TY  - JOUR
AU  - Mišković, Zoran L.
AU  - Moshayedi, Milad
AU  - Preciado-Rivas, Maria Rosa
AU  - Jakovac, Josip
AU  - Radović, Ivan
AU  - Despoja, Vito
PY  - 2023
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/11030
AB  - We use Kramers-Kronig analysis and ab initio calculations to develop a simple analytical method for including the effects of high-energy interband electron transitions in the density polarization function of doped graphene and doped phosphorene in the optical limit. The resulting formulas are suitable for applications in the terahertz to the mid-infrared range of frequencies, where the interband electron transitions are shown to give rise to static screening with a suitably chosen in-plane polarizability. In the case of phosphorene, each component of its static polarizability tensor can be computed from a sum-rule–like formula using the ab initio data for the real part of the corresponding component of the full optical interband conductivity tensor of that material.
T2  - Radiation Effects and Defects in Solids
T1  - Modeling of the interband transitions in the optical conductivity of doped two-dimensional materials in the terahertz to the infrared frequency range: the case studies of graphene and phosphorene
VL  - 178
IS  - 1-2
SP  - 54
EP  - 71
DO  - 10.1080/10420150.2023.2186870
ER  - 

@article{
author = "Mišković, Zoran L. and Moshayedi, Milad and Preciado-Rivas, Maria Rosa and Jakovac, Josip and Radović, Ivan and Despoja, Vito",
year = "2023",
abstract = "We use Kramers-Kronig analysis and ab initio calculations to develop a simple analytical method for including the effects of high-energy interband electron transitions in the density polarization function of doped graphene and doped phosphorene in the optical limit. The resulting formulas are suitable for applications in the terahertz to the mid-infrared range of frequencies, where the interband electron transitions are shown to give rise to static screening with a suitably chosen in-plane polarizability. In the case of phosphorene, each component of its static polarizability tensor can be computed from a sum-rule–like formula using the ab initio data for the real part of the corresponding component of the full optical interband conductivity tensor of that material.",
journal = "Radiation Effects and Defects in Solids",
title = "Modeling of the interband transitions in the optical conductivity of doped two-dimensional materials in the terahertz to the infrared frequency range: the case studies of graphene and phosphorene",
volume = "178",
number = "1-2",
pages = "54-71",
doi = "10.1080/10420150.2023.2186870"
}

Mišković, Z. L., Moshayedi, M., Preciado-Rivas, M. R., Jakovac, J., Radović, I.,& Despoja, V.. (2023). Modeling of the interband transitions in the optical conductivity of doped two-dimensional materials in the terahertz to the infrared frequency range: the case studies of graphene and phosphorene. in Radiation Effects and Defects in Solids, 178(1-2), 54-71.
https://doi.org/10.1080/10420150.2023.2186870

Mišković ZL, Moshayedi M, Preciado-Rivas MR, Jakovac J, Radović I, Despoja V. Modeling of the interband transitions in the optical conductivity of doped two-dimensional materials in the terahertz to the infrared frequency range: the case studies of graphene and phosphorene. in Radiation Effects and Defects in Solids. 2023;178(1-2):54-71.
doi:10.1080/10420150.2023.2186870 .

Mišković, Zoran L., Moshayedi, Milad, Preciado-Rivas, Maria Rosa, Jakovac, Josip, Radović, Ivan, Despoja, Vito, "Modeling of the interband transitions in the optical conductivity of doped two-dimensional materials in the terahertz to the infrared frequency range: the case studies of graphene and phosphorene" in Radiation Effects and Defects in Solids, 178, no. 1-2 (2023):54-71,
https://doi.org/10.1080/10420150.2023.2186870 . .

