TY  - CONF
AU  - Radović, Ivan
AU  - Despoja, Vito
AU  - Karbunar, Lazar
AU  - Mišković, Zoran
PY  - 2019
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/12707
AB  - We study the wake effect induced by an external charged particle which moves above various sy1-Al2O3-sy2 composites, where syi (i=1,2) may be vacuum, pristine (undoped) or doped graphene. The polarization functions of graphene sheets are obtained using two approaches within the random phase approximation [1]: an ab initio method and a method based on the massless Dirac fermion approximation. The dynamic response of the layer of Al2O3 (sapphire) is described by a dielectric function consisting of several Lorentzian terms [1]. We evaluate the total electrostatic potential in the plane of the upper graphene sheet (the wake potential). It is shown that in the low velocity limit (below a velocity threshold for the wake given by the Fermi speed of graphene) the charged particle excites only the transverse optical (TO) phonons in the Al2O3 slab and only those phonons contribute to the wake potential. It is also shown that the wake potential is only sensitive on the upper system sy2 such that if sy2 is vacuum then TO phonons give intensive oscillations which are strongly reduced if sy2 is graphene.
C3  - COST Action CA15107 meeting : Multicomp Multi-Functional Nano-Carbon Composite Materials Network : Aveiro Spring Meeting : Book of abstracts
T1  - Wake potential in a graphene-sapphire-graphene structure
SP  - 79
EP  - 79
UR  - https://hdl.handle.net/21.15107/rcub_vinar_12707
ER  - 

@conference{
author = "Radović, Ivan and Despoja, Vito and Karbunar, Lazar and Mišković, Zoran",
year = "2019",
abstract = "We study the wake effect induced by an external charged particle which moves above various sy1-Al2O3-sy2 composites, where syi (i=1,2) may be vacuum, pristine (undoped) or doped graphene. The polarization functions of graphene sheets are obtained using two approaches within the random phase approximation [1]: an ab initio method and a method based on the massless Dirac fermion approximation. The dynamic response of the layer of Al2O3 (sapphire) is described by a dielectric function consisting of several Lorentzian terms [1]. We evaluate the total electrostatic potential in the plane of the upper graphene sheet (the wake potential). It is shown that in the low velocity limit (below a velocity threshold for the wake given by the Fermi speed of graphene) the charged particle excites only the transverse optical (TO) phonons in the Al2O3 slab and only those phonons contribute to the wake potential. It is also shown that the wake potential is only sensitive on the upper system sy2 such that if sy2 is vacuum then TO phonons give intensive oscillations which are strongly reduced if sy2 is graphene.",
journal = "COST Action CA15107 meeting : Multicomp Multi-Functional Nano-Carbon Composite Materials Network : Aveiro Spring Meeting : Book of abstracts",
title = "Wake potential in a graphene-sapphire-graphene structure",
pages = "79-79",
url = "https://hdl.handle.net/21.15107/rcub_vinar_12707"
}

Radović, I., Despoja, V., Karbunar, L.,& Mišković, Z.. (2019). Wake potential in a graphene-sapphire-graphene structure. in COST Action CA15107 meeting : Multicomp Multi-Functional Nano-Carbon Composite Materials Network : Aveiro Spring Meeting : Book of abstracts, 79-79.
https://hdl.handle.net/21.15107/rcub_vinar_12707

Radović I, Despoja V, Karbunar L, Mišković Z. Wake potential in a graphene-sapphire-graphene structure. in COST Action CA15107 meeting : Multicomp Multi-Functional Nano-Carbon Composite Materials Network : Aveiro Spring Meeting : Book of abstracts. 2019;:79-79.
https://hdl.handle.net/21.15107/rcub_vinar_12707 .

Radović, Ivan, Despoja, Vito, Karbunar, Lazar, Mišković, Zoran, "Wake potential in a graphene-sapphire-graphene structure" in COST Action CA15107 meeting : Multicomp Multi-Functional Nano-Carbon Composite Materials Network : Aveiro Spring Meeting : Book of abstracts (2019):79-79,
https://hdl.handle.net/21.15107/rcub_vinar_12707 .

