Chern Insulators at Integer and Fractional Filling in Moiré Pentalayer Graphene

The advent of moiré platforms for engineered quantum matter has led to discoveries of integer and fractional quantum anomalous Hall effects, with predictions for correlation-driven topological states based on electron crystallization. Here, we report an array of trivial and topological insulators fo...

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Main Authors: Dacen Waters, Anna Okounkova, Ruiheng Su, Boran Zhou, Jiang Yao, Kenji Watanabe, Takashi Taniguchi, Xiaodong Xu, Ya-Hui Zhang, Joshua Folk, Matthew Yankowitz
Format: Article
Language:English
Published: American Physical Society 2025-02-01
Series:Physical Review X
Online Access:http://doi.org/10.1103/PhysRevX.15.011045
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author Dacen Waters
Anna Okounkova
Ruiheng Su
Boran Zhou
Jiang Yao
Kenji Watanabe
Takashi Taniguchi
Xiaodong Xu
Ya-Hui Zhang
Joshua Folk
Matthew Yankowitz
author_facet Dacen Waters
Anna Okounkova
Ruiheng Su
Boran Zhou
Jiang Yao
Kenji Watanabe
Takashi Taniguchi
Xiaodong Xu
Ya-Hui Zhang
Joshua Folk
Matthew Yankowitz
author_sort Dacen Waters
collection DOAJ
description The advent of moiré platforms for engineered quantum matter has led to discoveries of integer and fractional quantum anomalous Hall effects, with predictions for correlation-driven topological states based on electron crystallization. Here, we report an array of trivial and topological insulators formed in a moiré lattice of rhomobohedral pentalayer graphene (R5G). At a doping of one electron per moiré unit cell (ν=1), we see a correlated insulator with a Chern number that can be tuned between C=0 and +1 by an electric displacement field. This is accompanied by a series of additional Chern insulators with C=+1 originating from fractional fillings of the moiré lattice—ν=1/4, 1/3, and 2/3—associated with the formation of moiré-driven topological electronic crystals. At ν=2/3 the system exhibits an integer quantum anomalous Hall effect at zero magnetic field, but further develops hints of an incipient C=2/3 fractional Chern insulator in a modest field. Our results establish moiré R5G as a fertile platform for studying the competition and potential intertwining of integer and fractional Chern insulators.
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spelling doaj-art-7990bf89cea447df807745fabbd5561a2025-08-20T02:04:21ZengAmerican Physical SocietyPhysical Review X2160-33082025-02-0115101104510.1103/PhysRevX.15.011045Chern Insulators at Integer and Fractional Filling in Moiré Pentalayer GrapheneDacen WatersAnna OkounkovaRuiheng SuBoran ZhouJiang YaoKenji WatanabeTakashi TaniguchiXiaodong XuYa-Hui ZhangJoshua FolkMatthew YankowitzThe advent of moiré platforms for engineered quantum matter has led to discoveries of integer and fractional quantum anomalous Hall effects, with predictions for correlation-driven topological states based on electron crystallization. Here, we report an array of trivial and topological insulators formed in a moiré lattice of rhomobohedral pentalayer graphene (R5G). At a doping of one electron per moiré unit cell (ν=1), we see a correlated insulator with a Chern number that can be tuned between C=0 and +1 by an electric displacement field. This is accompanied by a series of additional Chern insulators with C=+1 originating from fractional fillings of the moiré lattice—ν=1/4, 1/3, and 2/3—associated with the formation of moiré-driven topological electronic crystals. At ν=2/3 the system exhibits an integer quantum anomalous Hall effect at zero magnetic field, but further develops hints of an incipient C=2/3 fractional Chern insulator in a modest field. Our results establish moiré R5G as a fertile platform for studying the competition and potential intertwining of integer and fractional Chern insulators.http://doi.org/10.1103/PhysRevX.15.011045
spellingShingle Dacen Waters
Anna Okounkova
Ruiheng Su
Boran Zhou
Jiang Yao
Kenji Watanabe
Takashi Taniguchi
Xiaodong Xu
Ya-Hui Zhang
Joshua Folk
Matthew Yankowitz
Chern Insulators at Integer and Fractional Filling in Moiré Pentalayer Graphene
Physical Review X
title Chern Insulators at Integer and Fractional Filling in Moiré Pentalayer Graphene
title_full Chern Insulators at Integer and Fractional Filling in Moiré Pentalayer Graphene
title_fullStr Chern Insulators at Integer and Fractional Filling in Moiré Pentalayer Graphene
title_full_unstemmed Chern Insulators at Integer and Fractional Filling in Moiré Pentalayer Graphene
title_short Chern Insulators at Integer and Fractional Filling in Moiré Pentalayer Graphene
title_sort chern insulators at integer and fractional filling in moire pentalayer graphene
url http://doi.org/10.1103/PhysRevX.15.011045
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