TY  - CONF
AU  - Kalinić, Ana
AU  - Radović, Ivan
AU  - Despoja, Vito
AU  - Karbunar, Lazar
AU  - Mišković, Zoran
PY  - 2023
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/12056
AB  - We investigate the stopping and image forces acting on an external charged particle moving parallel to a sandwich-like structure consisting of two graphene sheets separated by a layer of Al2O3 (sapphire), as depicted in FIG. 1. The effective dielectric function of the system is obtained using two descriptions of the electronic response of doped graphene: an ab initio method based on the time-dependent density functional theory calculations and an analytical expression based on the massless Dirac fermion (MDF) approximation for graphene π bands. It is found that the main discrepancies between the two methods come from the high-energy interband electron transitions, which are included in the ab initio method but not in the MDF method. Special attention is paid to the regime of low-particle speeds, where the MDF method compares well with the ab initio method, but the modeling is sensitive to the effects of finite temperature and the treatment of phenomenological damping. We also provide a semi-analytical analysis based on a modal decomposition of the energy loss function, for which we discuss the limit of a thick graphene-Al2O3-graphene structure.
C3  - SFKM 2023 : The 21st Symposium on Condensed Matter Physics : Book of abstracts
T1  - Dynamic-Polarization Forces Acting On A Charged Particle Moving Over A Graphene-Sapphire-Graphene Heterostructure
SP  - 82
EP  - 82
UR  - https://hdl.handle.net/21.15107/rcub_vinar_12056
ER  - 

@conference{
author = "Kalinić, Ana and Radović, Ivan and Despoja, Vito and Karbunar, Lazar and Mišković, Zoran",
year = "2023",
abstract = "We investigate the stopping and image forces acting on an external charged particle moving parallel to a sandwich-like structure consisting of two graphene sheets separated by a layer of Al2O3 (sapphire), as depicted in FIG. 1. The effective dielectric function of the system is obtained using two descriptions of the electronic response of doped graphene: an ab initio method based on the time-dependent density functional theory calculations and an analytical expression based on the massless Dirac fermion (MDF) approximation for graphene π bands. It is found that the main discrepancies between the two methods come from the high-energy interband electron transitions, which are included in the ab initio method but not in the MDF method. Special attention is paid to the regime of low-particle speeds, where the MDF method compares well with the ab initio method, but the modeling is sensitive to the effects of finite temperature and the treatment of phenomenological damping. We also provide a semi-analytical analysis based on a modal decomposition of the energy loss function, for which we discuss the limit of a thick graphene-Al2O3-graphene structure.",
journal = "SFKM 2023 : The 21st Symposium on Condensed Matter Physics : Book of abstracts",
title = "Dynamic-Polarization Forces Acting On A Charged Particle Moving Over A Graphene-Sapphire-Graphene Heterostructure",
pages = "82-82",
url = "https://hdl.handle.net/21.15107/rcub_vinar_12056"
}

Kalinić, A., Radović, I., Despoja, V., Karbunar, L.,& Mišković, Z.. (2023). Dynamic-Polarization Forces Acting On A Charged Particle Moving Over A Graphene-Sapphire-Graphene Heterostructure. in SFKM 2023 : The 21st Symposium on Condensed Matter Physics : Book of abstracts, 82-82.
https://hdl.handle.net/21.15107/rcub_vinar_12056

Kalinić A, Radović I, Despoja V, Karbunar L, Mišković Z. Dynamic-Polarization Forces Acting On A Charged Particle Moving Over A Graphene-Sapphire-Graphene Heterostructure. in SFKM 2023 : The 21st Symposium on Condensed Matter Physics : Book of abstracts. 2023;:82-82.
https://hdl.handle.net/21.15107/rcub_vinar_12056 .

Kalinić, Ana, Radović, Ivan, Despoja, Vito, Karbunar, Lazar, Mišković, Zoran, "Dynamic-Polarization Forces Acting On A Charged Particle Moving Over A Graphene-Sapphire-Graphene Heterostructure" in SFKM 2023 : The 21st Symposium on Condensed Matter Physics : Book of abstracts (2023):82-82,
https://hdl.handle.net/21.15107/rcub_vinar_12056 .

