Intralayer charge-transfer moiré excitons in van der Waals superlattices

Mit H. Naik, Emma C. Regan, Zuocheng Zhang, Yang Hao Chan, Zhenglu Li, Danqing Wang, Yoseob Yoon, Chin Shen Ong, Wenyu Zhao, Sihan Zhao, M. Iqbal Bakti Utama, Beini Gao, Xin Wei, Mohammed Sayyad, Kentaro Yumigeta, Kenji Watanabe, Takashi Taniguchi, Sefaattin Tongay, Felipe H. da Jornada, Feng WangSteven G. Louie

Research output: Contribution to journalArticlepeer-review

Abstract

Moiré patterns of transition metal dichalcogenide heterobilayers have proved to be an ideal platform on which to host unusual correlated electronic phases, emerging magnetism and correlated exciton physics. Whereas the existence of new moiré excitonic states is established1–4 through optical measurements, the microscopic nature of these states is still poorly understood, often relying on empirically fit models. Here, combining large-scale first-principles GW (where G and W denote the one-particle Green's function and the screened Coulomb interaction, respectively) plus Bethe–Salpeter calculations and micro-reflection spectroscopy, we identify the nature of the exciton resonances in WSe2/WS2 moiré superlattices, discovering a rich set of moiré excitons that cannot be captured by prevailing continuum models. Our calculations show moiré excitons with distinct characters, including modulated Wannier excitons and previously unidentified intralayer charge-transfer excitons. Signatures of these distinct excitonic characters are confirmed experimentally by the unique carrier-density and magnetic-field dependences of different moiré exciton resonances. Our study highlights the highly non-trivial exciton states that can emerge in transition metal dichalcogenide moiré superlattices, and suggests new ways of tuning many-body physics in moiré systems by engineering excited-states with specific spatial characters.

Original languageEnglish (US)
Pages (from-to)52-57
Number of pages6
JournalNature
Volume609
Issue number7925
DOIs
StatePublished - Sep 1 2022

ASJC Scopus subject areas

  • General

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