Raman bands of twisted bilayer graphene. (20th June 2017)

• Record Type: Journal Article
• Authors: Popov, Valentin N.
• Other Names: Paillet Matthieu guestEditor.; Parret Romain guestEditor.; Sauvajol Jean‐Louis guestEditor.; Colomban Philippe guestEditor.
• Is Part Of: Journal of Raman spectroscopy. Volume 49:Number 1(2018)
• Page Start: 31
• Page End: 35
• Publication Date: 2017-06-20
• Subjects: theory -- twisted bilayer graphene -- electronic structure -- dielectric function -- Raman excitation profile; Raman spectroscopy -- Periodicals; 535.846
• DOI: 10.1002/jrs.5189
• Languages: English
• ISSNs: 0377-0486

Abstract

Abstract : A theoretical approach to the modelling of the resonant Raman scattering by phonons in twisted bilayer graphene is developed and presented. The normally very large unit cells of twisted bilayer graphene hinder the large scale calculation of the electronic, vibrational, and optical properties by microscopic models. Here, a perturbative approach within a non‐orthogonal tight‐binding model is proposed that allows for a significant reduction of the computational time for such calculations. This approach is applied to the electronic band structure, electronic density of states, dielectric function, and Raman excitation profile of the most intense first‐order Raman band – the G band – for twisted bilayer graphene with up to a few hundred carbon atoms in the unit cell. The computational scheme can easily be extended to second‐order Raman bands of twisted bilayer graphene as well. The obtained theoretical predictions can be used for characterization of twisted bilayer graphene samples, using experimental Raman data. Copyright © 2017 John Wiley & Sons, Ltd. Abstract : We propose a perturbative approach within a non‐orthogonal tight‐binding model, which allows for a significant reduction of the computational time for calculation of the optical properties of twisted bilayer graphene. The dependence of the optical transition energies on the twist angle is derived from the dielectric function, and the behaviour of the Raman excitation profile of the G band is studied in detail. The obtained results can be used to support the structural characterization of twisted bilayer graphene.