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/2403a065-3d0b-416b-b46c-7096e0bfe48e