Article Odd-even layer-number effect of valence-band spin splitting in WTe2

Masato Sakano ; Yuma Tanaka ; Satoru Masubuchi ; Shota Okazaki ; Takuya Nomoto ; Atsushi Oshima ; Kenji Watanabe SAMURAI ORCID (National Institute for Materials Science) ; Takashi Taniguchi SAMURAI ORCID (National Institute for Materials Science) ; Ryotaro Arita ; Takao Sasagawa ; Tomoki Machida ; Kyoko Ishizaka

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Masato Sakano, Yuma Tanaka, Satoru Masubuchi, Shota Okazaki, Takuya Nomoto, Atsushi Oshima, Kenji Watanabe, Takashi Taniguchi, Ryotaro Arita, Takao Sasagawa, Tomoki Machida, Kyoko Ishizaka. Odd-even layer-number effect of valence-band spin splitting in WTe2. Physical Review Research. 2022, 4 (2), 023247.
SAMURAI

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(abstract)

When a crystal becomes thinner and thinner to the atomic level, peculiar phenomena discretely depending on its layer-numbers (n) start to appear. The symmetry and wave functions strongly reflect the layer-numbers and stacking order, which brings us a potential of realizing new properties and functions that is unexpected in either bulk or simple monolayer. Multilayer WTe2 is one such example exhibiting unique ferroelectricity and non-linear transport properties related to the antiphase stacking and Berry-curvature dipole. Here we investigate the electronic band dispersions of multilayer WTe2 (2-5 layers), by performing laser-based micro-focused angle-resolved photoelectron spectroscopy on exfoliated-flakes that are strictly sorted by n and encapsulated by graphene. We clearly observed the insulator-semimetal transition occurring between 2 and 3-layers, as well as the 30-70 meV spin-splitting of valence bands manifesting in even n as a signature of stronger structural asymmetry. Our result fully demonstrates the possibility of the large energy-scale band and spin manipulation through the finite n stacking procedure.

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Keyword: WTe2, valence bands, spin splitting

Date published: 2022-06-27

Publisher: American Physical Society (APS)

Journal:

  • Physical Review Research (ISSN: 26431564) vol. 4 issue. 2 023247

Funding:

  • Core Research for Evolutional Science and Technology JPMJCR15F3
  • Core Research for Evolutional Science and Technology JPMJCR16F2
  • Core Research for Evolutional Science and Technology JPMJCR20B4
  • Japan Society for the Promotion of Science JP20H00127
  • Japan Society for the Promotion of Science JP20H00354
  • Japan Society for the Promotion of Science JP20H01834
  • Japan Society for the Promotion of Science JP21H05232
  • Japan Society for the Promotion of Science JP21H05233
  • Japan Society for the Promotion of Science JP21H05234
  • Japan Society for the Promotion of Science JP21H05235
  • Japan Society for the Promotion of Science JP21H05236
  • Japan Science and Technology Agency

Manuscript type: Publisher's version (Version of record)

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First published URL: https://doi.org/10.1103/physrevresearch.4.023247

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Updated at: 2025-02-28 12:30:18 +0900

Published on MDR: 2025-02-28 12:30:18 +0900

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