Possible existence of a band of extended states induced by inter-Landau-band mixing in quantum Hall system

TL;DR

This paper proposes that inter-Landau-band mixing can induce extended state bands in quantum Hall systems, leading to a new phase diagram with a metallic phase, supported by numerical simulations and reanalysis of experimental data.

Contribution

It introduces the concept of extended state bands caused by inter-Landau-band mixing and proposes a new phase diagram with a metallic phase in quantum Hall systems.

Findings

Numerical calculations show possible formation of extended state bands.

Reanalysis of experimental data supports the new phase diagram.

Finite-size effects require further investigation for conclusive results.

Abstract

The mixing of states with {\it opposite chirality} in quantum Hall system is shown to have delocalization effect. It is possible that extended states may form bands because of this mixing, as is shown through a numerical calculation on a two-channel network model. Based on this result, a new phase diagram with a narrow {\it metallic} phase separating two adjacent QH phases and/or separating a QH phase from the insulating phase is proposed. The data from recent non-scaling experiments is reanalyzed and shown that they seem to be {\it consistent} with the new phase diagram. However, due to finite-size effects, further study on large system size is still needed to conclude whether there are extended state bands in thermodynamic limit.