Hybridized intervalley moiré excitons and flat bands in twisted WSe2 bilayers

Brem, Samuel; Lin, Kai-Qiang; Gillen, Roland; Bauer, Jonas M.; Maultzsch, Janina; Lupton, John M.; Malic, Ermin

doi:10.1039/d0nr02160a

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Hybridized intervalley moiré excitons and flat bands in twisted WSe2 bilayers

Samuel Brem

, Kai-Qiang Lin

, Roland Gillen

, Jonas M. Bauer, Janina Maultzsch, John M. Lupton, Ermin Malic

Nanoscale, Volume: 12, Issue: 20, Pages: 11088 - 11094

Swansea University Author: Roland Gillen

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DOI (Published version): 10.1039/d0nr02160a

Abstract

The large surface-to-volume ratio in atomically thin 2D materials allows to efficiently tune their properties through modifications of their environment. Artificial stacking of two monolayers into a bilayer leads to an overlap of layer-localized wave functions giving rise to a twist angle-dependent...

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Published in:	Nanoscale
ISSN:	2040-3364 2040-3372
Published:	Royal Society of Chemistry (RSC) 2020
Online Access:	Check full text
URI:	https://cronfa.swan.ac.uk/Record/cronfa66659

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spelling	2024-08-13T17:01:31.2570133 v2 66659 2024-06-11 Hybridized intervalley moiré excitons and flat bands in twisted WSe2 bilayers 8fd99815709ad1e4ae52e27f63257604 0000-0002-7913-0953 Roland Gillen Roland Gillen true false 2024-06-11 ACEM The large surface-to-volume ratio in atomically thin 2D materials allows to efficiently tune their properties through modifications of their environment. Artificial stacking of two monolayers into a bilayer leads to an overlap of layer-localized wave functions giving rise to a twist angle-dependent hybridization of excitonic states. In this joint theory-experiment study, we demonstrate the impact of interlayer hybridization on bright and momentum-dark excitons in twisted WSe2 bilayers. In particular, we show that the strong hybridization of electrons at the Λ point leads to a drastic redshift of the momentum-dark K–Λ exciton, accompanied by the emergence of flat moiré exciton bands at small twist angles. We directly compare theoretically predicted and experimentally measured optical spectra allowing us to identify photoluminescence signals stemming from phonon-assisted recombination of layer-hybridized dark excitons. Moreover, we predict the emergence of additional spectral features resulting from the moiré potential of the twisted bilayer lattice. Journal Article Nanoscale 12 20 11088 11094 Royal Society of Chemistry (RSC) 2040-3364 2040-3372 13 5 2020 2020-05-13 10.1039/d0nr02160a COLLEGE NANME Aerospace, Civil, Electrical, and Mechanical Engineering COLLEGE CODE ACEM Swansea University Another institution paid the OA fee The Chalmers group acknowledges financial support from the European Unions Horizon 2020 research and innovation program under grant agreement no 785219 (Graphene Flagship) as well as from the Swedish Research Council (VR, project number 2018-00734). The Regensburg group acknowledges financial support from Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – Project-ID 314695032 – SFB 1277 project B03. The Erlangen group acknowledges the Regional Computer Centre Erlangen (RRZE) for providing the computational resources for the DFT simulations. 2024-08-13T17:01:31.2570133 2024-06-11T12:46:50.5761851 Faculty of Science and Engineering School of Aerospace, Civil, Electrical, General and Mechanical Engineering - Electronic and Electrical Engineering Samuel Brem 0000-0001-8823-1302 1 Kai-Qiang Lin 0000-0001-9609-749x 2 Roland Gillen 0000-0002-7913-0953 3 Jonas M. Bauer 4 Janina Maultzsch 5 John M. Lupton 6 Ermin Malic 7 66659__31102__d80cfd7462fd46dbafd99f6907b4d49a.pdf 66659.VoR.pdf 2024-08-13T16:59:38.5540012 Output 1909590 application/pdf Version of Record true Released under the terms of a Creative Commons Attribution-NonCommercial 3.0 Unported Licence. true eng http://creativecommons.org/licenses/by-nc/3.0/
title	Hybridized intervalley moiré excitons and flat bands in twisted WSe2 bilayers
spellingShingle	Hybridized intervalley moiré excitons and flat bands in twisted WSe2 bilayers Roland Gillen
title_short	Hybridized intervalley moiré excitons and flat bands in twisted WSe2 bilayers
title_full	Hybridized intervalley moiré excitons and flat bands in twisted WSe2 bilayers
title_fullStr	Hybridized intervalley moiré excitons and flat bands in twisted WSe2 bilayers
title_full_unstemmed	Hybridized intervalley moiré excitons and flat bands in twisted WSe2 bilayers
title_sort	Hybridized intervalley moiré excitons and flat bands in twisted WSe2 bilayers
author_id_str_mv	8fd99815709ad1e4ae52e27f63257604
author_id_fullname_str_mv	8fd99815709ad1e4ae52e27f63257604_***_Roland Gillen
author	Roland Gillen
author2	Samuel Brem Kai-Qiang Lin Roland Gillen Jonas M. Bauer Janina Maultzsch John M. Lupton Ermin Malic
format	Journal article
container_title	Nanoscale
container_volume	12
container_issue	20
container_start_page	11088
publishDate	2020
institution	Swansea University
issn	2040-3364 2040-3372
doi_str_mv	10.1039/d0nr02160a
publisher	Royal Society of Chemistry (RSC)
college_str	Faculty of Science and Engineering
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hierarchy_top_title	Faculty of Science and Engineering
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hierarchy_parent_title	Faculty of Science and Engineering
department_str	School of Aerospace, Civil, Electrical, General and Mechanical Engineering - Electronic and Electrical Engineering{{{_:::_}}}Faculty of Science and Engineering{{{_:::_}}}School of Aerospace, Civil, Electrical, General and Mechanical Engineering - Electronic and Electrical Engineering
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description	The large surface-to-volume ratio in atomically thin 2D materials allows to efficiently tune their properties through modifications of their environment. Artificial stacking of two monolayers into a bilayer leads to an overlap of layer-localized wave functions giving rise to a twist angle-dependent hybridization of excitonic states. In this joint theory-experiment study, we demonstrate the impact of interlayer hybridization on bright and momentum-dark excitons in twisted WSe2 bilayers. In particular, we show that the strong hybridization of electrons at the Λ point leads to a drastic redshift of the momentum-dark K–Λ exciton, accompanied by the emergence of flat moiré exciton bands at small twist angles. We directly compare theoretically predicted and experimentally measured optical spectra allowing us to identify photoluminescence signals stemming from phonon-assisted recombination of layer-hybridized dark excitons. Moreover, we predict the emergence of additional spectral features resulting from the moiré potential of the twisted bilayer lattice.
published_date	2020-05-13T08:25:35Z
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score	11.094046

Hybridized intervalley moiré excitons and flat bands in twisted WSe2 bilayers

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