Resonance Raman enhancement by the intralayer and interlayer electron–phonon processes in twisted bilayer graphene

Abstract Twisted bilayer graphene is a fascinating system due to the possibility of tuning the electronic and optical properties by controlling the twisting angle $$\theta$$ θ between the layers. The coupling between the Dirac cones of the two graphene layers gives rise to van Hove singularities (vH...

Descripción completa

Guardado en:

Detalles Bibliográficos
Autores principales:	M. V. O. Moutinho, G. S. N. Eliel, A. Righi, R. N. Gontijo, M. Paillet, T. Michel, Po-Wen Chiu, P. Venezuela, M. A. Pimenta
Formato:	article
Lenguaje:	EN
Publicado:	Nature Portfolio 2021
Materias:	Medicine R Science Q
Acceso en línea:	https://doaj.org/article/a43e16afd12945f5a733daefe6ccb552
Etiquetas:	Agregar Etiqueta Sin Etiquetas, Sea el primero en etiquetar este registro!

id	oai:doaj.org-article:a43e16afd12945f5a733daefe6ccb552
record_format	dspace
spelling	oai:doaj.org-article:a43e16afd12945f5a733daefe6ccb5522021-12-02T18:53:08ZResonance Raman enhancement by the intralayer and interlayer electron–phonon processes in twisted bilayer graphene10.1038/s41598-021-96515-02045-2322https://doaj.org/article/a43e16afd12945f5a733daefe6ccb5522021-08-01T00:00:00Zhttps://doi.org/10.1038/s41598-021-96515-0https://doaj.org/toc/2045-2322Abstract Twisted bilayer graphene is a fascinating system due to the possibility of tuning the electronic and optical properties by controlling the twisting angle $$\theta$$ θ between the layers. The coupling between the Dirac cones of the two graphene layers gives rise to van Hove singularities (vHs) in the density of electronic states, whose energies vary with $$\theta$$ θ . Raman spectroscopy is a fundamental tool to study twisted bilayer graphene (TBG) systems since the Raman response is hugely enhanced when the photons are in resonance with transition between vHs and new peaks appear in the Raman spectra due to phonons within the interior of the Brillouin zone of graphene that are activated by the Moiré superlattice. It was recently shown that these new peaks can be activated by the intralayer and the interlayer electron–phonon processes. In this work we study how each one of these processes enhances the intensities of the peaks coming from the acoustic and optical phonon branches of graphene. Resonance Raman measurements, performed in many different TBG samples with $$\theta$$ θ between $$4^{\circ }$$ 4 ∘ and $$16^{\circ }$$ 16 ∘ and using several different laser excitation energies in the near-infrared (NIR) and visible ranges (1.39–2.71 eV), reveal the distinct enhancement of the different phonons of graphene by the intralayer and interlayer processes. Experimental results are nicely explained by theoretical calculations of the double-resonance Raman intensity in graphene by imposing the momentum conservation rules for the intralayer and the interlayer electron–phonon resonant conditions in TBGs. Our results show that the resonant enhancement of the Raman response in all cases is affected by the quantum interference effect and the symmetry requirements of the double resonance Raman process in graphene.M. V. O. MoutinhoG. S. N. ElielA. RighiR. N. GontijoM. PailletT. MichelPo-Wen ChiuP. VenezuelaM. A. PimentaNature PortfolioarticleMedicineRScienceQENScientific Reports, Vol 11, Iss 1, Pp 1-9 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	Medicine R Science Q
spellingShingle	Medicine R Science Q M. V. O. Moutinho G. S. N. Eliel A. Righi R. N. Gontijo M. Paillet T. Michel Po-Wen Chiu P. Venezuela M. A. Pimenta Resonance Raman enhancement by the intralayer and interlayer electron–phonon processes in twisted bilayer graphene
