# Perpendicular electric field drives Chern transitions and layer polarization changes in Hofstadter bands

https://mdr.nims.go.jp/datasets/87e08a94-f12e-4c9b-abed-114ce014501e

## File

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## Id

87e08a94-f12e-4c9b-abed-114ce014501e

## Local identifier



## Visibility

open_to_public

## State

published

## Created at

2025-02-26T06:33:25.147213Z

## Updated at

2025-02-27T03:30:39.449664Z

## Published at

2025-02-27T03:30:39.550636Z

## Doi



## First published url

https://doi.org/10.1038/s41467-022-35421-z

## Date published

2022-12-16

## Recorded date published



## Resource type

journal_article

## Manuscript type

vor

## Collection



## Title

- title: Perpendicular electric field drives Chern transitions and layer polarization
    changes in Hofstadter bands
  title_type: original
  lang: en

## Description

- description: Moiré superlattices engineer band properties and enable observation
    of fractal energy spectra of Hofstadter butterfly. Specifically, small-angle moiré
    results in flat bands due to strong hybridization between layers. To date, the
    major focus has been to gain new insights into correlated-electron physics hosted
    by the flat bands. However, the implications of the topology of these moiré bands
    within the framework of single-particle physics are little explored experimentally.
    An outstanding problem is to understand the effect of band topology on Hofstadter
    physics, which does not require electron correlations. In this work, we use a
    tunable topological band platform, namely twisted double bilayer graphene (TDBG),
    to experimentally study Chern state switching in the Hofstadter regime. In TDBG,
    unlike in TBG, the perpendicular electric field can tune the band structure as
    well as its topological properties like valley Chern numbers. We show that the
    nontrivial topology reflects in the Hofstadter spectra, in particular, displaying
    a cascade of Hofstadter gaps that switch their Chern numbers one-at-a-time as
    we vary the electric field. Our experiments together with theoretical calculations
    suggest a crucial role of charge polarization in this system that changes concomitantly
    with topological transitions. The layer polarization is likely to play an important
    role in the topological states in few-layer twisted systems. Moreover, our work
    establishes TDBG as a novel Hofstadter platform with nontrivial magnetoelectric
    coupling.
  description_type: abstract
  lang: und

## Creator

- name: Pratap Chandra Adak
  role: author
- name: Subhajit Sinha
  role: author
- name: Debasmita Giri
  role: author
- name: Dibya Kanti Mukherjee
  role: author
- name: Chandan
  role: author
- name: L. D. Varma Sangani
  role: author
- name: Surat Layek
  role: author
- name: Ayshi Mukherjee
  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: H. A. Fertig
  role: author
- name: Arijit Kundu
  role: author
- name: Mandar M. Deshmukh
  role: author

## Contact agent



## Publisher

organization: Springer Science and Business Media LLC

## Managing organization



## Keyword

- subject: Moiré superlattices
  schema: not_defined
- subject: Hofstadter butterfly
  schema: not_defined
- subject: Chern state
  schema: not_defined

## Rights

- identifier: https://creativecommons.org/licenses/by/4.0/

## Other identifier(s)



## Data origin



## Embargo



## Journal

- title: Nature Communications
  issn: '20411723'
  volume: '13'
  issue: '1'
  article_number: '7781'

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## Specimen



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## Fileset

- id: b0530625-e3f2-4c46-95df-77fae2a3b044
  filename: s41467-022-35421-z.pdf
  content_type: application/pdf
  size: 2903525
  md5: 9e2210618e5f57dc61b922f120d06170

## Thumbnail

fileset_id: b0530625-e3f2-4c46-95df-77fae2a3b044
filename: s41467-022-35421-z.pdf