Edge channels and the quantum-Hall-effect breakdown

Abstract
Quantum Hall devices have been investigated in the regime of the breakdown of dissipationless current flow by means of a photoresistance imaging technique. It is possible to distinguish three stages in development of the breakdown: (i) the initial rise of the longitudinal resistance due to a change with the Hall electric field of the percolation threshold leading to electron backscattering between the edges; (ii) at higher bias currents a strong response from the edges is observed in two-dimensional images, in agreement with the edge-state model; (iii) on increasing the bias current further, electron heating effects are seen to prevail.