Browsing by Author "Hamad, B."

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Ab Initio Investigations of the Structural, Electronic, Magnetic and Mechanical Properties of Crx (X = As, Sb, Se, and Te) Transition Metal Pnictides and Chalcogenides
(Iop Publishing Ltd, 2019) Charifi, Z.; Guendouz, D. J.; Baaziz, H.; Soyalp, F.; Hamad, B.
The structural, electronic, magnetic, and mechanical properties of CrX (X = As, Sb, Se and Te) transition metal pnictides and chalcogenides were investigated using ab initio density functional theory using the local density approximation and generalized gradient approximation. Under ambient conditions, CrAs and CrTe are stable in the orthorhombic MnP (MP)-type antiferromagnetic (AFM) and hexagonal NiAs (NA) (FM) structures, respectively, whereas CrSb and CrSe have NA-type (AFM) structure. The half-metallic behavior was predicted for the zinc blende (ZB) and wurtzite (WZ) structures of CrAs, the zinc blende (ZB)-type of CrSb and CrSe compounds and the zinc blende (ZB) and rock salt (RS) structures of CrTe. However, the remaining structures are found to exhibit a metallic behavior. The highest total magnetic moment of 4 mu(B) was predicted for the RS and ZB (FM) structures of CrTe. The investigated CrX compounds were found to be mechanically stable at ambient pressure. The high value of B/G ratio indicates that CrSb (NA) is a ductile material, whereas CrAs (MP), CrSe and CrTe (NA) are brittle due to the lower B/G value.
A Dft Study of the Electronic and Magnetic Properties of Fe2mnsi1-Xgex Alloys
(Elsevier, 2012) Hamad, B.; Charifi, Z.; Baaziz, H.; Soyalp, F.
We performed density functional theory (DFT) calculations to study the structural, electronic and magnetic properties of Fe2MnSi1-xGex alloys (x=0, 0.25, 0.50, 0.75, and 1.00). The lattice constant is found to increase linearly as a function of Ge concentration with a decrease in the formation energy. The total magnetic moment is found to be 3 mu(B) for all alloys with the most contribution from Mn local magnetic moments. Iron atoms, however, exhibit much smaller spin moments about 10% of the bulk value. It seems that due to the proximity of Fe, magnetic moments have been induced on the sp atoms, which couple antiferromagnetically with Fe and Mn spin moments. Although, the band gap remains almost constant (0.5 eV), the spin-flip gap decreases as a function of x. (C) 2012 Elsevier B.V. All rights reserved.
Theoretical Investigations of Co2mn1-Xcrxsn and Co2mnsn1-Ysiy Pseudo-Ternary Alloys: First Principles Calculations
(Elsevier Science Bv, 2015) Charifi, Z.; Hamad, B.; Baaziz, H.; Soyalp, F.
The electronic and magnetic properties of Co2Mn1-xCrxSn and Co2MnSn1-ySiy alloys are investigated using density functional theory (OFT) within a full-potential linearized augmented-plane-wave (FPLAPW) method. Amongst the systems under investigation, Co2MnSn1-ySiy alloys show half metallicity with 100% spin polarization at the Fermi level, however Co2Mn1-xCrxSn are found to be pseudo-half metals with Few minority states at the Fermi level and high spin polarization. The substitution of Si with Sn keeps the magnetic moment constant in Co2MnSn1-ySiy alloys, whereas the substitution of Mn with Cr decreases the magnetic moment and degrade the half-metallicity in Co2Mn1-xCrxSn alloys. The Curie temperature is calculated and it is found to be about 928 K for all Co2MnSn1-ySiy alloys, whereas it decreases linearly with x for Co2Mn1-xCrxSn alloys. The lattices constants, bulk modulii, energy gaps, polarization ratio and density of states are calculated and their variation versus x or y are discussed. (C) 2015 Elsevier B.V. All rights reserved.