# Ultrafast pseudospin quantum beats in multilayer WSe2 and MoSe2

https://mdr.nims.go.jp/datasets/69a69206-79f8-4737-989a-c49228f84c2c

## File

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## Id

69a69206-79f8-4737-989a-c49228f84c2c

## Local identifier



## Visibility

open_to_public

## State

published

## Created at

2025-02-26T02:57:51.598948Z

## Updated at

2025-02-26T23:30:39.850663Z

## Published at

2025-02-26T23:30:39.993547Z

## Doi



## First published url

https://doi.org/10.1038/s41467-022-32534-3

## Date published

2022-08-25

## Recorded date published



## Resource type

journal_article

## Manuscript type

vor

## Collection



## Title

- title: Ultrafast pseudospin quantum beats in multilayer WSe2 and MoSe2
  title_type: original
  lang: en

## Description

- description: Layered van-der-Waals materials with hexagonal symmetry offer an extra
    degree of freedom to their electrons, the so called valley index or valley pseudospin.
    This quantity behaves conceptually like the electron spin and the term valleytronics
    has been coined. In this context, the group of semiconducting transition-metal
    dichalcogenides (TMDC) are particularly appealing, due to large spin-orbit interactions
    and a direct bandgap at the K points of the hexagonal Brillouin zone. In this
    work, we present investigations of excitonic transitions in mono- and multilayer
    WSe2 and MoSe2 materials by time-resolved Faraday ellipticity (TRFE) with in-plane
    magnetic fields, B//, of up to 9 T. In monolayer samples, the measured TRFE time
    traces are almost independent of B∥, which confirms a close to zero in-plane exciton
    g factor g//, consistent with first-principles calculations. In stark contrast,
    we observe pronounced temporal oscillations in multilayer samples for B// > 0.
    Remarkably, the extracted in-plane g∥ are very close to reported out-of-plane
    exciton g factors of the materials, namely |g//1s| = 3.1 ± 0.2 and 2.5 ± 0.2 for
    the 1s A excitons in WSe2 and MoSe2 multilayers, respectively. Our first-principles
    calculations nicely confirm the presence of a non-zero g∥ for the multilayer samples.
    We propose that the oscillatory TRFE signal in the multilayer samples is caused
    by pseudospin quantum beats of excitons, which is a manifestation of spin- and
    pseudospin layer locking in the multilayer samples. Our results demonstrate ultrafast
    pseudospin rotations in the GHz- to THz frequency range, which pave the way towards
    ultrafast pseudospin manipulation in multilayer TMDC samples.
  description_type: abstract
  lang: und

## Creator

- name: Simon Raiber
  role: author
- name: Paulo E. Faria Junior
  role: author
- name: Dennis Falter
  role: author
- name: Simon Feldl
  role: author
- name: Petter Marzena
  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: Jaroslav Fabian
  role: author
- name: Christian Schüller
  role: author

## Contact agent



## Publisher

organization: Springer Science and Business Media LLC

## Managing organization



## Keyword

- subject: Valley index
  schema: not_defined
- subject: excitonic transitions
  schema: not_defined
- subject: pseudospin quantum beats
  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: '4997'

## Conference



## Related item



## Funding

- identifier: '314695032'
  funder_name: Deutsche Forschungsgemeinschaft
- identifier: SCHU1171/10-1
  funder_name: Deutsche Forschungsgemeinschaft

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## Fileset

- id: 520e3b29-265b-4e70-9e5b-62cec81a2e08
  filename: s41467-022-32534-3.pdf
  content_type: application/pdf
  size: 1395245
  md5: 363435fe7c18b95e23d06cd97da4d3a2

## Thumbnail

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filename: s41467-022-32534-3.pdf