TY  - JOUR
AU  - Despoja, Vito
AU  - Radović, Ivan
AU  - Karbunar, Lazar
AU  - Kalinić, Ana
AU  - Mišković, Zoran L.
PY  - 2019
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/8595
AB  - We study the wake potential produced by an external charged particle that moves parallel to various sy1-Al2O3-sy2 sandwich-like composites, where the system syi (with i=1,2) may be vacuum, pristine graphene, or doped graphene. The effective dielectric function of the composites is obtained using three complementary methods for graphene's electronic response, based on the massless Dirac fermions (MDF) method, the extended hydrodynamic (eHD) model, and the ab initio approach. Three velocity regimes are explored with respect to the threshold for excitations of the Dirac plasmon in graphene, given by its Fermi velocity vF. In the low-velocity regime (below vF), only the transverse optical (TO) phonons in the Al2O3 layer contribute to the wake potential in the surface with sy2 (which is nearest to the charged particle), in a manner that is only sensitive to the composition of that system: if sy2 is vacuum, the TO phonons give rise to intense oscillations in the wake potential, which are strongly suppressed if sy2 is pristine or doped graphene. For intermediate velocities (above vF), the hybridized plasmon-TO phonon modes on both surfaces contribute to the wake potential in the surface with sy2, with the most dominant contribution coming from the hybridized Dirac-like plasmonic modes. In the high-velocity regime (well above vF), the highest-lying hybridized Dirac plasmon gives the dominant contribution to the wake potential, which exhibits a typical V-shaped wave-front pattern that lags behind the charged particle. It is found that the MDF method agrees very well with the results of the ab initio method for small and intermediate velocities. However, in the high-velocity regime, the high-energy π plasmon in graphene introduces new features in the wake potential in the form of fast oscillations, just behind the charged particle. Those oscillations in the wake potential are well described by both the eHD and the ab initio method, proving that the π plasmon indeed behaves as a collective mode.
T2  - Physical Review B
T1  - Wake potential in graphene-insulator-graphene composite systems
VL  - 100
IS  - 3
SP  - 035443
DO  - 10.1103/PhysRevB.100.035443
ER  - 

@article{
author = "Despoja, Vito and Radović, Ivan and Karbunar, Lazar and Kalinić, Ana and Mišković, Zoran L.",
year = "2019",
abstract = "We study the wake potential produced by an external charged particle that moves parallel to various sy1-Al2O3-sy2 sandwich-like composites, where the system syi (with i=1,2) may be vacuum, pristine graphene, or doped graphene. The effective dielectric function of the composites is obtained using three complementary methods for graphene's electronic response, based on the massless Dirac fermions (MDF) method, the extended hydrodynamic (eHD) model, and the ab initio approach. Three velocity regimes are explored with respect to the threshold for excitations of the Dirac plasmon in graphene, given by its Fermi velocity vF. In the low-velocity regime (below vF), only the transverse optical (TO) phonons in the Al2O3 layer contribute to the wake potential in the surface with sy2 (which is nearest to the charged particle), in a manner that is only sensitive to the composition of that system: if sy2 is vacuum, the TO phonons give rise to intense oscillations in the wake potential, which are strongly suppressed if sy2 is pristine or doped graphene. For intermediate velocities (above vF), the hybridized plasmon-TO phonon modes on both surfaces contribute to the wake potential in the surface with sy2, with the most dominant contribution coming from the hybridized Dirac-like plasmonic modes. In the high-velocity regime (well above vF), the highest-lying hybridized Dirac plasmon gives the dominant contribution to the wake potential, which exhibits a typical V-shaped wave-front pattern that lags behind the charged particle. It is found that the MDF method agrees very well with the results of the ab initio method for small and intermediate velocities. However, in the high-velocity regime, the high-energy π plasmon in graphene introduces new features in the wake potential in the form of fast oscillations, just behind the charged particle. Those oscillations in the wake potential are well described by both the eHD and the ab initio method, proving that the π plasmon indeed behaves as a collective mode.",
journal = "Physical Review B",
title = "Wake potential in graphene-insulator-graphene composite systems",
volume = "100",
number = "3",
pages = "035443",
doi = "10.1103/PhysRevB.100.035443"
}

Despoja, V., Radović, I., Karbunar, L., Kalinić, A.,& Mišković, Z. L.. (2019). Wake potential in graphene-insulator-graphene composite systems. in Physical Review B, 100(3), 035443.
https://doi.org/10.1103/PhysRevB.100.035443

Despoja V, Radović I, Karbunar L, Kalinić A, Mišković ZL. Wake potential in graphene-insulator-graphene composite systems. in Physical Review B. 2019;100(3):035443.
doi:10.1103/PhysRevB.100.035443 .

Despoja, Vito, Radović, Ivan, Karbunar, Lazar, Kalinić, Ana, Mišković, Zoran L., "Wake potential in graphene-insulator-graphene composite systems" in Physical Review B, 100, no. 3 (2019):035443,
https://doi.org/10.1103/PhysRevB.100.035443 . .

