# Insulators at fractional fillings in twisted bilayer graphene partially aligned to hexagonal boron nitride

https://mdr.nims.go.jp/datasets/d6066e47-a85f-470a-bf11-48dcaeb5e635

## File

- [2024A00124G_VOR_Insualtors at Fractional Fillings... (D.Wong et al) 2023 (submitted PDF).pdf](https://mdr.nims.go.jp/filesets/1b7528c5-46d7-4336-9746-ebf5cb04b226/download) ([Detail](https://mdr.nims.go.jp/filesets/1b7528c5-46d7-4336-9746-ebf5cb04b226.md))

## Id

d6066e47-a85f-470a-bf11-48dcaeb5e635

## Local identifier



## Visibility

open_to_public

## State

published

## Created at

2025-08-01T07:16:34.515195Z

## Updated at

2025-08-01T23:30:34.689000Z

## Published at

2025-08-01T23:17:31.812257Z

## Doi



## First published url

https://doi.org/10.1063/10.0019422

## Date published

2023-06-01

## Recorded date published

2023-6-1

## Resource type

journal_article

## Manuscript type

vor

## Collection



## Title

- title: Insulators at fractional fillings in twisted bilayer graphene partially aligned
    to hexagonal boron nitride
  title_type: original
  lang: en

## Description

- description: At partial fillings of its flat electronic bands, magic-angle twisted
    bilayer graphene (MATBG) hosts a rich variety of competing correlated phases that
    show sample-to-sample variations. Divergent phase diagrams in MATBG are often
    attributed to the sublattice polarization energy scale, tuned by the degree of
    alignment of the hexagonal boron nitride (hBN) substrates typically used in van
    der Waals devices. Unaligned MATBG exhibits unconventional superconductor and
    correlated insulator phases, while nearly perfectly aligned MATBG/hBN exhibits
    zero-field Chern insulating phases and lacks superconductivity. Here we use scanning
    tunneling microscopy and spectroscopy (STM/STS) to observe gapped phases at partial
    fillings of the flat bands of MATBG in a new intermediate regime of sublattice
    polarization, observed when MATBG is only partially aligned (θGr-hBN ≈ 1.65°)
    to the underlying hBN substrate. Under this condition, MATBG hosts not only phenomena
    that naturally interpolate between the two sublattice potential limits, but also
    unexpected gapped phases absent in either of these limits. At charge neutrality,
    we observe an insulating phase with a small energy gap (Δ < 5 meV) likely related
    to weak sublattice symmetry breaking from the hBN substrate. In addition, we observe
    new gapped phases near fractional fillings ν = ±1/3 and ν = ±1/6, which have not
    been previously observed in MATBG. Importantly, energy-resolved STS unambiguously
    identifies these fractional filling states to be of single-particle origin, possibly
    a result of the super-superlattice formed by two moiré superlattices. Our observations
    emphasize the power of STS in distinguishing single-particle gapped phases from
    many-body gapped phases in situations that could be easily confused in electrical
    transport measurements, and demonstrate the use of substrate engineering for modifying
    the electronic structure of a moiré flat-band material.
  description_type: abstract
  lang: en

## Creator

- name: Dillon Wong
  role: author
- name: Kevin P. Nuckolls
  role: author
- name: Myungchul Oh
  role: author
- name: Ryan L. Lee
  role: author
- name: Kenji Watanabe
  role: author
  orcid: https://orcid.org/0000-0003-3701-8119
  organization: National Institute for Materials Science
- name: Takashi Taniguchi
  role: author
  orcid: https://orcid.org/0000-0002-1467-3105
  organization: National Institute for Materials Science
- name: Ali Yazdani
  role: author

## Contact agent



## Publisher

organization: AIP Publishing

## Managing organization



## Keyword

- subject: Magic-angle twisted bilayer graphene
  schema: not_defined
- subject: Sublattice polarization
  schema: not_defined
- subject: Gapped phases at fractional fillings
  schema: not_defined

## Rights

- description: 'This article may be downloaded for personal use only. Any other use
    requires prior permission of the author and AIP Publishing. This article appeared
    in Dillon Wong, Kevin P. Nuckolls, Myungchul Oh, Ryan L. Lee, Kenji Watanabe,
    Takashi Taniguchi, Ali Yazdani; Insulators at fractional fillings in twisted bilayer
    graphene partially aligned to hexagonal boron nitride. Low Temp. Phys. 1 June
    2023; 49 (6): 655–661 and may be found at https://doi.org/10.1063/10.0019422.'
  identifier: http://rightsstatements.org/vocab/InC/1.0/

## Other identifier(s)



## Data origin

- data_origin_type: other

## Embargo

start_date: 2023-06-01
end_date: 2024-06-01

## Journal

- title: Low Temperature Physics
  issn: 1063777X
  volume: '49'
  issue: '6'
  start_page: 655
  end_page: 661

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## Measurement method



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## Fileset

- id: 1b7528c5-46d7-4336-9746-ebf5cb04b226
  filename: 2024A00124G_VOR_Insualtors at Fractional Fillings... (D.Wong et al) 2023
    (submitted PDF).pdf
  content_type: application/pdf
  size: 4640518
  md5: 4fab997c0176e2127a858eb1821d8d9e

## Thumbnail

fileset_id: 1b7528c5-46d7-4336-9746-ebf5cb04b226
filename: 2024A00124G_VOR_Insualtors at Fractional Fillings... (D.Wong et al) 2023
  (submitted PDF).pdf