description	Abstract Twisted bilayer graphene is a fascinating system due to the possibility of tuning the electronic and optical properties by controlling the twisting angle $$\theta$$ θ between the layers. The coupling between the Dirac cones of the two graphene layers gives rise to van Hove singularities (vHs) in the density of electronic states, whose energies vary with $$\theta$$ θ . Raman spectroscopy is a fundamental tool to study twisted bilayer graphene (TBG) systems since the Raman response is hugely enhanced when the photons are in resonance with transition between vHs and new peaks appear in the Raman spectra due to phonons within the interior of the Brillouin zone of graphene that are activated by the Moiré superlattice. It was recently shown that these new peaks can be activated by the intralayer and the interlayer electron–phonon processes. In this work we study how each one of these processes enhances the intensities of the peaks coming from the acoustic and optical phonon branches of graphene. Resonance Raman measurements, performed in many different TBG samples with $$\theta$$ θ between $$4^{\circ }$$ 4 ∘ and $$16^{\circ }$$ 16 ∘ and using several different laser excitation energies in the near-infrared (NIR) and visible ranges (1.39–2.71 eV), reveal the distinct enhancement of the different phonons of graphene by the intralayer and interlayer processes. Experimental results are nicely explained by theoretical calculations of the double-resonance Raman intensity in graphene by imposing the momentum conservation rules for the intralayer and the interlayer electron–phonon resonant conditions in TBGs. Our results show that the resonant enhancement of the Raman response in all cases is affected by the quantum interference effect and the symmetry requirements of the double resonance Raman process in graphene.
format	article
author	M. V. O. Moutinho G. S. N. Eliel A. Righi R. N. Gontijo M. Paillet T. Michel Po-Wen Chiu P. Venezuela M. A. Pimenta
author_facet	M. V. O. Moutinho G. S. N. Eliel A. Righi R. N. Gontijo M. Paillet T. Michel Po-Wen Chiu P. Venezuela M. A. Pimenta
author_sort	M. V. O. Moutinho
title	Resonance Raman enhancement by the intralayer and interlayer electron–phonon processes in twisted bilayer graphene
title_short	Resonance Raman enhancement by the intralayer and interlayer electron–phonon processes in twisted bilayer graphene
title_full	Resonance Raman enhancement by the intralayer and interlayer electron–phonon processes in twisted bilayer graphene
title_fullStr	Resonance Raman enhancement by the intralayer and interlayer electron–phonon processes in twisted bilayer graphene
title_full_unstemmed	Resonance Raman enhancement by the intralayer and interlayer electron–phonon processes in twisted bilayer graphene
title_sort	resonance raman enhancement by the intralayer and interlayer electron–phonon processes in twisted bilayer graphene
publisher	Nature Portfolio
publishDate	2021
url	https://doaj.org/article/a43e16afd12945f5a733daefe6ccb552
work_keys_str_mv	AT mvomoutinho resonanceramanenhancementbytheintralayerandinterlayerelectronphononprocessesintwistedbilayergraphene AT gsneliel resonanceramanenhancementbytheintralayerandinterlayerelectronphononprocessesintwistedbilayergraphene AT arighi resonanceramanenhancementbytheintralayerandinterlayerelectronphononprocessesintwistedbilayergraphene AT rngontijo resonanceramanenhancementbytheintralayerandinterlayerelectronphononprocessesintwistedbilayergraphene AT mpaillet resonanceramanenhancementbytheintralayerandinterlayerelectronphononprocessesintwistedbilayergraphene AT tmichel resonanceramanenhancementbytheintralayerandinterlayerelectronphononprocessesintwistedbilayergraphene AT powenchiu resonanceramanenhancementbytheintralayerandinterlayerelectronphononprocessesintwistedbilayergraphene AT pvenezuela resonanceramanenhancementbytheintralayerandinterlayerelectronphononprocessesintwistedbilayergraphene AT mapimenta resonanceramanenhancementbytheintralayerandinterlayerelectronphononprocessesintwistedbilayergraphene
_version_	1718377344687669248

Resonance Raman enhancement by the intralayer and interlayer electron–phonon processes in twisted bilayer graphene

Ejemplares similares