TY  - JOUR
AU  - Đorđević, Tijana
AU  - Radović, Ivan
AU  - Despoja, Vito
AU  - Lyon, Keenan
AU  - Borka, Duško
AU  - Mišković, Zoran L.
PY  - 2018
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/1831
AB  - We present an analytical modeling of the electron energy loss (EEL) spectroscopy data for free-standing graphene obtained by scanning transmission electron microscope. The probability density for energy loss of fast electrons traversing graphene under normal incidence is evaluated using an optical approximation based on the conductivity of graphene given in the local, i.e., frequency-dependent form derived by both a two-dimensional, two-fluid extended hydrodynamic (eHD) model and an ab initio method. We compare the results for the real and imaginary parts of the optical conductivity in graphene obtained by these two methods. The calculated probability density is directly compared with the EEL spectra from three independent experiments and we find very good agreement, especially in the case of the eHD model. Furthermore, we point out that the subtraction of the zero-loss peak from the experimental EEL spectra has a strong influence on the analytical model for the EEL spectroscopy data. (C) 2017 Elsevier B.V. All rights reserved.
T2  - Ultramicroscopy
T1  - Analytical modeling of electron energy loss spectroscopy of graphene: Ab initio study versus extended hydrodynamic model
VL  - 184
SP  - 134
EP  - 142
DO  - 10.1016/j.ultramic.2017.08.014
ER  - 

@article{
author = "Đorđević, Tijana and Radović, Ivan and Despoja, Vito and Lyon, Keenan and Borka, Duško and Mišković, Zoran L.",
year = "2018",
abstract = "We present an analytical modeling of the electron energy loss (EEL) spectroscopy data for free-standing graphene obtained by scanning transmission electron microscope. The probability density for energy loss of fast electrons traversing graphene under normal incidence is evaluated using an optical approximation based on the conductivity of graphene given in the local, i.e., frequency-dependent form derived by both a two-dimensional, two-fluid extended hydrodynamic (eHD) model and an ab initio method. We compare the results for the real and imaginary parts of the optical conductivity in graphene obtained by these two methods. The calculated probability density is directly compared with the EEL spectra from three independent experiments and we find very good agreement, especially in the case of the eHD model. Furthermore, we point out that the subtraction of the zero-loss peak from the experimental EEL spectra has a strong influence on the analytical model for the EEL spectroscopy data. (C) 2017 Elsevier B.V. All rights reserved.",
journal = "Ultramicroscopy",
title = "Analytical modeling of electron energy loss spectroscopy of graphene: Ab initio study versus extended hydrodynamic model",
volume = "184",
pages = "134-142",
doi = "10.1016/j.ultramic.2017.08.014"
}

Đorđević, T., Radović, I., Despoja, V., Lyon, K., Borka, D.,& Mišković, Z. L.. (2018). Analytical modeling of electron energy loss spectroscopy of graphene: Ab initio study versus extended hydrodynamic model. in Ultramicroscopy, 184, 134-142.
https://doi.org/10.1016/j.ultramic.2017.08.014

Đorđević T, Radović I, Despoja V, Lyon K, Borka D, Mišković ZL. Analytical modeling of electron energy loss spectroscopy of graphene: Ab initio study versus extended hydrodynamic model. in Ultramicroscopy. 2018;184:134-142.
doi:10.1016/j.ultramic.2017.08.014 .

Đorđević, Tijana, Radović, Ivan, Despoja, Vito, Lyon, Keenan, Borka, Duško, Mišković, Zoran L., "Analytical modeling of electron energy loss spectroscopy of graphene: Ab initio study versus extended hydrodynamic model" in Ultramicroscopy, 184 (2018):134-142,
https://doi.org/10.1016/j.ultramic.2017.08.014 . .

TY  - CONF
AU  - Đorđević, Tijana
AU  - Radović, Ivan
AU  - Borka, Duško
AU  - Mišković, Zoran L.
PY  - 2017
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/12674
AB  - We study the effects of variation in the doping density of graphene on hybridization taking place
between its Dirac plasmon and the surface optical phonon modes in a SiO2 substrate, and show that
this hybridization may be probed by a point charge that moves over graphene at a speed comparable
to graphene’s Fermi speed. Using the dielectric-response formalism within the random phase
approximation, we show that the plasmon-phonon hybridization exerts strong effects on the wake
pattern in the induced potential in the plane of graphene, as well as on the stopping and image forces
on the incident charge, in a manner that may be controlled by changing the doping density of
graphene.
PB  - Tallinn, Estonia : Tallinn University of Technology
C3  - 17th Baltic Polymer Symposium : Book of Abstracts
T1  - Probing the plasmon-phonon hybridization in supported graphene by externally moving charged particles
SP  - 72
EP  - 72
UR  - https://hdl.handle.net/21.15107/rcub_vinar_12674
ER  - 

@conference{
author = "Đorđević, Tijana and Radović, Ivan and Borka, Duško and Mišković, Zoran L.",
year = "2017",
abstract = "We study the effects of variation in the doping density of graphene on hybridization taking place
between its Dirac plasmon and the surface optical phonon modes in a SiO2 substrate, and show that
this hybridization may be probed by a point charge that moves over graphene at a speed comparable
to graphene’s Fermi speed. Using the dielectric-response formalism within the random phase
approximation, we show that the plasmon-phonon hybridization exerts strong effects on the wake
pattern in the induced potential in the plane of graphene, as well as on the stopping and image forces
on the incident charge, in a manner that may be controlled by changing the doping density of
graphene.",
publisher = "Tallinn, Estonia : Tallinn University of Technology",
journal = "17th Baltic Polymer Symposium : Book of Abstracts",
title = "Probing the plasmon-phonon hybridization in supported graphene by externally moving charged particles",
pages = "72-72",
url = "https://hdl.handle.net/21.15107/rcub_vinar_12674"
}

Đorđević, T., Radović, I., Borka, D.,& Mišković, Z. L.. (2017). Probing the plasmon-phonon hybridization in supported graphene by externally moving charged particles. in 17th Baltic Polymer Symposium : Book of Abstracts
Tallinn, Estonia : Tallinn University of Technology., 72-72.
https://hdl.handle.net/21.15107/rcub_vinar_12674

Đorđević T, Radović I, Borka D, Mišković ZL. Probing the plasmon-phonon hybridization in supported graphene by externally moving charged particles. in 17th Baltic Polymer Symposium : Book of Abstracts. 2017;:72-72.
https://hdl.handle.net/21.15107/rcub_vinar_12674 .

