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  - 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 . .