Atypical Fractional Quantum Hall Effect in Graphene at Filling Factor 1/3

TL;DR

This paper investigates a fractional quantum Hall state in graphene at filling factor 1/3, revealing unique spin-flip excitations and complex properties beyond the conventional Laughlin state, with implications for experimental detection.

Contribution

It introduces a four-component trial wave function and exact diagonalization analysis to characterize the graphene FQH state at ν=1/3, highlighting novel physical properties.

Findings

Connected to Laughlin state in upper spin branch

Presence of low-energy spin-flip excitations

Potential observation via inelastic light scattering

Abstract

We study the recently observed graphene fractional quantum Hall state at a filling factor $\nu_G=1/3$ using a four-component trial wave function and exact diagonalization calculations. Although it is adiabatically connected to a 1/3 Laughlin state in the upper spin branch, with SU(2) valley-isospin ferromagnetic ordering and a completely filled lower spin branch, it reveals physical properties beyond such a state that is the natural ground state for a large Zeeman effect. Most saliently, it possesses at experimentally relevant values of the Zeeman gap low-energy spin-flip excitations that may be unveiled in inelastic light-scattering experiments.