TY  - CONF
AU  - Kalinić, Ana
AU  - Radović, Ivan
AU  - Despoja, Vito
AU  - Karbunar, Lazar
AU  - Mišković, Zoran
PY  - 2023
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/12074
AB  - In our previous publication [1] we studied the wake potential induced by an external charged particle that moves parallel to various sy1 -Al2O3-sy2 composites, where syi (with i=1,2) may be vacuum, pristine (undoped) graphene, or doped graphene. Several important parameters were fixed at their respective typical values: the distance of the charged particle from the closest surface, the thickness of the Al2O3 layer, and the doping density of graphene. In our recent publication [2] we presented a detailed study of the effects due to variations of all those parameters in the case of the wake potential produced by the charged particle moving parallel to the graphene-Al2O3-graphene composite system. In both mentioned publications we assumed a zero gap between graphene and insulator to simplify calculations. In this work we assign for the first time a finite gap size between graphene and insulator, and vary the speed of the projectile moving parallel to the structure and the particle distance. Using the Dyson-Schwinger equation [3] we recalculate the wake potential in the graphene-insulator-graphene heterostructure and study the effects of the graphene-insulator distance. The polarization functions of graphene sheets are obtained using two approaches within the random phase approximation [3]: an ab initio method and a method based on the massless Dirac fermion approximation. The dynamic response of the insulator layer is described by a dielectric function consisting of several Lorentzian terms.
C3  - COST 18234 Meeting in Israel : International Conference on Development of Nanocrystal Materials Through Computational Modelling : Posters abstracts
T1  - Wake Potential in Graphene-insulator-graphene Heterostructure: the Role of Graphene-insulator Distance
SP  - 5
EP  - 5
UR  - https://hdl.handle.net/21.15107/rcub_vinar_12074
ER  - 

@conference{
author = "Kalinić, Ana and Radović, Ivan and Despoja, Vito and Karbunar, Lazar and Mišković, Zoran",
year = "2023",
abstract = "In our previous publication [1] we studied the wake potential induced by an external charged particle that moves parallel to various sy1 -Al2O3-sy2 composites, where syi (with i=1,2) may be vacuum, pristine (undoped) graphene, or doped graphene. Several important parameters were fixed at their respective typical values: the distance of the charged particle from the closest surface, the thickness of the Al2O3 layer, and the doping density of graphene. In our recent publication [2] we presented a detailed study of the effects due to variations of all those parameters in the case of the wake potential produced by the charged particle moving parallel to the graphene-Al2O3-graphene composite system. In both mentioned publications we assumed a zero gap between graphene and insulator to simplify calculations. In this work we assign for the first time a finite gap size between graphene and insulator, and vary the speed of the projectile moving parallel to the structure and the particle distance. Using the Dyson-Schwinger equation [3] we recalculate the wake potential in the graphene-insulator-graphene heterostructure and study the effects of the graphene-insulator distance. The polarization functions of graphene sheets are obtained using two approaches within the random phase approximation [3]: an ab initio method and a method based on the massless Dirac fermion approximation. The dynamic response of the insulator layer is described by a dielectric function consisting of several Lorentzian terms.",
journal = "COST 18234 Meeting in Israel : International Conference on Development of Nanocrystal Materials Through Computational Modelling : Posters abstracts",
title = "Wake Potential in Graphene-insulator-graphene Heterostructure: the Role of Graphene-insulator Distance",
pages = "5-5",
url = "https://hdl.handle.net/21.15107/rcub_vinar_12074"
}

Kalinić, A., Radović, I., Despoja, V., Karbunar, L.,& Mišković, Z.. (2023). Wake Potential in Graphene-insulator-graphene Heterostructure: the Role of Graphene-insulator Distance. in COST 18234 Meeting in Israel : International Conference on Development of Nanocrystal Materials Through Computational Modelling : Posters abstracts, 5-5.
https://hdl.handle.net/21.15107/rcub_vinar_12074

Kalinić A, Radović I, Despoja V, Karbunar L, Mišković Z. Wake Potential in Graphene-insulator-graphene Heterostructure: the Role of Graphene-insulator Distance. in COST 18234 Meeting in Israel : International Conference on Development of Nanocrystal Materials Through Computational Modelling : Posters abstracts. 2023;:5-5.
https://hdl.handle.net/21.15107/rcub_vinar_12074 .

