Browsing by Author "Rached, D."

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Half-Metallic Ferromagnetism in Al1-Xcrxp and Superlattices (alp)n/(crp)m by Density Functional Calculations
(Academic Press Ltd- Elsevier Science Ltd, 2014) Merabet, M.; Rached, D.; Benalia, S.; Reshak, A. H.; Bettahar, N.; Righi, H.; Labair, M.
Using the first-principles full-potential linear muffin-tin orbital (FP-LMTO) method based on density functional theory, we have investigated the electronic structure and magnetism of order dilute ferromagnetic semiconductor Al1-xCrxP (x = 0.125, 0.25 and 0.50) and the superlattices (AlP)(1)/(CrP)(1) and (AlP)(3)/(CrP)(1). For the exchange-correlation functional, the generalized gradient approximation (GGA) has been used. It is shown that these compounds are half-metallic ferromagnets. Calculations of the s-d exchange constant N-0 alpha and p-d exchange constant N-0 beta clearly indicate the magnetic nature of these compounds. We observe that p-d hybridization reduces the local magnetic moment of Cr from its free space charge value and produces small local magnetic moments on the non-magnetic Al and P sites. (C) 2013 Elsevier Ltd. All rights reserved.
Prediction Study of the Mechanical and Thermodynamic Properties of the (R Sm, Eu, Gd, and Tb) Compounds
(Springer/plenum Publishers, 2013) Mekkaoui, F.; Litimein, F.; Khenata, R.; Merabiha, O.; Bouhemadou, A.; Varshney, D.; Rached, D.
The structural, elastic, and thermodynamic properties of the cubic anti-perovskite (R = Sm, Eu, Gd, and Tb) compounds have been investigated using first principles full-potential augmented-plane wave plus local orbitals (FP-APW+lo) method with the generalized gradient approximation. The ground-state quantities such as the lattice parameter, bulk modulus, and its pressure derivative, as well as elastic constants are estimated. Computed equilibrium lattice constants agree well with the available experimental data. The full set of first-order elastic constants and their pressure dependence, which have not been calculated or measured yet, have been determined. The elastic moduli increase linearly with increasing pressure and satisfy the generalized elastic stability criteria for cubic crystals under hydrostatic pressure. The shear modulus, Young's modulus, and Poisson's ratio are calculated for ideal polycrystalline aggregates. The Debye temperature is estimated from the average sound velocity. From the elastic parameter behavior, it is inferred that cubic anti-perovskites are ductile in nature and that the bonding is predominantly of an ionic nature. Following the quasi-harmonic Debye model, the temperature effect on the lattice constant, bulk modulus, heat capacity, and Debye temperature is calculated reflecting the anharmonic phonon effects.