Hakim BAAZIZ - Academia.edu (original) (raw)

Papers by Hakim BAAZIZ

Journal of Superconductivity and Novel Magnetism, 2022

Materials Science in Semiconductor Processing, 2022

Philosophical Magazine, 2021

ABSTRACT The magnetic, structural and optical properties of CoX2O4 (X = Cr, Mn and Fe) spinels ar... more ABSTRACT The magnetic, structural and optical properties of CoX2O4 (X = Cr, Mn and Fe) spinels are calculated using GGA + U approximation. The effect of the octahedral cation X on the properties of these spinels are analyzed. In order to better understand the electronic aspect of these compounds we studied the issue between the relative forces of the exchange effect and the crystal field effect through a complete analysis of the densities of electronic states. Obtaining the correct ground state is only possible if the electron–electron interactions between magnetic cations are introduced. When the X cations are changed, the crystalline structure changes totally from cubic normal spinel for CoFe2O4 to tetragonal normal spinel one for CoMn2O4 to inverse spinel for CoCr2O4 . The electronic properties of our spinels are significantly different, an increase in the band gap from Fe to Mn to Cr compounds is obtained. Magnetic exchange interactions are strongly affected by sub-lattices occupation in the inverse phase of CoFe2O4 and significant structural distortion of the CoMn2O4 compound. The analysis of structural parameters and electronic structures plays a role on the trends of magnetic exchange interactions. We have noticed that the iron states in CoFe2O4 are extremely localised making this spinel very different from the X cation states in the other two spinels. So the variation in X cations allows us to confirm the trend in the properties of CoX2O4. The prediction of optical properties is possible and it allowed us to calculate different optical parameters. We have noticed that decreases with increasing band gap.

Physica Scripta, 2021

We have addressed the several unpublished elastic, mechanical, optical, anisotropic and magnetic ... more We have addressed the several unpublished elastic, mechanical, optical, anisotropic and magnetic properties of V2NiSb inverse Heusler alloy through the density functional theory (DFT) framework. Calculated elastic constants indicate mechanical stability and ductile mechanical character of the alloy. The alloy has high elastic anisotropy. Some optical properties like dielectric function, absorption, reflectance, optical conductivity, etc were also surveyed. According to the obtained results, V2NiSb is a good absorber and high refractive index material in the ultraviolet (UV) region. The magnetic results of the alloy signify typical ferromagnetism with 0.8 μ B total magnetic moment and compares well former findings. Our results may further shed light on the possible experimental researches of V2NiSb alloys for practical applications.

Semiconductor Science and Technology, 2020

We report ab initio investigation of structural, electronic, magnetic and optical properties of N... more We report ab initio investigation of structural, electronic, magnetic and optical properties of NiFe2O4 compound. Hubbard parameters are computed for both Ni and Fe atoms. Employing GGA and GGA+U approximations and taking into consideration four possible types of atomic arrange-ments, we identify the most stable structural-magnetic configuration of the system. Interestingly, the inverse spinel NiFe2O4 compound is found to exhibit a ferrimagnetic structure. The ground state structural lattice parameters and the interatomic distances of spinel NiFe2O4 compound are comput-ed. Furthermore, band structure calculations demonstrate that NiFe2O4 compound exhibits large band gaps in both spins configurations with large magnetic moment. Energetically, Ferrite nickel favors the inverse spinel phase in which Fe and Ni cations in either octahedral or tetrahedral sites adopt the high spin configuration. We found that energy of the normal spinel is higher than that of the inverse spinel confirming that inverse spinel is the most stable structure of NiFe2O4 compound. The optical behavior of NiFe2O4 compound is characterized by calculating the real and imaginary part of the dielectric function, the absorption coefficients, the refractive index, the optical conduc-tivity and the energy loss. Optimizing structural, electronic, magnetic and optical properties of this novel compound is crucial for exploring and utilizing it for modern device applications.