Kalinić, Ana, Radović, Ivan, Despoja, Vito, Karbunar, Lazar, Mišković, Zoran, "Wake Potential in Graphene-insulator-graphene Heterostructure: the Role of Graphene-insulator Distance" in COST 18234 Meeting in Israel : International Conference on Development of Nanocrystal Materials Through Computational Modelling : Posters abstracts (2023):5-5,
https://hdl.handle.net/21.15107/rcub_vinar_12074 .

TY  - JOUR
AU  - Marušić, Leonardo
AU  - Kalinić, Ana
AU  - Radović, Ivan
AU  - Jakovac, Josip
AU  - Mišković, Zoran L.
AU  - Despoja, Vito
PY  - 2022
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/10245
AB  - Graphene doped by alkali atoms (ACx) supports two heavily populated bands (π and σ) crossing the Fermi level, which enables the formation of two intense two-dimensional plasmons: the Dirac plasmon (DP) and the acoustic plasmon (AP). Although the mechanism of the formation of these plasmons in electrostatically biased graphene or at noble metal surfaces is well known, the mechanism of their formation in alkali-doped graphenes is still not completely understood. We shall demonstrate that two isoelectronic systems, KC8 and CsC8, support substantially different plasmonic spectra: the KC8 supports a sharp DP and a well-defined AP, while the CsC8 supports a broad DP and does not support an AP at all. We shall demonstrate that the AP in an ACx is not, as previously believed, just a consequence of the interplay of the π and σ intraband transitions, but a very subtle interplay between these transitions and the background screening, caused by the out-of-plane interband C(π)→A(σ) transitions.
T2  - International Journal of Molecular Sciences
T1  - Resolving the Mechanism of Acoustic Plasmon Instability in Graphene Doped by Alkali Metals
VL  - 23
IS  - 9
SP  - 4770
DO  - 10.3390/ijms23094770
ER  - 

@article{
author = "Marušić, Leonardo and Kalinić, Ana and Radović, Ivan and Jakovac, Josip and Mišković, Zoran L. and Despoja, Vito",
year = "2022",
abstract = "Graphene doped by alkali atoms (ACx) supports two heavily populated bands (π and σ) crossing the Fermi level, which enables the formation of two intense two-dimensional plasmons: the Dirac plasmon (DP) and the acoustic plasmon (AP). Although the mechanism of the formation of these plasmons in electrostatically biased graphene or at noble metal surfaces is well known, the mechanism of their formation in alkali-doped graphenes is still not completely understood. We shall demonstrate that two isoelectronic systems, KC8 and CsC8, support substantially different plasmonic spectra: the KC8 supports a sharp DP and a well-defined AP, while the CsC8 supports a broad DP and does not support an AP at all. We shall demonstrate that the AP in an ACx is not, as previously believed, just a consequence of the interplay of the π and σ intraband transitions, but a very subtle interplay between these transitions and the background screening, caused by the out-of-plane interband C(π)→A(σ) transitions.",
journal = "International Journal of Molecular Sciences",
title = "Resolving the Mechanism of Acoustic Plasmon Instability in Graphene Doped by Alkali Metals",
volume = "23",
number = "9",
pages = "4770",
doi = "10.3390/ijms23094770"
}

