| 1. |
- Benhouria, Y., et al.
(författare)
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Quantum Monte Carlo study of dynamic magnetic properties of nano-graphene
- 2018
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Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 460, s. 223-228
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Tidskriftsartikel (refereegranskat)abstract
- Using the Quantum Monte Carlo simulation (QMCS), the dynamic blocking temperature of a nanographene bilayer has been investigated within the framework of the Transverse Ising Model (TIM) with mixed spins, under the existence of the time-dependent oscillating longitudinal magnetic field (h(t) = h(b) + h(0)cos(omega t)) and the transverse field (Omega). The influence of the time-dependent oscillating longitudinal magnetic field, the period of magnetic field (tau) and the transverse field (Omega) on the thermal behavior of the total longitudinal and transverse dynamic order parameters, the total dynamic magnetic susceptibility and the dynamic hysteresis of the nano-graphene bilayer are also studied. As results, we remark the appearance of multiple hysteresis loops and the system exhibits the superparamagnetic behavior at the dynamic blocking temperature.
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| 2. |
- Bouziani, I., et al.
(författare)
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Ab initio study of electronic and optical properties of penta-SiC2 and-SiGeC4 monolayers for solar energy conversion
- 2020
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Ingår i: Superlattices and Microstructures. - : ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD. - 0749-6036 .- 1096-3677. ; 142
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Tidskriftsartikel (refereegranskat)abstract
- In the current study, we explore theoretically electronic and optical properties of penta-SiC2 and -SiGeC4 monolayers based on ab initio computations and utilizing modified Becke-Johnson generalized gradient-approximation (mBJ-GGA) within the density functional theory. The calculated results show that both 2D penta-SiC2 and -SiGeC4 are structurally stable, according to their negative formation energy. Furthermore, we have found that the penta-SiC2 and -SiGeC4 semiconductors show indirect and moderate band gaps of 1.75 and 1.62 eV by employing mBJGGA functional, respectively. Also, these systems present sigma- and pi-bond between two nearest neighbor carbon atoms by overlapping sp(2)-sp(2) and p-p orbitals, respectively, as well as an ionic bond between two nearest neighbor Si-C and Ge-C atoms. Additionally, we have shown that the considered compounds exhibit small reflectivity and high absorption peaks in visible region with the shift of absorption edge of 2D penta-SiGeC4 to the low energy visible region due to its small band gap compared to that of 2D penta-SiC2. These findings make both penta-SiC2 and -SiGeC4 monolayer semiconductors promising candidates for photovoltaic technology.
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| 3. |
- Bouziani, I., et al.
(författare)
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Electronic, optical and thermoelectric properties of two-dimensional pentagonal SiGeC4 nanosheet for photovoltaic applications : First-principles calculations
- 2021
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Ingår i: Superlattices and Microstructures. - : Elsevier. - 0749-6036 .- 1096-3677. ; 158
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Tidskriftsartikel (refereegranskat)abstract
- In this theoretical study, based on the density functional theory, we investigate the electronic, optical and thermoelectric properties of SiGeC4 nanosheet, within the framework of mBJ-GGA approximation (modified Becke-Johnson generalized gradient approximation). The calculated results indicate that the two-dimensional SiGeC4 compound is energetically, dynamically, thermally and mechanically stable in the pentagonal structure and shows semiconductor character with indirect and moderate bandgap. Also, it is found that this two-dimensional system presents high absorption and low reflectivity as well as high photoconductivity in the visible range. Furthermore, it is shown that the studied compound exhibits good thermoelectric performance with high electrical conductivity and Seebeck coefficient. These results render the twodimensional pentagonal SiGeC4 nanosheet as strong absorber layer candidate in the next generation of photovoltaic devices.
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| 4. |
- Bouziani, I, et al.
(författare)
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Half metallic ferromagnetic behavior in (Ga, Cr)N and (Ga, Cr, V)N compounds for spintronic technologies : Ab initio and Monte Carlo methods
- 2019
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Ingår i: Journal of Magnetism and Magnetic Materials. - : Elsevier BV. - 0304-8853 .- 1873-4766. ; 477, s. 220-225
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Tidskriftsartikel (refereegranskat)abstract
- In this article, we investigate the magnetic and electronic properties of GaN doped with simple and double impurities utilizing Ab initio and Monte Carlo studies. We have predicted that (Ga, Cr)N and (Ga, Cr, V)N compounds exhibit ferromagnetic- and halfmetallic-behavior with 100% spin polarization at the Fermi level. Moreover, we have found that Ga1-xCrxN and Ga1-2xCrxVxN (x = 0.04, 0.05 and 0.06) show a second order ferromagnetic transition and that their T-c is above room temperature. These predictions make (Ga, Cr)N and (Ga, Cr, V)N compounds strong candidates for spintronic technologies.
