Excitonic effects in energy loss spectra of freestanding graphene

Author(s)
Alberto Guandalini, Ryosuke Senga, Yung-Chang Lin, Kazu Suenaga, Andrea Ferretti, Daniele Varsano, Andrea Recchia, Paolo Barone, Francesco Mauri, Thomas Pichler, Christian Kramberger
Abstract

In this work we perform electron energy-loss spectroscopy (EELS) of freestanding graphene with high energy and momentum resolution to disentangle the quasielastic scattering from the excitation gap of Dirac electrons close to the optical limit. We show the importance of many-body effects on electronic excitations at finite transferred momentum by comparing measured EELS with ab initio calculations at increasing levels of theory. Quasi-particle corrections and excitonic effects are addressed within the GW approximation and Bethe-Salpeter equation, respectively. Both effects are essential in the description of the EEL spectra to obtain a quantitative agreement with experiments, with the position, dispersion, and shape of both the excitation gap and the π plasmon being significantly affected by excitonic effects.

Organisation(s)
Dynamics of Condensed Systems, Electronic Properties of Materials
External organisation(s)
Institute of Genetics and Biophysics "Adriano Buzzati-Traverso", CNR, Sapienza University of Rome, National Institute of Advanced Industrial Science and Technology (AIST), Italian Institute of Technology, Università degli Studi di Roma "Tor Vergata"
Journal
Nano Letters
Volume
23
Pages
11835–11841
No. of pages
7
ISSN
1530-6984
DOI
https://doi.org/10.48550/arXiv.2302.06367
Publication date
11-2023
Peer reviewed
Yes
Austrian Fields of Science 2012
103018 Materials physics
Keywords
Portal url
https://ucrisportal.univie.ac.at/en/publications/excitonic-effects-in-energy-loss-spectra-of-freestanding-graphene(2403a065-3d0b-416b-b46c-7096e0bfe48e).html