Marušić, L., Kalinić, A., Radović, I., Jakovac, J., Mišković, Z. L.,& Despoja, V.. (2022). Resolving the Mechanism of Acoustic Plasmon Instability in Graphene Doped by Alkali Metals. in International Journal of Molecular Sciences, 23(9), 4770.
https://doi.org/10.3390/ijms23094770

Marušić L, Kalinić A, Radović I, Jakovac J, Mišković ZL, Despoja V. Resolving the Mechanism of Acoustic Plasmon Instability in Graphene Doped by Alkali Metals. in International Journal of Molecular Sciences. 2022;23(9):4770.
doi:10.3390/ijms23094770 .

Marušić, Leonardo, Kalinić, Ana, Radović, Ivan, Jakovac, Josip, Mišković, Zoran L., Despoja, Vito, "Resolving the Mechanism of Acoustic Plasmon Instability in Graphene Doped by Alkali Metals" in International Journal of Molecular Sciences, 23, no. 9 (2022):4770,
https://doi.org/10.3390/ijms23094770 . .

TY  - JOUR
AU  - Kalinić, Ana
AU  - Despoja, Vito
AU  - Radović, Ivan
AU  - Karbunar, Lazar
AU  - Mišković, Zoran L.
PY  - 2022
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/10453
AB  - We study the impact of plasmon-phonon hybridization on the stopping and image forces acting on a charged particle moving parallel to a graphene-Al2O3-graphene sandwichlike composite system by considering a broad domain in the parameter space. The effective dielectric function of the system is obtained using two descriptions of the electronic response of doped graphene: an ab initio method based on the time-dependent density functional theory calculations and an analytical expression based on the massless Dirac fermion (MDF) approximation for graphene π bands. It is found that the main discrepancies between the two methods come from the high-energy interband electron transitions, which are included in the ab initio method but not in the MDF method. Special attention is paid to the regime of low-particle speeds, where the MDF method compares well with the ab initio method, but the modeling is sensitive to the effects of finite temperature and the treatment of phenomenological damping. It is observed at low particle speeds that both forces exhibit an interesting interplay between the hybrid modes of the phononic type and the continuum of the intraband electron-hole excitations in graphene. Furthermore, the effects of the lowest-energy antisymmetric modes, which exhibit acoustic dispersions at long wavelengths in a system with equally doped graphene layers, are exposed in calculations of the stopping force on a co-moving pair of incident particles with opposite charges that are symmetrically positioned around the target system.
T2  - Physical Review B
T1  - Stopping and image forces acting on a charged particle moving near a graphene-Al2O3-graphene heterostructure
VL  - 106
IS  - 11
SP  - 115430
DO  - 10.1103/PhysRevB.106.115430
ER  - 

@article{
author = "Kalinić, Ana and Despoja, Vito and Radović, Ivan and Karbunar, Lazar and Mišković, Zoran L.",
year = "2022",
abstract = "We study the impact of plasmon-phonon hybridization on the stopping and image forces acting on a charged particle moving parallel to a graphene-Al2O3-graphene sandwichlike composite system by considering a broad domain in the parameter space. The effective dielectric function of the system is obtained using two descriptions of the electronic response of doped graphene: an ab initio method based on the time-dependent density functional theory calculations and an analytical expression based on the massless Dirac fermion (MDF) approximation for graphene π bands. It is found that the main discrepancies between the two methods come from the high-energy interband electron transitions, which are included in the ab initio method but not in the MDF method. Special attention is paid to the regime of low-particle speeds, where the MDF method compares well with the ab initio method, but the modeling is sensitive to the effects of finite temperature and the treatment of phenomenological damping. It is observed at low particle speeds that both forces exhibit an interesting interplay between the hybrid modes of the phononic type and the continuum of the intraband electron-hole excitations in graphene. Furthermore, the effects of the lowest-energy antisymmetric modes, which exhibit acoustic dispersions at long wavelengths in a system with equally doped graphene layers, are exposed in calculations of the stopping force on a co-moving pair of incident particles with opposite charges that are symmetrically positioned around the target system.",
journal = "Physical Review B",
title = "Stopping and image forces acting on a charged particle moving near a graphene-Al2O3-graphene heterostructure",
volume = "106",
number = "11",
pages = "115430",
doi = "10.1103/PhysRevB.106.115430"
}

