| 1. |
- 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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| 2. |
- Behloul, M., et al.
(författare)
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Theoretical investigation of the electronic and magnetic properties of Zn (Fe, Co) Se : Ab initio calculations and Monte Carlo simulations
- 2019
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Ingår i: Superlattices and Microstructures. - : ACADEMIC PRESS LTD- ELSEVIER SCIENCE LTD. - 0749-6036 .- 1096-3677. ; 127, s. 66-70
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Tidskriftsartikel (refereegranskat)abstract
- On the basis of spin density functional calculation, the electronic and magnetic properties of ZnSe doped with double impurities Zn1-2xFexCoxSe (x = 0.05) are studied using the Korringa-Kohn-Rostoker coherent potential approximation (KKR-CPA) method within the local density approximation (LDA). The half-metallic ferromagnetic nature of (Fe, Co) doped ZnSe is investigated. Therefore the electronic structure and magnetic properties of Zn1-2xFexCoxSe exhibit a half-metallic ferromagnetic character; the stability of ferromagnetic (FM) compared to the disorder local moment (DLM) has been discussed. Our calculation is supported by Monte Carlo simulations (MCS) based on the heat bath algorithm. We have examined the effects of system size L on magnetization, specific heat and magnetic susceptibility. The spin density functional calculation results are in good agreement with the literature, especially for 5% of (Co, Fe) each, which gives the most interesting results.
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| 3. |
- Benhouria, Y., et al.
(författare)
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Dynamic magneto-caloric effect of a C70 fullerene : Dynamic Monte Carlo
- 2019
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Ingår i: Physica. E, Low-Dimensional systems and nanostructures. - : Elsevier BV. - 1386-9477 .- 1873-1759. ; 108, s. 191-196
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Tidskriftsartikel (refereegranskat)abstract
- Using the dynamicMonte Carlo (DMC) simulation, the dynamic magnetocaloric effect of a ferrimagnetic C70 Fullerene-like structure is studied within the dynamic Ising model under of a magnetic (h(t)) field. The influences of the amplitude (h0) and the frequency (ω) of the h(t) magnetic field and bias field (hb) on the thermal behavior of the dynamic order parameter and the dynamic magnetocaloric properties (the dynamic isothermal ΔSiso(T,h(t)) entropy variation and the dynamic ΔTad (T,h(t)) adiabatic variation of temperature), the dynamic specific heat, the dynamic entropy and as well as the dynamic refrigerant capacity (RC(t)) ferrimagnetic C70 Fullerene-like structure are studied. Our results may be a reference for future experiment and theoretical studies of the nano-clusters.
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| 4. |
- Benhouria, Y., et al.
(författare)
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Dynamic magneto-caloric effect of a multilayer nanographene : Dynamic quantum Monte Carlo
- 2019
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Ingår i: Physica. E, Low-Dimensional systems and nanostructures. - : Elsevier BV. - 1386-9477 .- 1873-1759. ; 105, s. 139-145
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Tidskriftsartikel (refereegranskat)abstract
- Using the dynamic quantum Monte Carlo simulation, the dynamic magnetocaloric effect of a ferromagnetic multilayer nanographene (MNG) is studied within the dynamic Ising model under the applied of a time-dependent oscillating (h(t)) magnetic field. The influence of the amplitude h(0) and the period tau of the h(t) and the transverse field Omega on the thermal behavior of the dynamic order parameter and the dynamic magnetocaloric properties (the dynamic isothermal Delta S-T (T, h(t)) entropy change and the dynamic Delta T-ad (T, h(t)) adiabatic change of temperature), the dynamic specific heat, the dynamic entropy and as well as the dynamic relative cooling power (RCP(t)) ferrimagnetic MNG are studied. Our predicted results may be a reference for future experiment and theoretical studies of the nanostructures.
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| 5. |
- Chafai, A., et al.
(författare)
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Binding energy of an exciton in a GaN/AlN nanodot : Role of size and external electric field
- 2019
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Ingår i: Physica. B, Condensed matter. - : Elsevier BV. - 0921-4526 .- 1873-2135. ; 559, s. 23-28
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Tidskriftsartikel (refereegranskat)abstract
- We report the impact of an external electric field on the energy spectrum of an exciton inside a spherical shaped GaN/AlN core/shell nanodot. The modulation of the confined exciton lowest state energy by the nanodot size is also treated. Our theoretical approach, based on a variational calculation, predicts a remarkable decrease in the exciton's energy when the electric field is switched on. Furthermore, our investigation shows that for a fixed nanodot size, the energy redshift is a unique function of the external electric field strength. On the other hand, it was observed that as the nanodot size increases the lowest exciton energy decreases and vice versa.
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| 6. |
- Chafai, A., et al.
(författare)
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Linear and nonlinear optical properties of donors inside a CdSe/ZnTe core/shell nanodot : Role of size modulation
- 2019
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Ingår i: RESULTS IN PHYSICS. - : ELSEVIER. - 2211-3797. ; 14
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Tidskriftsartikel (refereegranskat)abstract
- The optical absorption coefficient (OAC) and the refractive index (RI), related to a confined donor, were theoretically investigated by the mean of the density matrix formalism. In order to obtain the 1s - 1p donor transition energy a variational calculation, within the context of the effective-mass approach, was deployed. Our numerical results exhibit the possibility to modulate the electronic and optical properties of confined donors by tailoring the inner and outer radii of the core/shell heterodot. Further, we have obtained that the nanodot size shrinking leads, for very small values of core radius, to reduce the magnitude of the total absorption coefficient resonance peak. It was also obtained that the resonance peak position of the absorption coefficient is redshifted with increasing the core radius for a fixed shell thickness. The same situation occurs when reducing the thickness of the shell material for a fixed core size.
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| 7. |
- Chafai, A., et al.
(författare)
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Role of a uniform magnetic field on the energy spectrum of a single donor in a core/shell spherical quantum dot
- 2019
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Ingår i: Zhongguó wùli xuékan. - : ELSEVIER SCIENCE BV. - 0577-9073. ; 57, s. 189-194
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Tidskriftsartikel (refereegranskat)abstract
- Using the variational approach within the framework of the effective-mass approximation (EMA), the binding energy of a centred hydrogenic donor impurity in a CdSe/ZnTe core/shell spherical quantum dot (CSSQD) in the presence of an external magnetic field was investigated. In this model, we have taken into account the effect of the radial dependence of the dielectric constant and of the electron effective mass. Our numerical results show a remarkable influence of the nanodot spatial parameters and of the external magnetic field strength on the shallow donor binding energy.
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| 8. |
- Houmad, M., et al.
(författare)
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Improving the electrical conductivity of Siligraphene SiC7 by strain
- 2019
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Ingår i: Optik (Stuttgart). - : Elsevier BV. - 0030-4026 .- 1618-1336. ; 177, s. 118-122
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Tidskriftsartikel (refereegranskat)abstract
- Using the 1st principle calculations founded on Density Functional Theory (DFT), we examined the strain effect of band gap (BG) and electrical property (EP) of Siligraphene (g-SiC7) under biaxial strains (Compressive and tensile) using Generalized Gradient Approximation (GGA). We found that the BG of g-SiC7 was decreasing as function of the strain and we remarked that the electrical conductivity of g-SiC7 under biaxial strains become important of 6% for tension effect. For the compressive, we obtained an increase for all compressive applying, but we remarked the higher and lower values are successively -2% and -6%. Last not least, we deduced that it's possible to increase the electrical conductivity of g-SiC7. Also, this material can be used in solar cell applications and for photo-voltaic (PV) applications as a light donor material.
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