Fractional Quantum Hall Effect in Graphene

TL;DR

This paper discusses the unique fractional quantum Hall effects in graphene, highlighting how its pseudospin degeneracy and Dirac spectrum lead to novel quantum phenomena distinct from traditional systems.

Contribution

It introduces the potential for observing new fractional quantum Hall states in graphene due to its pseudospin degeneracy and Dirac spectrum, expanding understanding of quantum Hall physics.

Findings

Graphene's pseudospin degeneracy does not couple to magnetic field.

Predicted more robust fractional quantum Hall effect in graphene's second Landau level.

Identification of new integral and fractional quantum Hall phenomena in graphene.

Abstract

Unlike regular electron spin, the pseudospin degeneracy of Fermi points in graphene does not couple directly to magnetic field. Therefore, graphene provides a natural vehicle to observe the integral and fractional quantum Hall physics in an elusive limit analogous to zero Zeeman splitting in GaAs systems. This limit can exhibit new integral plateaus arising from interactions, large pseudoskyrmions, fractional sequences, even/odd numerator effects, composite-fermion pseudoskyrmions, and a pseudospin-singlet composite-fermion Fermi sea. The Dirac nature of the B=0 spectrum, which induces qualitative changes in the overall spectrum, has no bearing on the fractional quantum Hall effect in the $n=0$ Landau level of graphene. The second Landau level of graphene is predicted to show more robust fractional quantum Hall effect than the second Landau level of GaAs.