Reentrant fractional quantum Hall states in bilayer graphene: Controllable, driven phase transitions

TL;DR

This paper theoretically demonstrates that in biased bilayer graphene, phase transitions between fractional quantum Hall states and compressible states can be controlled by tuning the bandgap or electron density, revealing unique tunability not seen in traditional systems.

Contribution

It introduces the concept of controllable, driven phase transitions in fractional quantum Hall states specifically in bilayer graphene, a phenomenon not observed in conventional semiconductor systems.

Findings

Tuning bandgap induces phase transitions from incompressible to compressible states.

Varying electron density causes transitions between different FQHE states and compressible states.

Unique tunability of FQHE states in bilayer graphene compared to traditional materials.

Abstract

Here we report from our theoretical studies that in biased bilayer graphene, one can induce phase transitions from an incompressible state to a compressible state by tuning the bandgap at a given electron density. Likewise, variation of the density with a fixed bandgap results in a transition from the FQHE states at lower Landau levels to compressible states at intermediate Landau levels and finally to FQHE states at higher Landau levels. This intriguing scenario of tunable phase transitions in the fractional quantum Hall states is unique to bilayer graphene and never before existed in conventional semiconductor systems.