TY  - JOUR
AU  - Topalović, Dušan
AU  - Arsoski, Vladimir
AU  - Tadić, Milan Ž.
AU  - Peeters, Francois M.
PY  - 2020
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/9616
AB  - We investigate the electron states in double asymmetric HgTe / Cd x Hg 1 - x Te quantum wells grown along the [001] direction. The subbands are computed by means of the envelope function approximation applied to the eight-band Kane k ⋅ p model. The asymmetry of the confining potential of the double quantum wells results in a gap opening, which is absent in the symmetric system where it can only be induced by an applied electric field. The bandgap and the subbands are affected by spin-orbit coupling, which is a consequence of the asymmetry of the confining potential. The electron-like and hole-like states are mainly confined in different quantum wells, and the enhanced hybridization between them opens a spin-dependent hybridization gap at a finite in-plane wavevector. We show that both the ratio of the widths of the two quantum wells and the mole fraction of the C d x H g 1 - x Te barrier control both the energy gap between the hole-like states and the hybridization gap. The energy subbands are shown to exhibit inverted ordering, and therefore, a nontrivial topological phase could emerge in the system. © 2020 Author(s).
T2  - Journal of Applied Physics
T1  - Asymmetric versus symmetric HgTe / Cd x Hg 1 - X Te double quantum wells: Bandgap tuning without electric field
VL  - 128
IS  - 6
DO  - 10.1063/5.0016069
ER  - 

@article{
author = "Topalović, Dušan and Arsoski, Vladimir and Tadić, Milan Ž. and Peeters, Francois M.",
year = "2020",
abstract = "We investigate the electron states in double asymmetric HgTe / Cd x Hg 1 - x Te quantum wells grown along the [001] direction. The subbands are computed by means of the envelope function approximation applied to the eight-band Kane k ⋅ p model. The asymmetry of the confining potential of the double quantum wells results in a gap opening, which is absent in the symmetric system where it can only be induced by an applied electric field. The bandgap and the subbands are affected by spin-orbit coupling, which is a consequence of the asymmetry of the confining potential. The electron-like and hole-like states are mainly confined in different quantum wells, and the enhanced hybridization between them opens a spin-dependent hybridization gap at a finite in-plane wavevector. We show that both the ratio of the widths of the two quantum wells and the mole fraction of the C d x H g 1 - x Te barrier control both the energy gap between the hole-like states and the hybridization gap. The energy subbands are shown to exhibit inverted ordering, and therefore, a nontrivial topological phase could emerge in the system. © 2020 Author(s).",
journal = "Journal of Applied Physics",
title = "Asymmetric versus symmetric HgTe / Cd x Hg 1 - X Te double quantum wells: Bandgap tuning without electric field",
volume = "128",
number = "6",
doi = "10.1063/5.0016069"
}

Topalović, D., Arsoski, V., Tadić, M. Ž.,& Peeters, F. M.. (2020). Asymmetric versus symmetric HgTe / Cd x Hg 1 - X Te double quantum wells: Bandgap tuning without electric field. in Journal of Applied Physics, 128(6).
https://doi.org/10.1063/5.0016069

Topalović D, Arsoski V, Tadić MŽ, Peeters FM. Asymmetric versus symmetric HgTe / Cd x Hg 1 - X Te double quantum wells: Bandgap tuning without electric field. in Journal of Applied Physics. 2020;128(6).
doi:10.1063/5.0016069 .

Topalović, Dušan, Arsoski, Vladimir, Tadić, Milan Ž., Peeters, Francois M., "Asymmetric versus symmetric HgTe / Cd x Hg 1 - X Te double quantum wells: Bandgap tuning without electric field" in Journal of Applied Physics, 128, no. 6 (2020),
https://doi.org/10.1063/5.0016069 . .

TY  - JOUR
AU  - Topalović, Dušan
AU  - Arsoski, Vladimir
AU  - Tadić, Milan Ž.
AU  - Peeters, François M.
PY  - 2019
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/8534
AB  - We investigate the electron states and optical absorption in square- and hexagonal-shaped two-dimensional (2D) HgTe quantum dots and quantum rings in the presence of a perpendicular magnetic field. The electronic structure is modeled by means of the sp3d5s∗ tight-binding method within the nearest-neighbor approximation. Both bulklike and edge states appear in the energy spectrum. The bulklike states in quantum rings exhibit Aharonov-Bohm oscillations in magnetic field, whereas no such oscillations are found in quantum dots, which is ascribed to the different topology of the two systems. When magnetic field varies, all the edge states in square quantum dots appear as quasibands composed of almost fully flat levels, whereas some edge states in quantum rings are found to oscillate with magnetic field. However, the edge states in hexagonal quantum dots are localized like in rings. The absorption spectra of all the structures consist of numerous absorption lines, which substantially overlap even for small line broadening. The absorption lines in the infrared are found to originate from transitions between edge states. It is shown that the magnetic field can be used to efficiently tune the optical absorption of HgTe 2D quantum dot and quantum ring systems. © 2019 American Physical Society.
T2  - Physical Review B
T1  - Confined electron states in two-dimensional HgTe in magnetic field: Quantum dot versus quantum ring behavior
VL  - 100
IS  - 12
SP  - 125304
DO  - 10.1103/PhysRevB.100.125304
ER  - 

