Rydberg series of intralayer K-excitons in WSe$_2$ multilayers

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Hauptverfasser: Kapuscinski, Piotr, Slobodeniuk, Artur O., Delhomme, Alex, Faugeras, Clément, Grzeszczyk, Magdalena, Nogajewski, Karol, Watanabe, Kenji, Taniguchi, Takashi, Potemski, Marek
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Veröffentlicht: 2024
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author Kapuscinski, Piotr
Slobodeniuk, Artur O.
Delhomme, Alex
Faugeras, Clément
Grzeszczyk, Magdalena
Nogajewski, Karol
Watanabe, Kenji
Taniguchi, Takashi
Potemski, Marek
author_facet Kapuscinski, Piotr
Slobodeniuk, Artur O.
Delhomme, Alex
Faugeras, Clément
Grzeszczyk, Magdalena
Nogajewski, Karol
Watanabe, Kenji
Taniguchi, Takashi
Potemski, Marek
contents Semiconducting transition metal dichalcogenides of group VI are well-known for their prominent excitonic effects and the transition from an indirect to a direct band gap when reduced to monolayers. While considerable efforts have elucidated the Rydberg series of excitons in monolayers, understanding their properties in multilayers remains incomplete. In these structures, despite an indirect band gap, momentum-direct excitons largely shape the optical response. In this work, we combine magneto-reflectance experiments with theoretical modeling based on the $\mathbf {k\cdot p}$ approach to investigate the origin of excitonic resonances in WSe$_2$ bi-, tri-, and quadlayers. For all investigated thicknesses, we observe a series of excitonic resonances in the reflectance spectra, initiated by a ground state with an amplitude comparable to the ground state of the 1$s$ exciton in the monolayer. Higher energy states exhibit a decrease in intensity with increasing energy, as expected for the excited states of the Rydberg series, although a significant increase in the diamagnetic shift is missing in tri- and quadlayers. By comparing the experimental observations with theoretical predictions, we discover that the excitonic resonances observed in trilayers originate from two Rydberg series, while quadlayers exhibit four such series, and bilayers host a single Rydberg series similar to that found in monolayers.
format Preprint
id arxiv_https___arxiv_org_abs_2411_02241
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Rydberg series of intralayer K-excitons in WSe$_2$ multilayers
Kapuscinski, Piotr
Slobodeniuk, Artur O.
Delhomme, Alex
Faugeras, Clément
Grzeszczyk, Magdalena
Nogajewski, Karol
Watanabe, Kenji
Taniguchi, Takashi
Potemski, Marek
Mesoscale and Nanoscale Physics
Optics
Semiconducting transition metal dichalcogenides of group VI are well-known for their prominent excitonic effects and the transition from an indirect to a direct band gap when reduced to monolayers. While considerable efforts have elucidated the Rydberg series of excitons in monolayers, understanding their properties in multilayers remains incomplete. In these structures, despite an indirect band gap, momentum-direct excitons largely shape the optical response. In this work, we combine magneto-reflectance experiments with theoretical modeling based on the $\mathbf {k\cdot p}$ approach to investigate the origin of excitonic resonances in WSe$_2$ bi-, tri-, and quadlayers. For all investigated thicknesses, we observe a series of excitonic resonances in the reflectance spectra, initiated by a ground state with an amplitude comparable to the ground state of the 1$s$ exciton in the monolayer. Higher energy states exhibit a decrease in intensity with increasing energy, as expected for the excited states of the Rydberg series, although a significant increase in the diamagnetic shift is missing in tri- and quadlayers. By comparing the experimental observations with theoretical predictions, we discover that the excitonic resonances observed in trilayers originate from two Rydberg series, while quadlayers exhibit four such series, and bilayers host a single Rydberg series similar to that found in monolayers.
title Rydberg series of intralayer K-excitons in WSe$_2$ multilayers
topic Mesoscale and Nanoscale Physics
Optics
url https://arxiv.org/abs/2411.02241