Kalinić, A., Despoja, V., Radović, I., Karbunar, L.,& Mišković, Z. L.. (2022). Stopping and image forces acting on a charged particle moving near a graphene-Al2O3-graphene heterostructure. in Physical Review B, 106(11), 115430.
https://doi.org/10.1103/PhysRevB.106.115430

Kalinić A, Despoja V, Radović I, Karbunar L, Mišković ZL. Stopping and image forces acting on a charged particle moving near a graphene-Al2O3-graphene heterostructure. in Physical Review B. 2022;106(11):115430.
doi:10.1103/PhysRevB.106.115430 .

Kalinić, Ana, Despoja, Vito, Radović, Ivan, Karbunar, Lazar, Mišković, Zoran L., "Stopping and image forces acting on a charged particle moving near a graphene-Al2O3-graphene heterostructure" in Physical Review B, 106, no. 11 (2022):115430,
https://doi.org/10.1103/PhysRevB.106.115430 . .

TY  - JOUR
AU  - Kalinić, Ana
AU  - Radović, Ivan
AU  - Karbunar, Lazar
AU  - Despoja, Vito
AU  - Mišković, Zoran L.
PY  - 2021
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/11685
AB  - We study the wake effect in a graphene-Al2O3-graphene composite system induced by an external charged particle moving parallel to it by using the dynamic polarization function of graphene within the random phase approximation for its π electrons described as Dirac's fermions and by using a local dielectric function for the bulk sapphire (aluminum oxide, Al2O3). We explore the effects of variation of the particle speed, its distance from the top graphene layer, the thickness of the Al2O3 layer, the damping rate of plasmons in graphene, and the doping density (i.e., Fermi energy) of graphene on the wake potential. For the velocity of the charged particle below the threshold for excitations of the Dirac plasmon in graphene, given by its Fermi velocity , strong effects are observed due to variation of the particle distance, while for the velocity of the charged particle above strong effects are observed due to varying the thickness of the Al2O3 layer, as well as due to plasmon damping of graphene's π electrons, and graphene doping.
T2  - Physica E: Low-dimensional Systems and Nanostructures
T1  - Wake effect in interactions of ions with graphene-sapphire-graphene composite system
VL  - 126
SP  - 114447
DO  - 10.1016/j.physe.2020.114447
ER  - 

@article{
author = "Kalinić, Ana and Radović, Ivan and Karbunar, Lazar and Despoja, Vito and Mišković, Zoran L.",
year = "2021",
abstract = "We study the wake effect in a graphene-Al2O3-graphene composite system induced by an external charged particle moving parallel to it by using the dynamic polarization function of graphene within the random phase approximation for its π electrons described as Dirac's fermions and by using a local dielectric function for the bulk sapphire (aluminum oxide, Al2O3). We explore the effects of variation of the particle speed, its distance from the top graphene layer, the thickness of the Al2O3 layer, the damping rate of plasmons in graphene, and the doping density (i.e., Fermi energy) of graphene on the wake potential. For the velocity of the charged particle below the threshold for excitations of the Dirac plasmon in graphene, given by its Fermi velocity , strong effects are observed due to variation of the particle distance, while for the velocity of the charged particle above strong effects are observed due to varying the thickness of the Al2O3 layer, as well as due to plasmon damping of graphene's π electrons, and graphene doping.",
journal = "Physica E: Low-dimensional Systems and Nanostructures",
title = "Wake effect in interactions of ions with graphene-sapphire-graphene composite system",
volume = "126",
pages = "114447",
doi = "10.1016/j.physe.2020.114447"
}