@article{
author = "Topalović, Dušan and Arsoski, Vladimir and Tadić, Milan Ž. and Peeters, François M.",
year = "2019",
abstract = "We investigate the electron states and optical absorption in square- and hexagonal-shaped two-dimensional (2D) HgTe quantum dots and quantum rings in the presence of a perpendicular magnetic field. The electronic structure is modeled by means of the sp3d5s∗ tight-binding method within the nearest-neighbor approximation. Both bulklike and edge states appear in the energy spectrum. The bulklike states in quantum rings exhibit Aharonov-Bohm oscillations in magnetic field, whereas no such oscillations are found in quantum dots, which is ascribed to the different topology of the two systems. When magnetic field varies, all the edge states in square quantum dots appear as quasibands composed of almost fully flat levels, whereas some edge states in quantum rings are found to oscillate with magnetic field. However, the edge states in hexagonal quantum dots are localized like in rings. The absorption spectra of all the structures consist of numerous absorption lines, which substantially overlap even for small line broadening. The absorption lines in the infrared are found to originate from transitions between edge states. It is shown that the magnetic field can be used to efficiently tune the optical absorption of HgTe 2D quantum dot and quantum ring systems. © 2019 American Physical Society.",
journal = "Physical Review B",
title = "Confined electron states in two-dimensional HgTe in magnetic field: Quantum dot versus quantum ring behavior",
volume = "100",
number = "12",
pages = "125304",
doi = "10.1103/PhysRevB.100.125304"
}

Topalović, D., Arsoski, V., Tadić, M. Ž.,& Peeters, F. M.. (2019). Confined electron states in two-dimensional HgTe in magnetic field: Quantum dot versus quantum ring behavior. in Physical Review B, 100(12), 125304.
https://doi.org/10.1103/PhysRevB.100.125304

Topalović D, Arsoski V, Tadić MŽ, Peeters FM. Confined electron states in two-dimensional HgTe in magnetic field: Quantum dot versus quantum ring behavior. in Physical Review B. 2019;100(12):125304.
doi:10.1103/PhysRevB.100.125304 .

Topalović, Dušan, Arsoski, Vladimir, Tadić, Milan Ž., Peeters, François M., "Confined electron states in two-dimensional HgTe in magnetic field: Quantum dot versus quantum ring behavior" in Physical Review B, 100, no. 12 (2019):125304,
https://doi.org/10.1103/PhysRevB.100.125304 . .

TY  - CONF
AU  - Topalović, Dušan
AU  - Arsoski, Vladimir
AU  - Tadić, Milan Ž.
AU  - Peeters, François M.
PY  - 2019
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/11878
AB  - The quantum spin Hall (QSH) effect is a unique phase of matter characterized by a pair of helical edge states protected by time-reversal symmetry. The existence of this phase was first theoretically proposed for graphene [1]. However, experiments showed that spin-orbit interaction in low-mass C atoms is too small to open an energy gap [2]. Therefore, greater attention is paid to materials that are composed of heavier atoms in which relativistic effects are more pronounced. A notable example is thin HgTe/CdTe quantum well (QW) where the QSH effect was theoretically predicted [3] and experimentally realized [4]. By using effective models it has been found that double symmetric HgTe/CdxHg1-xTe QW may also possess a topological nontrivial phase [5, 6]. Structures of this type exhibit interesting 3/2 pseudospin based physics similar to that in bilayer graphene without valley degeneracy [6]. We investigate the electronic properties of double asymmetric HgTe/CdxHg1-xTe QW with [001] orientation. The electronic structure is calculated within the framework of the Kane k · p theory [7]. We choose the common eight-band basis set that describes the coupling between the Γ6, Γ7, and Γ8 bands. We assumed that the model parameters change abruptly along the structure. Also, the difference between the valence bands in HgTe and CdTe is assumed to vary linearly with mole fraction. The theoretical model is based on the Burt envelope function approach on expansion in plane waves is used in our numerical calculations. The results obtained for the electronic structure indicate that a quantum phase transition can occur in asymmetric double QW when a perpendicular electric field is applied. Besides an external field the phase transition could be controlled by varying geometric parameters of the wells and the mole fraction in barriers.
PB  - Belgrade : Vinča Institute of Nuclear Sciences, University of Belgrade
C3  - PHOTONICA2019 : 7th International School and Conference on Photonics & Machine Learning with Photonics Symposium : Book of abstracts
T1  - Tunable quantum phase transitions in asymmetric HgTe/CdxHg1-xTe double quantum wells
SP  - 109
EP  - 109
UR  - https://hdl.handle.net/21.15107/rcub_vinar_11878
ER  - 

