# Even denominator fractional quantum Hall state in bilayer graphene

## TL;DR

This paper reports the observation of a robust even-denominator fractional quantum Hall state in high-mobility bilayer graphene, demonstrating its potential as a platform for studying non-Abelian topological states.

## Contribution

The study provides the first clear transport evidence of a tunable, robust even-denominator FQHE in bilayer graphene, highlighting its unique Landau level spectrum and controllability.

## Key findings

- Observation of a stable even-denominator FQHE in bilayer graphene.
- The energy gap of the state can be tuned by electric and magnetic fields.
- Mapping of the phase diagram shows the state’s dependence on external parameters.

## Abstract

The multi-component nature of bilayer graphene (BLG), together with the ability to controllably tune between the various ground state orders, makes it a rich system in which to explore interaction driven phenomena. In the fractional quantum Hall effect (FQHE) regime, the unique Landau level spectrum of BLG is anticipated to support a non-Abelian even-denominator state that is tunable by both electric and magnetic fields. However, observation of this state, which is anticipated to be stronger than in conventional systems, has been conspicuously difficult. Here we report transport measurements of a robust even denominator FQHE in high-mobility, dual gated BLG devices. We confirm that the stability of the energy gap can be sensitively tuned and map the phase diagram. Our results establish BLG as a dynamic new platform to study topological ground states with possible non-Abelian excitations.