Philosophical Magazine, 2020

The inverse Heusler alloys such as Ti 2 CoSi, Mn 2 CoAl and Cr 2 ZnSi were studied in the framewo... more The inverse Heusler alloys such as Ti 2 CoSi, Mn 2 CoAl and Cr 2 ZnSi were studied in the framework of density functional theory using FP-LAPW linearised augmented plane wave method in order to determine the different physical properties such as structural, electronic, magnetic and thermoelectric. The generalised gradient approximation (GGA) was used to treat the exchange-correlation energy and the Beck-Johnson (mBJ) approach was used to calculate the electronic properties. In all studied compounds, the stable type Hg 2 CuTi was energetically more favourable than Cu 2 MnAl type structure. The results show that two compounds (Ti 2 CoSi and Mn 2 CoAl) are both ferromagnetic (FM) while Cr 2 ZnSi is antiferromagnetic (AFM). The compounds Ti 2 CoSi and Mn 2 CoAl have a total magnetic moment of 3 and 2 μ B, respectively, whereas the Cr 2 ZnSi alloy has a total magnetic moment equals zero. The Ti 2 CoSi, Mn 2 CoAl and Cr 2 ZnSi compounds exhibit halfmetallic (HM) character with 100% spin polarisation at the Fermi level. Finally, the semi-classical Boltzmann theory implicit in the BoltzTraP code was used to calculate the electronic transport coefficients such as thermal and electrical conductivity, the Seebeck coefficient and the factor of merit.

Journal of Magnetism and Magnetic Materials, 2019

Monolayer SnO has attracted extensive attention due to the unique electronic properties, which ha... more Monolayer SnO has attracted extensive attention due to the unique electronic properties, which have potential applications in nanoelectronic and optoelectronic devices. Transition metal (TM) atoms are often used to modulate electronic structures and magnetic properties of two dimensional (2D) materials, which can facilitate the application of these materials in spintronic devices. The electronic structure and magnetic characteristics of 3d TM (TM = Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu and Zn) adsorbed SnO monolayer are predicted by first-principle calculations. The n-type doping in the SnO monolayer appears when Sc, Ti, V, Cr, Mn, Fe and Zn atoms are adsorbed. Co, Ni and Cu adsorptions induce the p-type doping in the SnO monolayer. In addition, the magnetic moments of SnO in the adsorption systems are in the range from −0.038 to 0.414 μ B , and that reach the maximum at the case of Ni-absorbed. It is also found that Fe, Co and Ni adsorbed SnO monolayers have a perpendicular magnetic anisotropy (PMA), while Ti, V, Cr and Mn adsorbed SnO monolayers have an in-plane magnetic anisotropy (IMA). Our results indicate that TM adsorbed SnO monolayers have the potential applications in spintronic devices.

International Journal of Modern Physics B, 2017

The structural, electronic, elastic and thermodynamic properties of Curium Monopnictides CmX (X =... more The structural, electronic, elastic and thermodynamic properties of Curium Monopnictides CmX (X = N, P, As, Sb and Bi) are investigated using first-principles calculations based on the density functional theory (DFT) and full potential linearized augmented plane wave (FP-LAPW) method under ambient condition and high pressure. The exchange-correlation term is treated using two approximations spin-polarized local density approximation (LSDA) and spin-polarized generalized gradient approximation generalized (GGA). The structural parameters such as the equilibrium lattice parameters, bulk modulus and the total energies are calculated in two phases: namely NaCl (B1) and CsCl (B2). The obtained results are compared with the previous theoretical and experimental results. A structural phase transition from B1 phase to B2 phase for Curium pnictides has been obtained. The highest transition pressure is 122 GPa for CmN and the lowest one is 10.0 GPa for CmBi compound. The electronic properties...

Journal of Physics and Chemistry of Solids, 2016

The electronic structure, elastic, and phonon properties of OsM (M=Hf, Ti, Y, and Zr) compounds a... more The electronic structure, elastic, and phonon properties of OsM (M=Hf, Ti, Y, and Zr) compounds are studied using first-principles calculations. Elastic constants of OsY and specific heat capacity of OsM (M= Hf, Ti, Y, and Zr) are reported for the first time. The predicted equilibrium lattice constants are in excellent agreement with experiment. The calculated values of bulk moduli are considerably high but are much smaller than that of Osmium, which is around 400 GPa. The phase stability of the OsM (M=Hf, Ti, Y and Zr) compounds were studied by DOS calculations and the results suggest that OsY is unstable in the B2 phase. The brittleness and ductility properties of OsM (M=Hf, Ti, Y, and Zr) are determined. OsM (M=Hf, Ti, Y, and Zr) compounds are predicted to be ductile materials. The electronic structure and phonon frequency curves of OsM (M=Hf, Ti, Y, and Zr) compounds are obtained. The position of Fermi level of these systems was calculated and discussed in terms of the pseudo gaps. The finite and small DOS at the Fermi level 0.335, 0.375, 1.063, and 0.383 electrons/eV for OsHf, OsTi, OsY, and OsZr, respectively, suggest that OsM (M=Hf, Ti, Y, and Zr) compounds are weak metals.