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| 5. |
- Bouziani, I, et al.
(författare)
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High Curie temperature in halfmetallic ferromagnets (Zn, Cr, Ti)Se and (Zn, Cr, Ti)Te for spintronic devices : Ab initio and Monte Carlo treatments
- 2020
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Ingår i: Materials Science & Engineering. - : ELSEVIER. - 0921-5107 .- 1873-4944. ; 253
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Tidskriftsartikel (refereegranskat)abstract
- The current study is purposed to investigate the magnetic- and electronic-properties of Zn1-2xCrxTixSe and Zn1-2xCrxTixTe systems by means of Ab initio and Monte Carlo calculations. We have predicted that the two systems show ferromagnetic halfmetallic behavior with 100% spin polarization at the Fermi level and their ferromagnetic stability is attributed to the double exchange coupling. Our calculations suggest further that these compounds exhibit a 2nd order ferromagnetic transition with high Curie temperature. Thus, (Zn, Cr, Ti)Se and (Zn, Cr, Ti)Te compounds are strong candidates for spintronic devices, especially for magnetic random access memories (MRAM) based on the spin transfer torque.
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| 6. |
- Bouziani, I., et al.
(författare)
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Magnetoelectronic properties of GaN codoped with (V, Mn) impurities for spintronic devices : Ab-initio and Monte Carlo studies
- 2018
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Ingår i: Physica A. - : ELSEVIER SCIENCE BV. - 0378-4371 .- 1873-2119. ; 512, s. 1249-1259
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Tidskriftsartikel (refereegranskat)abstract
- In this work, we investigate the Magnetoelectronic properties of (V, Mn) codoped GaN using first principles calculations (FPCs) for the spintronic applications. We have obtained the ferromagnetic behavior in (Ga, V)N codoped with Mn atoms, which is believed to be caused by the double exchange mechanism. Moreover, it is observed that our system is halfmetallic at the Fermi level, with 100% spin polarization. The total magnetic moment of (V, Mn) codoped GaN is mainly originated from the V and Mn atoms, and the magnetic moment of V impurities rises with the concentration of V atoms while keeping constant that of the Mn atoms. In addition to that, the exchange coupling is obtained from FPCs and using the Ising model. The Monte Carlo method founded on the Heat Bath algorithm support our FPCs, by investigating the influence of the addition of Mn impurities to (Ga, V)N compound on the critical temperature T-C(MC), the magnetization per site M, the magnetic susceptibility chi and the specific heat C-V. We have found that T-C(MC) is above room temperature as well as the stability of the ferromagnetic state in (Ga, V)N becomes more important after the inclusion of the Manganese.
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| 7. |
- Bouziani, I., et al.
(författare)
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Magnetoelectronic properties of Vanadium impurities co-doped (Cd, Cr)Te compound for spintronic devices : First principles calculations and Monte Carlo simulation
- 2018
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Ingår i: Journal of Magnetism and Magnetic Materials. - : ELSEVIER SCIENCE BV. - 0304-8853 .- 1873-4766. ; 466, s. 420-429
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Tidskriftsartikel (refereegranskat)abstract
- We have applied the first-principles calculations to investigate magnetoelectronic properties of Vanadium impurities co-doped (Cd, Cr)Te compound for spintronic devices. The ferromagnetic (FM) nature in (Cd, Cr)Te compound co-doped with V atoms has been found, and the mechanism responsible for this behavior has been considered to be the double exchange. Moreover, the Curie-temperature calculation reveals that the stability's field of the FM-phase rises with rising both the concentration of Cr and V atoms above ambient temperature. This system presents the half-metallic character where its polarization of spin is total at the Fermi level, and its total magnetic moment is principally induced by Cr and V elements. The spin-orbit coupling (SOC) typically play an important role in the electronic structure calculations due to both the concentration of Cr and V impurities. In addition to that, our results have been confirmed by the calculation of magnetization and susceptibility using the Monte Carlo simulation.
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| 8. |
- Bouziani, I., et al.
