New insulating phases of two-dimensional electrons in high Landau levels: observation of sharp thresholds to conduction

TL;DR

This paper reports the discovery of sharp thresholds to conduction in high Landau level quantum Hall states, revealing complex insulating and conducting phases likely related to charge density wave depinning.

Contribution

It provides experimental evidence of non-linear transport and hysteresis in high Landau levels, suggesting new insulating phases and transitions in 2D electron systems.

Findings

Observation of sharp conduction thresholds

Hysteretic transition to conducting state

Evidence for charge density wave depinning

Abstract

The intriguing re-entrant integer quantized Hall states recently discovered in high Landau levels of high-mobility 2D electron systems are found to exhibit extremely non-linear transport. At small currents these states reflect insulating behavior of the electrons in the uppermost Landau level. At larger currents, however, a discontinuous and hysteretic transition to a conducting state is observed. These phenomena, found only in very narrow magnetic field ranges, are suggestive of the depinning of a charge density wave state, but other explanations can also be constructed.