@conference{
author = "Topalović, Dušan and Arsoski, Vladimir and Tadić, Milan Ž. and Peeters, François M.",
year = "2019",
abstract = "The quantum spin Hall (QSH) effect is a unique phase of matter characterized by a pair of helical edge states protected by time-reversal symmetry. The existence of this phase was first theoretically proposed for graphene [1]. However, experiments showed that spin-orbit interaction in low-mass C atoms is too small to open an energy gap [2]. Therefore, greater attention is paid to materials that are composed of heavier atoms in which relativistic effects are more pronounced. A notable example is thin HgTe/CdTe quantum well (QW) where the QSH effect was theoretically predicted [3] and experimentally realized [4]. By using effective models it has been found that double symmetric HgTe/CdxHg1-xTe QW may also possess a topological nontrivial phase [5, 6]. Structures of this type exhibit interesting 3/2 pseudospin based physics similar to that in bilayer graphene without valley degeneracy [6]. We investigate the electronic properties of double asymmetric HgTe/CdxHg1-xTe QW with [001] orientation. The electronic structure is calculated within the framework of the Kane k · p theory [7]. We choose the common eight-band basis set that describes the coupling between the Γ6, Γ7, and Γ8 bands. We assumed that the model parameters change abruptly along the structure. Also, the difference between the valence bands in HgTe and CdTe is assumed to vary linearly with mole fraction. The theoretical model is based on the Burt envelope function approach on expansion in plane waves is used in our numerical calculations. The results obtained for the electronic structure indicate that a quantum phase transition can occur in asymmetric double QW when a perpendicular electric field is applied. Besides an external field the phase transition could be controlled by varying geometric parameters of the wells and the mole fraction in barriers.",
publisher = "Belgrade : Vinča Institute of Nuclear Sciences, University of Belgrade",
journal = "PHOTONICA2019 : 7th International School and Conference on Photonics & Machine Learning with Photonics Symposium : Book of abstracts",
title = "Tunable quantum phase transitions in asymmetric HgTe/CdxHg1-xTe double quantum wells",
pages = "109-109",
url = "https://hdl.handle.net/21.15107/rcub_vinar_11878"
}

Topalović, D., Arsoski, V., Tadić, M. Ž.,& Peeters, F. M.. (2019). Tunable quantum phase transitions in asymmetric HgTe/CdxHg1-xTe double quantum wells. in PHOTONICA2019 : 7th International School and Conference on Photonics & Machine Learning with Photonics Symposium : Book of abstracts
Belgrade : Vinča Institute of Nuclear Sciences, University of Belgrade., 109-109.
https://hdl.handle.net/21.15107/rcub_vinar_11878

Topalović D, Arsoski V, Tadić MŽ, Peeters FM. Tunable quantum phase transitions in asymmetric HgTe/CdxHg1-xTe double quantum wells. in PHOTONICA2019 : 7th International School and Conference on Photonics & Machine Learning with Photonics Symposium : Book of abstracts. 2019;:109-109.
https://hdl.handle.net/21.15107/rcub_vinar_11878 .

Topalović, Dušan, Arsoski, Vladimir, Tadić, Milan Ž., Peeters, François M., "Tunable quantum phase transitions in asymmetric HgTe/CdxHg1-xTe double quantum wells" in PHOTONICA2019 : 7th International School and Conference on Photonics & Machine Learning with Photonics Symposium : Book of abstracts (2019):109-109,
https://hdl.handle.net/21.15107/rcub_vinar_11878 .