(författare)
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Two-dimensional Janus Sn2SSe and SnGeS2 semiconductors as strong absorber candidates for photovoltaic solar cells : First principles computations
- 2021
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Ingår i: Physica. E, Low-Dimensional systems and nanostructures. - : Elsevier. - 1386-9477 .- 1873-1759. ; 134
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Tidskriftsartikel (refereegranskat)abstract
- Two-dimensional materials provide new opportunities for the next generation of effective and ultrathin photovoltaic solar cells. Herein, we propose Janus monolayers of Tin monochalcogenides, especially Janus Sn2SSe (type TA) and SnGeS2 (type TB) nanosheets, as strong absorber candidates for solar energy conversion, referring to their excellent electronic and optical properties. Interestingly, based on the first-principles computations, both Janus Sn2SSe and SnGeS2 monolayers possess semiconductor character with indirect and moderate band gaps of 1.60 and 1.61 eV, respectively. Accordingly, the considered systems, Sn2SSe and SnGeS2 single-layers, have high absorption coefficient, reaching up to 49.7 and 62.5 mu m(-1), high optical conductivity of about 4513 and 3559 Omega(-1)cm(-1), as well as low reflectivity never exceed 34.6 and 38.5 % in visible region, respectively. Additionally, the maximum photovoltaic efficiency of single-junction solar cells based on SnGeS2 and Sn2SSe nanosheets can reach as high as 27.47 % and 28.12 %, respectively. The present outstanding results would motivate both theoretical and experimental researchers to deepen the study of the potential applications of twodimensional Janus materials based on Tin monochalcogenides in solar cell technology.
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| 9. |
- Chafai, A., et al.
(författare)
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First-principles insights into the optical and electronic characteristics of barium intercalated AB-stacked bilayer graphene
- 2023
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Ingår i: The European Physical Journal Plus. - : Springer Nature. - 2190-5444. ; 138:8
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Tidskriftsartikel (refereegranskat)abstract
- The present study describes the electronic and optical characteristics of barium atoms (an alkaline earth metal) intercalated within AB-stacked bilayer graphene (AB-2LG). Using state-of-the-art first-principles computations and taking into account the dispersion forces between the diverse nanosheets, we determined that the intercalation of barium atoms (Ba) into AB-2LG increases the interlayer distance from 3.357 to 5.584 degrees A, and no C-Ba bond formation has been observed. In addition, our findings reveal that the presence of Ba atoms inside the AB-2LG induces a change in the Space group number from 164 (pure AB-2LG) to 156 (Ba-intercalated AB-2LG). Concurrently, we observed that the AB-2LG band structure exhibits a Dirac cone at the K-point, which is a characteristic signature of a semi-metallic character. By contrast, the electronic behavior of the barium-intercaled AB-2LG is found to be metallic. Also, we noticed that the confinement of Ba atoms into the AB-2LG shifts the Dirac point under the Fermi level. Additionally, upon examining the optical properties under the 001 and 100-polarization of the incident light, we found that all optical parameters of both under-investigated bidimensional materials exhibit an anisotropic character. Interestingly, under the 001-polarization, we observed that the intercalation of AB-2LG with Ba atoms reduces the optical absorption to zero in the visible region, and blueshifts are the absorption peak observed in the infrared region. Furthermore, in the case of 001-polarization, the presence of Ba atoms enhances the optical absorption in the 7-9 eV spectral range. However, the obtained data exhibit a remarkable decrease in the refractive index after the Ba intercalation process, for both considered polarization directions.
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| 10. |
- Haman, Z., et al.
(författare)
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Structural, electronic and optical properties of two-dimensional Janus transition metal oxides MXO (M = Ti, Hf and Zr; X = S and Se) for photovoltaic and opto-electronic applications
- 2021
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Ingår i: Physica. B, Condensed matter. - : Elsevier. - 0921-4526 .- 1873-2135. ; 604
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Tidskriftsartikel (refereegranskat)abstract
- Two-dimensional Janus transition metal dichalcogenides structures have drawn increasing importance due to their remarkable properties for versatile applications in optoelectronic, photo-catalytic, thermo-electricity, piezoelectricity and spintronic. In this Paper, by employing the Ab-initio computations based on the density functional theory, the structural, electronic and optical properties of Janus MXO (M = Ti, Hf and Zr; X = S and Se) mono-layers are investigated utilizing full potential linearized augmented plane waves (FP-LAPW) method. The lattice parameters of the six Janus were computed, which are close to the previous theoretical results. The density of states and the electronic band structures were investigated for the first time using (GGA-PBE) approximation for the potential of the exchange and correlation. The optical parameters like complex dielectric function, refractive index, reflectivity, extinction and absorption coefficients of all Janus were performed. Our results reveal strong absorption coefficient and low reflectivity in the visible and ultraviolet regions, which make them candidates for opto-electronic and photovoltaic applications.
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