the local relation between current and electric field. It is shown that the predicted electric field and current density scales of nonlinearities in the current-voltage dependence are in agreement with experiments. Nonlinear corrections for low voltages are derived, while what happens at high voltages still remains to be understood.