TY  - CONF
AU  - Despoja, Vito
AU  - Radović, Ivan
AU  - Karbunar, Lazar
AU  - Mišković, Zoran
PY  - 2018
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/12665
AB  - We study the wake effect due to excitation of a plasmon-phonon hybrid mode in a sandwich-like structure consisting of two doped graphene sheets, separated by a layer of Al2O3 (sapphire), which is induced by an external charged particle moving parallel to the structure.
PB  - University of Belgrade : Faculty of Physics
C3  - SPIG 2018 : 29th Summer School and International Symposium on the Physics of Ionized Gases : Contributed papers & abstracts of invited lectures, topical invited lectures, progress reports and workshop lectures
T1  - Wake effect due to excitation of plasmon-phonon hybrid modes in a graphene-sapphire-graphene structure by a moving charge
SP  - 82
EP  - 85
UR  - https://hdl.handle.net/21.15107/rcub_vinar_12665
ER  - 

@conference{
author = "Despoja, Vito and Radović, Ivan and Karbunar, Lazar and Mišković, Zoran",
year = "2018",
abstract = "We study the wake effect due to excitation of a plasmon-phonon hybrid mode in a sandwich-like structure consisting of two doped graphene sheets, separated by a layer of Al2O3 (sapphire), which is induced by an external charged particle moving parallel to the structure.",
publisher = "University of Belgrade : Faculty of Physics",
journal = "SPIG 2018 : 29th Summer School and International Symposium on the Physics of Ionized Gases : Contributed papers & abstracts of invited lectures, topical invited lectures, progress reports and workshop lectures",
title = "Wake effect due to excitation of plasmon-phonon hybrid modes in a graphene-sapphire-graphene structure by a moving charge",
pages = "82-85",
url = "https://hdl.handle.net/21.15107/rcub_vinar_12665"
}

Despoja, V., Radović, I., Karbunar, L.,& Mišković, Z.. (2018). Wake effect due to excitation of plasmon-phonon hybrid modes in a graphene-sapphire-graphene structure by a moving charge. in SPIG 2018 : 29th Summer School and International Symposium on the Physics of Ionized Gases : Contributed papers & abstracts of invited lectures, topical invited lectures, progress reports and workshop lectures
University of Belgrade : Faculty of Physics., 82-85.
https://hdl.handle.net/21.15107/rcub_vinar_12665

Despoja V, Radović I, Karbunar L, Mišković Z. Wake effect due to excitation of plasmon-phonon hybrid modes in a graphene-sapphire-graphene structure by a moving charge. in SPIG 2018 : 29th Summer School and International Symposium on the Physics of Ionized Gases : Contributed papers & abstracts of invited lectures, topical invited lectures, progress reports and workshop lectures. 2018;:82-85.
https://hdl.handle.net/21.15107/rcub_vinar_12665 .

Despoja, Vito, Radović, Ivan, Karbunar, Lazar, Mišković, Zoran, "Wake effect due to excitation of plasmon-phonon hybrid modes in a graphene-sapphire-graphene structure by a moving charge" in SPIG 2018 : 29th Summer School and International Symposium on the Physics of Ionized Gases : Contributed papers & abstracts of invited lectures, topical invited lectures, progress reports and workshop lectures (2018):82-85,
https://hdl.handle.net/21.15107/rcub_vinar_12665 .

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 . .

TY  - CONF
AU  - Karbunar, Lazar
AU  - Borka, Duško
AU  - Radović, Ivan
PY  - 2016
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/7117
AB  - In this paper we investigate possibility of carbon nanotubes characterization by differentiation in spatial and angular distribution fingerprints obtained by fast ions channeling. We analyze straight single walled carbon nanotubes (SWNTs) interacting with fast ion beams. We calculate the image potential for protons moving through the four types of SWNTs at the speeds of 3 a.u.. We calculate total potential in straight carbon nanotubes. Interaction of channelled ions with nanotube electrons we calculate by linearized, two dimensional (2D), extended two-fluid hydrodynamic model. We simulate ion beams channelling through the four types of SWNTs under calculated conditions of interaction and calculate spatial and angular distributions of channelled particles what we use as method for different SWNTs characterization.
C3  - 5th Mediterranean Conference on Embedded Computing : Proceedings
T1  - Carbon Nanotubes Characterization by Channeled Fast Ions Spatial and Angular Distribution Fingerprints
SP  - 68
EP  - 71
DO  - 10.1109/meco.2016.7525705
UR  - https://hdl.handle.net/21.15107/rcub_vinar_7117
ER  - 

@conference{
author = "Karbunar, Lazar and Borka, Duško and Radović, Ivan",
year = "2016",
abstract = "In this paper we investigate possibility of carbon nanotubes characterization by differentiation in spatial and angular distribution fingerprints obtained by fast ions channeling. We analyze straight single walled carbon nanotubes (SWNTs) interacting with fast ion beams. We calculate the image potential for protons moving through the four types of SWNTs at the speeds of 3 a.u.. We calculate total potential in straight carbon nanotubes. Interaction of channelled ions with nanotube electrons we calculate by linearized, two dimensional (2D), extended two-fluid hydrodynamic model. We simulate ion beams channelling through the four types of SWNTs under calculated conditions of interaction and calculate spatial and angular distributions of channelled particles what we use as method for different SWNTs characterization.",
journal = "5th Mediterranean Conference on Embedded Computing : Proceedings",
title = "Carbon Nanotubes Characterization by Channeled Fast Ions Spatial and Angular Distribution Fingerprints",
pages = "68-71",
doi = "10.1109/meco.2016.7525705",
url = "https://hdl.handle.net/21.15107/rcub_vinar_7117"
}