Physica Scripta, 2016

A comprehensive study of structure, phase stability, optical and electronic properties of LiAlH4 ... more A comprehensive study of structure, phase stability, optical and electronic properties of LiAlH4 and NaBH4 light-metal hydrides is presented. The calculations are carried out within density functional theory using the full potential linear augmented plane wave method. The exchange-correlation potential is treated within the local density approximation and the generalized gradient approximation (GGA) to calculate the total energy. Furthermore, the Engel–Vosko GGA approach is employed to compute electronic and optical properties such as reflectivity spectra. The phases α, β and γ of LiAlH4 and NaBH4 hydrides are investigated, the phase transition from the β to the high-pressure γ phase is determined for NaBH4 and is accompanied by a 1% volume decrease. For LiAlH4, no phase transition is detected. The materials under consideration are classified as wide band gap compounds. From the analysis of the structures at different phases, it is deduced that the hydrides show strong covalent interaction between B (Al) and H in the [BH4]− ([AlH4]−) anions and ionic bonding character between [BH4]− and Na+ for NaBH4, and [AlH4]− and Li+ for LiAlH4. The complex dielectric function, absorption coefficient and the reflectivity spectra are also computed and analyzed in different phases.

Journal of New Technology and Materials, 2014

A theoretical study of structural, and electronic properties of NaZnAs compound is presented by p... more A theoretical study of structural, and electronic properties of NaZnAs compound is presented by performing ab initio calculations based on density-functional theory using the full-potential linear augmented plane wave (FP-LAPW). The generalized-gradient approximation (GGA) and the local density approximation LDA) are chosen for the exchange-correlation energy. The Engel-Vosko (EVGGA) formalism is applied for electronic properties The calculated structural parameters, such as the lattice constant, bulk modulus and pressure derivative, the electronic band structures and the related total density of states and charge density are presented. The high-pressure α phase of the NaZnAs is investigated and phase transition pressure from tetragonal to high-pressure phase is determined. We have found that the Nowotny-Juza compounds NaZnAs is direct gap semiconductor at ambient pressure. The bonding character and the phase stability of NaZnAs compound are discussed. The nature and the size of the band gap of NaZnAs compound are associated with the bonding character of two Kinds of bonds, namely, Na-As and Zn-As bonds.

International Journal of Modern Physics B, 2004

Based on a pseudopotential scheme, the composition dependence of energy band-gaps of zinc-blende ... more Based on a pseudopotential scheme, the composition dependence of energy band-gaps of zinc-blende Mg x Zn 1-x Se ternary alloys in the composition range of 0≤x≤1 are determined. The effect of deviation of lattice constants of the alloys of interest from Vegard's law on the optical bowing parameter and system transition between the direct and indirect structures is discussed.

Renewable Energy, 2012

For energy band calculations, the indirect energy gap (G _ X) is calculated using density functio... more For energy band calculations, the indirect energy gap (G _ X) is calculated using density functional theory (DFT) of the full potential-linearized augmented plane wave (FP-LAPW) method as implemented in WIEN2K code. The EngeleVosko generalized gradient approximation (EV-GGA) formalism is used to optimize the corresponding potential for energetic transition and optical properties calculations of CdS and CdTe as a function of quantum dot diameter and is used to test the validity of our model of quantum dot potential. The results are compared with others and showed reasonable agreement.