Đorđević, Tijana, Radović, Ivan, Borka, Duško, Mišković, Zoran L., "Probing the plasmon-phonon hybridization in supported graphene by externally moving charged particles" in 17th Baltic Polymer Symposium : Book of Abstracts (2017):72-72,
https://hdl.handle.net/21.15107/rcub_vinar_12674 .

TY  - JOUR
AU  - Despoja, Vito
AU  - Đorđević, Tijana
AU  - Karbunar, Lazar
AU  - Radović, Ivan
AU  - Mišković, Zoran L.
PY  - 2017
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/1693
AB  - The propagator of a dynamically screened Coulomb interaction W in a sandwichlike structure consisting of two graphene layers separated by a slab of Al2O3 (or vacuum) is derived from single-layer graphene response functions and by using a local dielectric function for the bulk Al2O3. The response function of graphene is obtained using two approaches within the random phase approximation (RPA): an ab initio method that includes all electronic bands in graphene and a computationally less demanding method based on the massless Dirac fermion (MDF) approximation for the low-energy excitations of electrons in the p bands. The propagator W is used to derive an expression for the effective dielectric function of our sandwich structure, which is relevant for the reflection electron energy loss spectroscopy of its surface. Focusing on the range of frequencies from THz to mid-infrared, special attention is paid to finding an accurate optical limit in the ab initio method, where the response function is expressed in terms of a frequency-dependent conductivity of graphene. It was shown that the optical limit suffices for describing hybridization between the Dirac plasmons in graphene layers and the Fuchs-Kliewer phonons in both surfaces of the Al2O3 slab, and that the spectra obtained from both the ab initio method and the MDF approximation in the optical limit agree perfectly well for wave numbers up to about 0.1 nm(-1). Going beyond the optical limit, the agreement between the full ab initio method and the MDF approximation was found to extend to wave numbers up to about 0.3 nm(-1) for doped graphene layers with the Fermi energy of 0.2 eV.
T2  - Physical Review B: Condensed Matter and Materials Physics
T1  - Ab initio study of the electron energy loss function in a graphene-sapphire-graphene composite system
VL  - 96
IS  - 7
DO  - 10.1103/PhysRevB.96.075433
ER  - 

@article{
author = "Despoja, Vito and Đorđević, Tijana and Karbunar, Lazar and Radović, Ivan and Mišković, Zoran L.",
year = "2017",
abstract = "The propagator of a dynamically screened Coulomb interaction W in a sandwichlike structure consisting of two graphene layers separated by a slab of Al2O3 (or vacuum) is derived from single-layer graphene response functions and by using a local dielectric function for the bulk Al2O3. The response function of graphene is obtained using two approaches within the random phase approximation (RPA): an ab initio method that includes all electronic bands in graphene and a computationally less demanding method based on the massless Dirac fermion (MDF) approximation for the low-energy excitations of electrons in the p bands. The propagator W is used to derive an expression for the effective dielectric function of our sandwich structure, which is relevant for the reflection electron energy loss spectroscopy of its surface. Focusing on the range of frequencies from THz to mid-infrared, special attention is paid to finding an accurate optical limit in the ab initio method, where the response function is expressed in terms of a frequency-dependent conductivity of graphene. It was shown that the optical limit suffices for describing hybridization between the Dirac plasmons in graphene layers and the Fuchs-Kliewer phonons in both surfaces of the Al2O3 slab, and that the spectra obtained from both the ab initio method and the MDF approximation in the optical limit agree perfectly well for wave numbers up to about 0.1 nm(-1). Going beyond the optical limit, the agreement between the full ab initio method and the MDF approximation was found to extend to wave numbers up to about 0.3 nm(-1) for doped graphene layers with the Fermi energy of 0.2 eV.",
journal = "Physical Review B: Condensed Matter and Materials Physics",
title = "Ab initio study of the electron energy loss function in a graphene-sapphire-graphene composite system",
volume = "96",
number = "7",
doi = "10.1103/PhysRevB.96.075433"
}

Despoja, V., Đorđević, T., Karbunar, L., Radović, I.,& Mišković, Z. L.. (2017). Ab initio study of the electron energy loss function in a graphene-sapphire-graphene composite system. in Physical Review B: Condensed Matter and Materials Physics, 96(7).
https://doi.org/10.1103/PhysRevB.96.075433

Despoja V, Đorđević T, Karbunar L, Radović I, Mišković ZL. Ab initio study of the electron energy loss function in a graphene-sapphire-graphene composite system. in Physical Review B: Condensed Matter and Materials Physics. 2017;96(7).
doi:10.1103/PhysRevB.96.075433 .

Despoja, Vito, Đorđević, Tijana, Karbunar, Lazar, Radović, Ivan, Mišković, Zoran L., "Ab initio study of the electron energy loss function in a graphene-sapphire-graphene composite system" in Physical Review B: Condensed Matter and Materials Physics, 96, no. 7 (2017),
https://doi.org/10.1103/PhysRevB.96.075433 . .