TY  - CONF
AU  - Topalović, Dušan
AU  - Arsoski, Vladimir
AU  - Čukarić, Nemanja
AU  - Tadić, Milan Ž.
AU  - Peeters, F. M.
PY  - 2017
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/13347
AB  - After decades of applications for photovoltaic devices, HgTe has recently gained popularity due to its unique topological properties. As a matter of fact, HgTe quantum wells host the gapless edge states, which are protected by time reversal symmetry. Those states were predicted by comprehensive theory  [1], which was then confirmed by experiment [2]. In addition to HgTe quantum wells, HgTe quantum dots have been recently explored. Quantum confined states in HgTe colloidal quantum dots [3] were demonstrated to allow for fine tuning of the energy spectra from close to near infrared region [4-6].  We investigate the electronic and optical properties of square shaped HgTe quantum dots. The electronic structure is calculated by means of the nearest neighbour tight binding (TB) method in a sp3d5s*basis where spin-orbit coupling is included [7]. A large number of hopping parameters is taken into account with the aim to accurately describe invertedband structure. The exciton states are modelled as the first-order corrections of the single particle spectra due to the Coulomb and exchange interactions [8]. The dipole moment is determined by including only the intraorbital terms, which was previously demonstrated to be a reasonable approximation for graphene, silicene, and phosphorene quantum dots [9,10]. And the appearance of trivial edge states is avoided by removing the dangling bonds from the quantum dot. The result of this study is that the peculiar edge states exist in square HgTe quantum dots. Furthermore, influence of in-plane electric field and perpendicular magnetic field on the optical absorption spectra is investigated. The edge and bulk states are found to behave differently in external fields, and those differences are explored and analyzed in detail.
PB  - Belgrade : Institute of Physics Belgrade
C3  - PHOTONICA2017 : 6th International School and Conference on Photonics and COST actions: MP1406 and MP1402 : Program and the book of abstracts
T1  - Electronic and optical properties of square HgTe quantum dots
SP  - 98
EP  - 98
UR  - https://hdl.handle.net/21.15107/rcub_vinar_13347
ER  - 

@conference{
author = "Topalović, Dušan and Arsoski, Vladimir and Čukarić, Nemanja and Tadić, Milan Ž. and Peeters, F. M.",
year = "2017",
abstract = "After decades of applications for photovoltaic devices, HgTe has recently gained popularity due to its unique topological properties. As a matter of fact, HgTe quantum wells host the gapless edge states, which are protected by time reversal symmetry. Those states were predicted by comprehensive theory  [1], which was then confirmed by experiment [2]. In addition to HgTe quantum wells, HgTe quantum dots have been recently explored. Quantum confined states in HgTe colloidal quantum dots [3] were demonstrated to allow for fine tuning of the energy spectra from close to near infrared region [4-6].  We investigate the electronic and optical properties of square shaped HgTe quantum dots. The electronic structure is calculated by means of the nearest neighbour tight binding (TB) method in a sp3d5s*basis where spin-orbit coupling is included [7]. A large number of hopping parameters is taken into account with the aim to accurately describe invertedband structure. The exciton states are modelled as the first-order corrections of the single particle spectra due to the Coulomb and exchange interactions [8]. The dipole moment is determined by including only the intraorbital terms, which was previously demonstrated to be a reasonable approximation for graphene, silicene, and phosphorene quantum dots [9,10]. And the appearance of trivial edge states is avoided by removing the dangling bonds from the quantum dot. The result of this study is that the peculiar edge states exist in square HgTe quantum dots. Furthermore, influence of in-plane electric field and perpendicular magnetic field on the optical absorption spectra is investigated. The edge and bulk states are found to behave differently in external fields, and those differences are explored and analyzed in detail.",
publisher = "Belgrade : Institute of Physics Belgrade",
journal = "PHOTONICA2017 : 6th International School and Conference on Photonics and COST actions: MP1406 and MP1402 : Program and the book of abstracts",
title = "Electronic and optical properties of square HgTe quantum dots",
pages = "98-98",
url = "https://hdl.handle.net/21.15107/rcub_vinar_13347"
}

Topalović, D., Arsoski, V., Čukarić, N., Tadić, M. Ž.,& Peeters, F. M.. (2017). Electronic and optical properties of square HgTe quantum dots. in PHOTONICA2017 : 6th International School and Conference on Photonics and COST actions: MP1406 and MP1402 : Program and the book of abstracts
Belgrade : Institute of Physics Belgrade., 98-98.
https://hdl.handle.net/21.15107/rcub_vinar_13347

Topalović D, Arsoski V, Čukarić N, Tadić MŽ, Peeters FM. Electronic and optical properties of square HgTe quantum dots. in PHOTONICA2017 : 6th International School and Conference on Photonics and COST actions: MP1406 and MP1402 : Program and the book of abstracts. 2017;:98-98.
https://hdl.handle.net/21.15107/rcub_vinar_13347 .

