• F EL HAJ HASSAN

      Articles written in Pramana – Journal of Physics

    • First-principle calculations of structural, electronic, optical, elastic and thermal properties of $\rm{MgXAs_{2} (X = Si, Ge)}$ compounds

      S CHEDDADI K BOUBENDIRA H MERADJI S GHEMID F EL HAJ HASSAN S LAKEL R KHENATA

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      First-principle calculations on the structural, electronic, optical, elastic and thermal properties of the chalcopyrite $\rm{MgXAs_{2} (X = Si, Ge)}$ have been performed within the density functional theory (DFT) using the full potential linearized augmented plane wave (FP-LAPW) method. The obtained equilibrium structural parameters are in good agreement with the available experimental data and theoretical results. The calculated band structures reveal a direct energy band gap for the interested compounds. The predicted band gaps using the modified Becke–Johnson(mBJ) exchange approximation are in fairly good agreement with the experimental data. The optical constants such as the dielectric function, refractive index, and the extinction coefficient are calculated and analysed. The independent elastic parameters namely, $C_{11}, C_{12}, C_{13}, C_{33}, C_{44}$ and $C_{66}$ are evaluated. The effects of temperature and pressure on some macroscopic properties of $\rm{MgSiAs_{2}}$ and $\rm{MgGeAs_{2}}$ are predicted using the quasiharmonic Debye model in which the lattice vibrations are taken into account.

    • Ab initio study of the fundamental properties of $\rm{Zn_{1−x}TM_{x}Se (TM=Mn, Co \, and \, Fe)}$

      F SOLTANI H BAAZIZ Z CHARIFI F EL HAJ HASSAN B HAMAD

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      The structural, electronic, magnetic, thermal and elastic properties of $\rm{Zn_{1−x}TM_{x}Se (TM=Mn, Co \, and \, Fe)}$ ternary alloys are investigated at $x$ = 0, 0.25, 0.50, 0.75 and 1.00 in the zincblende (B3) phase. The calculations are performed using all-electron full-potential linearised augmented plane-wave (FP-LAPW) method within the framework of the density functional theory (DFT) and the generalised gradient approximation (GGA). The electronic and magnetic properties were performed using the modified Becke–Johnson potential combined with the GGA correlation (mBJ-GGA). The electronic structures are found to exhibit a semiconducting behaviour for $\rm{Zn_{1−x}Mn_{x}Se}$ and $\rm{Zn_{1−x}Co_{x}Se}$ and a half-metallic behaviour for $\rm{Zn_{1−x}Fe_{x}Se}$ alloys at all concentrations, while CoSe with $x = 1.00$ is found to exhibit a metallic behaviour. The calculated magnetic moment per substituted transition metal (TM) Mn, Co and Fe atoms for half-metallic compounds are found to be 2.5, 1.5 and 2 $\mu_{B}$, respectively. The p–d hybridisation between the TM d- and Se p-states reduces the local magnetic moment of Mn, Co and Fe and induces small local magnetic moments on Zn and Se sites. In addition, we discuss the mechanical behaviour of binary and ternary compounds and all compounds studied here are mechanically stable.

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