### Abstract

An important development in the field of the fractional quantum Hall effect was the proposal that the 5/2 state observed in the Landau level with orbital index n = 1 of two-dimensional electrons in a GaAs quantum well ^{1} originates from a chiral p-wave paired state of composite fermions that are topological bound states of electrons and quantized vortices. The excitations of this state, which is theoretically described by a ‘Pfaffian’ wavefunction ^{2} or its hole partner called the anti-Pfaffian ^{3,4} , are neither fermions nor bosons but Majorana quasiparticles obeying non-Abelian braid statistics ^{5} . This has inspired ideas for fault-tolerant topological quantum computation ^{6} and has also instigated a search for other states with exotic quasiparticles. Here we report experiments on monolayer graphene that show clear evidence for unexpected even denominator fractional quantum Hall physics in the n = 3 Landau level. We numerically investigate the known candidate states for the even denominator fractional quantum Hall effect, including the Pfaffian, the particle–hole symmetric Pfaffian and the 221-parton states, and conclude that, among these, the 221-parton appears a potentially suitable candidate to describe the experimentally observed state. Like the Pfaffian, this state is believed to harbour quasi-particles with non-Abelian braid statistics ^{7} .

Original language | English (US) |
---|---|

Pages (from-to) | 154-158 |

Number of pages | 5 |

Journal | Nature Physics |

Volume | 15 |

Issue number | 2 |

DOIs | |

State | Published - Feb 1 2019 |

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### All Science Journal Classification (ASJC) codes

- Physics and Astronomy(all)

### Cite this

*Nature Physics*,

*15*(2), 154-158. https://doi.org/10.1038/s41567-018-0355-x

}

*Nature Physics*, vol. 15, no. 2, pp. 154-158. https://doi.org/10.1038/s41567-018-0355-x

**Even denominator fractional quantum Hall states in higher Landau levels of graphene.** / Kim, Youngwook; Balram, Ajit C.; Taniguchi, Takashi; Watanabe, Kenji; Jain, Jainendra K.; Smet, Jurgen H.

Research output: Contribution to journal › Letter

TY - JOUR

T1 - Even denominator fractional quantum Hall states in higher Landau levels of graphene

AU - Kim, Youngwook

AU - Balram, Ajit C.

AU - Taniguchi, Takashi

AU - Watanabe, Kenji

AU - Jain, Jainendra K.

AU - Smet, Jurgen H.

PY - 2019/2/1

Y1 - 2019/2/1

N2 - An important development in the field of the fractional quantum Hall effect was the proposal that the 5/2 state observed in the Landau level with orbital index n = 1 of two-dimensional electrons in a GaAs quantum well 1 originates from a chiral p-wave paired state of composite fermions that are topological bound states of electrons and quantized vortices. The excitations of this state, which is theoretically described by a ‘Pfaffian’ wavefunction 2 or its hole partner called the anti-Pfaffian 3,4 , are neither fermions nor bosons but Majorana quasiparticles obeying non-Abelian braid statistics 5 . This has inspired ideas for fault-tolerant topological quantum computation 6 and has also instigated a search for other states with exotic quasiparticles. Here we report experiments on monolayer graphene that show clear evidence for unexpected even denominator fractional quantum Hall physics in the n = 3 Landau level. We numerically investigate the known candidate states for the even denominator fractional quantum Hall effect, including the Pfaffian, the particle–hole symmetric Pfaffian and the 221-parton states, and conclude that, among these, the 221-parton appears a potentially suitable candidate to describe the experimentally observed state. Like the Pfaffian, this state is believed to harbour quasi-particles with non-Abelian braid statistics 7 .

AB - An important development in the field of the fractional quantum Hall effect was the proposal that the 5/2 state observed in the Landau level with orbital index n = 1 of two-dimensional electrons in a GaAs quantum well 1 originates from a chiral p-wave paired state of composite fermions that are topological bound states of electrons and quantized vortices. The excitations of this state, which is theoretically described by a ‘Pfaffian’ wavefunction 2 or its hole partner called the anti-Pfaffian 3,4 , are neither fermions nor bosons but Majorana quasiparticles obeying non-Abelian braid statistics 5 . This has inspired ideas for fault-tolerant topological quantum computation 6 and has also instigated a search for other states with exotic quasiparticles. Here we report experiments on monolayer graphene that show clear evidence for unexpected even denominator fractional quantum Hall physics in the n = 3 Landau level. We numerically investigate the known candidate states for the even denominator fractional quantum Hall effect, including the Pfaffian, the particle–hole symmetric Pfaffian and the 221-parton states, and conclude that, among these, the 221-parton appears a potentially suitable candidate to describe the experimentally observed state. Like the Pfaffian, this state is believed to harbour quasi-particles with non-Abelian braid statistics 7 .

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U2 - 10.1038/s41567-018-0355-x

DO - 10.1038/s41567-018-0355-x

M3 - Letter

AN - SCOPUS:85057494325

VL - 15

SP - 154

EP - 158

JO - Nature Physics

JF - Nature Physics

SN - 1745-2473

IS - 2

ER -