Kalinić, A., Radović, I., Karbunar, L., Despoja, V.,& Mišković, Z. L.. (2021). Wake effect in interactions of ions with graphene-sapphire-graphene composite system. in Physica E: Low-dimensional Systems and Nanostructures, 126, 114447.
https://doi.org/10.1016/j.physe.2020.114447

Kalinić A, Radović I, Karbunar L, Despoja V, Mišković ZL. Wake effect in interactions of ions with graphene-sapphire-graphene composite system. in Physica E: Low-dimensional Systems and Nanostructures. 2021;126:114447.
doi:10.1016/j.physe.2020.114447 .

Kalinić, Ana, Radović, Ivan, Karbunar, Lazar, Despoja, Vito, Mišković, Zoran L., "Wake effect in interactions of ions with graphene-sapphire-graphene composite system" in Physica E: Low-dimensional Systems and Nanostructures, 126 (2021):114447,
https://doi.org/10.1016/j.physe.2020.114447 . .

TY  - JOUR
AU  - Despoja, Vito
AU  - Radović, Ivan
AU  - Politano, Antonio
AU  - Mišković, Zoran L.
PY  - 2020
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/8953
AB  - The excitation spectrum in the region of the intraband (Dirac plasmon) and interband ( π plasmon) plasmons in graphene/Pt-skin terminated Pt 3 Ni(111) is reproduced by using an ab-initio method and an empirical model. The results of both methods are compared with experimental data. We discover that metallic screening by the Pt layer converts the square-root dispersion of the Dirac plasmon into a linear acoustic-like plasmon dispersion. In the long-wavelength limit, the Pt d electron excitations completely quench the π plasmon in graphene at about 4.1 eV, that is replaced by a broad peak at about 6 eV. Owing to a rather large graphene/Pt-skin separation (≈3.3 Å), the graphene/Pt-skin hybridization becomes weak at larger wave vectors, so that the π plasmon is recovered with a dispersion as in a free-standing graphene.
T2  - Nanomaterials
T1  - Insights on the Excitation Spectrum of Graphene Contacted with a Pt Skin
VL  - 10
IS  - 4
SP  - 703
DO  - 10.3390/nano10040703
ER  - 

@article{
author = "Despoja, Vito and Radović, Ivan and Politano, Antonio and Mišković, Zoran L.",
year = "2020",
abstract = "The excitation spectrum in the region of the intraband (Dirac plasmon) and interband ( π plasmon) plasmons in graphene/Pt-skin terminated Pt 3 Ni(111) is reproduced by using an ab-initio method and an empirical model. The results of both methods are compared with experimental data. We discover that metallic screening by the Pt layer converts the square-root dispersion of the Dirac plasmon into a linear acoustic-like plasmon dispersion. In the long-wavelength limit, the Pt d electron excitations completely quench the π plasmon in graphene at about 4.1 eV, that is replaced by a broad peak at about 6 eV. Owing to a rather large graphene/Pt-skin separation (≈3.3 Å), the graphene/Pt-skin hybridization becomes weak at larger wave vectors, so that the π plasmon is recovered with a dispersion as in a free-standing graphene.",
journal = "Nanomaterials",
title = "Insights on the Excitation Spectrum of Graphene Contacted with a Pt Skin",
volume = "10",
number = "4",
pages = "703",
doi = "10.3390/nano10040703"
}

Despoja, V., Radović, I., Politano, A.,& Mišković, Z. L.. (2020). Insights on the Excitation Spectrum of Graphene Contacted with a Pt Skin. in Nanomaterials, 10(4), 703.
https://doi.org/10.3390/nano10040703

Despoja V, Radović I, Politano A, Mišković ZL. Insights on the Excitation Spectrum of Graphene Contacted with a Pt Skin. in Nanomaterials. 2020;10(4):703.
doi:10.3390/nano10040703 .