Karbunar, L., Borka, D.,& Radović, I.. (2016). Carbon Nanotubes Characterization by Channeled Fast Ions Spatial and Angular Distribution Fingerprints. in 5th Mediterranean Conference on Embedded Computing : Proceedings, 68-71.
https://doi.org/10.1109/meco.2016.7525705
https://hdl.handle.net/21.15107/rcub_vinar_7117

Karbunar L, Borka D, Radović I. Carbon Nanotubes Characterization by Channeled Fast Ions Spatial and Angular Distribution Fingerprints. in 5th Mediterranean Conference on Embedded Computing : Proceedings. 2016;:68-71.
doi:10.1109/meco.2016.7525705
https://hdl.handle.net/21.15107/rcub_vinar_7117 .

Karbunar, Lazar, Borka, Duško, Radović, Ivan, "Carbon Nanotubes Characterization by Channeled Fast Ions Spatial and Angular Distribution Fingerprints" in 5th Mediterranean Conference on Embedded Computing : Proceedings (2016):68-71,
https://doi.org/10.1109/meco.2016.7525705 .,
https://hdl.handle.net/21.15107/rcub_vinar_7117 .

TY  - CONF
AU  - Karbunar, Lazar
AU  - Despoja, Vito
AU  - Radović, Ivan
AU  - Mišković, Zoran
PY  - 2016
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/12644
AB  - We present a method to introduce several graphene sheets into the non-retarded Green’s function for a layered structure containing polar insulators, which support transverse optical phonon modes. Dispersion relations are derived to illustrate hybridization of Dirac plasmons in two graphene sheets with phonon modes in an oxide spacer layer between them.
PB  - University of Belgrade : Faculty of Physics
C3  - SPIG 2016 : 28th Summer School and International Symposium on the Physics of Ionized Gases : Contributed papers & abstracts of invited lectures, topical invited lectures, progress reports and workshop lectures
T1  - Plasmon-phonon hybridization in layered structures including graphene
SP  - 154
EP  - 157
UR  - https://hdl.handle.net/21.15107/rcub_vinar_12644
ER  - 

@conference{
author = "Karbunar, Lazar and Despoja, Vito and Radović, Ivan and Mišković, Zoran",
year = "2016",
abstract = "We present a method to introduce several graphene sheets into the non-retarded Green’s function for a layered structure containing polar insulators, which support transverse optical phonon modes. Dispersion relations are derived to illustrate hybridization of Dirac plasmons in two graphene sheets with phonon modes in an oxide spacer layer between them.",
publisher = "University of Belgrade : Faculty of Physics",
journal = "SPIG 2016 : 28th Summer School and International Symposium on the Physics of Ionized Gases : Contributed papers & abstracts of invited lectures, topical invited lectures, progress reports and workshop lectures",
title = "Plasmon-phonon hybridization in layered structures including graphene",
pages = "154-157",
url = "https://hdl.handle.net/21.15107/rcub_vinar_12644"
}

Karbunar, L., Despoja, V., Radović, I.,& Mišković, Z.. (2016). Plasmon-phonon hybridization in layered structures including graphene. in SPIG 2016 : 28th Summer School and International Symposium on the Physics of Ionized Gases : Contributed papers & abstracts of invited lectures, topical invited lectures, progress reports and workshop lectures
University of Belgrade : Faculty of Physics., 154-157.
https://hdl.handle.net/21.15107/rcub_vinar_12644

Karbunar L, Despoja V, Radović I, Mišković Z. Plasmon-phonon hybridization in layered structures including graphene. in SPIG 2016 : 28th Summer School and International Symposium on the Physics of Ionized Gases : Contributed papers & abstracts of invited lectures, topical invited lectures, progress reports and workshop lectures. 2016;:154-157.
https://hdl.handle.net/21.15107/rcub_vinar_12644 .

Karbunar, Lazar, Despoja, Vito, Radović, Ivan, Mišković, Zoran, "Plasmon-phonon hybridization in layered structures including graphene" in SPIG 2016 : 28th Summer School and International Symposium on the Physics of Ionized Gases : Contributed papers & abstracts of invited lectures, topical invited lectures, progress reports and workshop lectures (2016):154-157,
https://hdl.handle.net/21.15107/rcub_vinar_12644 .