Topalović, Dušan, Arsoski, Vladimir, Čukarić, Nemanja, Tadić, Milan Ž., Peeters, F. M., "Electronic and optical properties of square HgTe quantum dots" in PHOTONICA2017 : 6th International School and Conference on Photonics and COST actions: MP1406 and MP1402 : Program and the book of abstracts (2017):98-98,
https://hdl.handle.net/21.15107/rcub_vinar_13347 .

TY  - JOUR
AU  - Topalović, Dušan
AU  - Arsoski, Vladimir
AU  - Pavlović, Suncan
AU  - Čukarić, Nemanja A. 
AU  - Tadić, Milan Ž.
AU  - Peeters, François M.
PY  - 2016
UR  - https://vinar.vin.bg.ac.rs/handle/123456789/974
AB  - We use the Galerkin approach and the finite-element method to numerically solve the effective-mass Schrodinger equation. The accuracy of the solution is explored as it varies with the range of the numerical domain. The model potentials are those of interdiffused semiconductor quantum wells and axially symmetric quantum wires. Also, the model of a linear harmonic oscillator is considered for comparison reasons. It is demonstrated that the absolute error of the electron ground state energy level exhibits a minimum at a certain domain range, which is thus considered to be optimal. This range is found to depend on the number of mesh nodes N approximately as alpha(0) log(e)(alpha 1) (alpha N-2), where the values of the constants alpha(0), alpha(1), and alpha(2) are determined by fitting the numerical data. And the optimal range is found to be a weak function of the diffusion length. Moreover, it was demonstrated that a domain range adaptation to the optimal value leads to substantial improvement of accuracy of the solution of the Schrodinger equation.
T2  - Communications in Theoretical Physics
T1  - On Improving Accuracy of Finite-Element Solutions of the Effective-Mass Schrodinger Equation for Interdiffused Quantum Wells and Quantum Wires
VL  - 65
IS  - 1
SP  - 105
EP  - 113
UR  - https://hdl.handle.net/21.15107/rcub_vinar_974
ER  - 

@article{
author = "Topalović, Dušan and Arsoski, Vladimir and Pavlović, Suncan and Čukarić, Nemanja A.  and Tadić, Milan Ž. and Peeters, François M.",
year = "2016",
abstract = "We use the Galerkin approach and the finite-element method to numerically solve the effective-mass Schrodinger equation. The accuracy of the solution is explored as it varies with the range of the numerical domain. The model potentials are those of interdiffused semiconductor quantum wells and axially symmetric quantum wires. Also, the model of a linear harmonic oscillator is considered for comparison reasons. It is demonstrated that the absolute error of the electron ground state energy level exhibits a minimum at a certain domain range, which is thus considered to be optimal. This range is found to depend on the number of mesh nodes N approximately as alpha(0) log(e)(alpha 1) (alpha N-2), where the values of the constants alpha(0), alpha(1), and alpha(2) are determined by fitting the numerical data. And the optimal range is found to be a weak function of the diffusion length. Moreover, it was demonstrated that a domain range adaptation to the optimal value leads to substantial improvement of accuracy of the solution of the Schrodinger equation.",
journal = "Communications in Theoretical Physics",
title = "On Improving Accuracy of Finite-Element Solutions of the Effective-Mass Schrodinger Equation for Interdiffused Quantum Wells and Quantum Wires",
volume = "65",
number = "1",
pages = "105-113",
url = "https://hdl.handle.net/21.15107/rcub_vinar_974"
}

Topalović, D., Arsoski, V., Pavlović, S., Čukarić, N. A., Tadić, M. Ž.,& Peeters, F. M.. (2016). On Improving Accuracy of Finite-Element Solutions of the Effective-Mass Schrodinger Equation for Interdiffused Quantum Wells and Quantum Wires. in Communications in Theoretical Physics, 65(1), 105-113.
https://hdl.handle.net/21.15107/rcub_vinar_974

Topalović D, Arsoski V, Pavlović S, Čukarić NA, Tadić MŽ, Peeters FM. On Improving Accuracy of Finite-Element Solutions of the Effective-Mass Schrodinger Equation for Interdiffused Quantum Wells and Quantum Wires. in Communications in Theoretical Physics. 2016;65(1):105-113.
https://hdl.handle.net/21.15107/rcub_vinar_974 .

Topalović, Dušan, Arsoski, Vladimir, Pavlović, Suncan, Čukarić, Nemanja A. , Tadić, Milan Ž., Peeters, François M., "On Improving Accuracy of Finite-Element Solutions of the Effective-Mass Schrodinger Equation for Interdiffused Quantum Wells and Quantum Wires" in Communications in Theoretical Physics, 65, no. 1 (2016):105-113,
https://hdl.handle.net/21.15107/rcub_vinar_974 .