physica status solidi (b), 2011

Physica B: Condensed Matter, 2009

The structural and electronic properties of X 3 As 4 (X ¼ C, Si, Ge and Sn) compounds were invest... more The structural and electronic properties of X 3 As 4 (X ¼ C, Si, Ge and Sn) compounds were investigated using density functional theory (DFT) calculations. We employed both the generalized-gradient approximation (GGA), which is based on exchange-correlation energy optimization to calculate the total energy and the Engel-Vosko (EV-GGA) formalism, which optimizes the corresponding potential for band structure calculations. The calculated lattice constant, bulk modulus and electronic band structure of pseudocubic X 3 As 4 (X ¼ C, Si, Ge and Sn) compounds are in good agreement with other theoretical results. The analysis shows that the hardest material is C 3 As 4 compound with a bulk modulus B 0 ¼ 106.5 GPa, while Si 3 As 4 , Ge 3 As 4 and Sn 3 As 4 have almost the same bulk modulus ranging from 51 to 68.5 GPa. Also we have presented the results of cohesive energies and we have given a detail discussion of the bond lengths and bond angles in the pseudocubic phase of group IV arsenides. Furthermore, band structure and density of states calculations show that Si 3 As 4 , Ge 3 As 4 and Sn 3 As 4 exhibit a semiconductor behavior with indirect gaps while C 3 As 4 exhibit a metallic behavior using both GGA and EV-GGA.

Materials Chemistry and Physics, 2004

Based on the pseudopotential scheme, the electronic properties of zinc-blende Zn 1−x Mg x Se allo... more Based on the pseudopotential scheme, the electronic properties of zinc-blende Zn 1−x Mg x Se alloys have been predicted. The agreement between our calculated electronic band parameters and the available experimental data is generally reasonable. These parameters are found to depend non-linearly on alloy composition x. The electron valence and conduction charge densities derived from pseudopotential calculations for certain concentrations are also reported.

Journal of Solid State Chemistry, 2010

In this research, the structural, electronic, optical and transport properties of SbNSr 3 compoun... more In this research, the structural, electronic, optical and transport properties of SbNSr 3 compound are predicted using the pseudopotential plane wave (PP-PW) method within density functional theory (DFT). Hybrid functionals and traditional approximations in DFT for exchange-correlation potential were used and compared together. To reparametrize Heyd-Scuseria-Ernzerh of (HSE) functional, we predicted the band gap value of SbNSr 3 compound 1.17 eV that is in the better agreement with experiment than other theoretical results. The modified HSE functional calculated the lattice parameter with an acceptable accuracy in compared to experimental lattice constant. The optical properties such as the real and imaginary part of dielectric function and the electron energy loss were calculated by the modified HSE functional. Consideration of the transport properties like the electronic thermal and electrical conductivity, Seebeck coefficient as well as thermoelectric figure of merit show that this material can be considered as a good thermoelectric material in low temperatures.

Journal of Physics: Condensed Matter, 2005

The structural properties of the (Zn, Mg) (S, Se) solid solutions are determined by a combination... more The structural properties of the (Zn, Mg) (S, Se) solid solutions are determined by a combination of the computational alchemy and the cluster expansion methods with Monte Carlo simulations. We determine the phase diagram of the alloy and show that the homogeneous phase is characterized by a large amount of short-range order occurring among first-nearest neighbors. Electronic-structure calculations performed using the special quasirandom structure approach indicate that the energy gap of the alloy is rather sensitive to this short-range order. [S0031-9007(98)06238-3]

Journal of Materials Science, 2014

ABSTRACT First-principle calculations have been carried out on the structural, electronic, elasti... more ABSTRACT First-principle calculations have been carried out on the structural, electronic, elastic, and phonon properties of the full-Heusler alloys X2YAl (X = Co, Fe and Y = Cr, Sc). The calculations predict that the Fe2CrAl and Co2CrAl are half-metallic ferromagnets at the equilibrium lattice constant with a minority-spin energy gap of 0.2912 and 0.668 eV, respectively. Fe2ScAl exhibit a gap in the majority density of states, with a few states at the Fermi level and about 0.217 states eV−1, unlike the other Heusler compounds; due to this, it is considered a false half metal, and Co2ScAl is considered a non-magnetic compound. The elastic constants were derived from the slopes of the acoustic branches in the phonon-dispersion curve. The calculated lattice constants, bulk modulus, and first-order pressure derivative of the bulk modulus are reported for the L21 structure and compared with previous values. Phonon-dispersion curves were obtained using the first-principle linear-response approach of the density-functional perturbation theory. The specific heat capacity at a constant volume C V of X2YAl (X = Co, Fe and Y = Cr, Sc) alloys is calculated and discussed.