Despoja, Vito, Radović, Ivan, Politano, Antonio, Mišković, Zoran L., "Insights on the Excitation Spectrum of Graphene Contacted with a Pt Skin" in Nanomaterials, 10, no. 4 (2020):703,
https://doi.org/10.3390/nano10040703 . .

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  - 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  - 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  - 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 .

TY  - CONF
AU  - Despoja, Vito
AU  - Radović, Ivan
AU  - Mišković, Zoran
PY  - 2016
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/12646
AB  - Nowadays we are witnesses of a development of one promising branch of applied physics, called plasmonics. Especially interesting issue is plasmonics in quasi-two-dimensional (q2D) crystals deposited on various dielectric substrates. Here arise the main questions: how to increase the 2D plasmon propagation length and how to excite 2D plasmon most efficiently. We will focus on describing the interaction between electronic excitations in two graphene layers with phonons in aluminium oxide (Al2O3) slab on which the graphene layers are deposited. Special attention will be paid to explain the hybridization between 2D plasmons and surface (TO) phonons. Because of multiple intersections of 2D plasmons and TO phonons the 2D plasmon moves to lower energies which allows it to be excited by charged particles moving at subthreshold speeds, 􀝒 􀵏 􀝒􀮿 [1]. We will present the results for wake potential induced by a charged particle which moves parallel to the graphene/dielectric interface. It will be shown how various substrates modify the efficiency of particle/plasmon coupling. The electronic excitations in graphene are obtained by using plane waveab initio approach where we have addressed the problem of calculation of EELS spectra in the optical limit (􀜳 → 0) and how to avoid intersupercell Coulomb interaction [2].
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  - Interactions of charged particles with double-layer graphene
SP  - 137
EP  - 137
UR  - https://hdl.handle.net/21.15107/rcub_vinar_12646
ER  - 

@conference{
author = "Despoja, Vito and Radović, Ivan and Mišković, Zoran",
year = "2016",
abstract = "Nowadays we are witnesses of a development of one promising branch of applied physics, called plasmonics. Especially interesting issue is plasmonics in quasi-two-dimensional (q2D) crystals deposited on various dielectric substrates. Here arise the main questions: how to increase the 2D plasmon propagation length and how to excite 2D plasmon most efficiently. We will focus on describing the interaction between electronic excitations in two graphene layers with phonons in aluminium oxide (Al2O3) slab on which the graphene layers are deposited. Special attention will be paid to explain the hybridization between 2D plasmons and surface (TO) phonons. Because of multiple intersections of 2D plasmons and TO phonons the 2D plasmon moves to lower energies which allows it to be excited by charged particles moving at subthreshold speeds, 􀝒 􀵏 􀝒􀮿 [1]. We will present the results for wake potential induced by a charged particle which moves parallel to the graphene/dielectric interface. It will be shown how various substrates modify the efficiency of particle/plasmon coupling. The electronic excitations in graphene are obtained by using plane waveab initio approach where we have addressed the problem of calculation of EELS spectra in the optical limit (􀜳 → 0) and how to avoid intersupercell Coulomb interaction [2].",
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 = "Interactions of charged particles with double-layer graphene",
pages = "137-137",
url = "https://hdl.handle.net/21.15107/rcub_vinar_12646"
}

Despoja, V., Radović, I.,& Mišković, Z.. (2016). Interactions of charged particles with double-layer 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., 137-137.
https://hdl.handle.net/21.15107/rcub_vinar_12646

Despoja V, Radović I, Mišković Z. Interactions of charged particles with double-layer 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;:137-137.
https://hdl.handle.net/21.15107/rcub_vinar_12646 .

Despoja, Vito, Radović, Ivan, Mišković, Zoran, "Interactions of charged particles with double-layer 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):137-137,
https://hdl.handle.net/21.15107/rcub_vinar_12646 .