Spatially resolved monitoring of the evolution of the breakdown of the quantum hall effect: Direct observation of inter-landau-level tunneling

Abstract

We have measured the evolution of breakdown of the quantum Hall effect along a macroscopic constriction on a GaAs/AlGaAs 2DEG heterostructure. From the evolution of the dissipative resistivity along the drift direction, we conclude that electrons are excited to the upper Landau level at a constant rate which exponentially depends on the Hall voltage. The results are explained on the basis of impurity mediated tunneling of electrons between the Landau levels.