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First-Principles Study of the Structural, Electronic, Magnetic and Thermal Properties of the Cr Doped Ge₆Mn₂Te₈ and Ge₆Fe₂Te₈ Systems

100%

Semari F., Baki N., Khachai H., Yakoubi A., Méçabih S., Khenata R., Shankar A., Rai D., Bouhemadou A.

Acta Physica Polonica A

2017

vol. 132

issue 4

1242-1250

First-principles calculations have been used to study the structural, electronic, magnetic, and thermal properties of the Cr doped Ge₆Mn₂Te₈ and Ge₆Fe₂Te₈ systems. The calculations were performed using the full-potential linearized augmented plane wave plus local orbitals (FP-LAPW + LO) method based on the spin-polarized density functional theory. Additionally, the electronic exchange-correlation potential is approximated using the spin generalized gradient approximation. The structural properties of the Ge₅Mn₂CrTe₈ and Ge₅Fe₂CrTe₈ alloys are indicated by their corresponding lattice constants, values of the bulk moduli and their pressure derivatives. An analysis of the band structures and the densities of states indicate that for both alloys, they present nearly half-metallic ferromagnetism character. The band structure calculations are used to estimate the spin-polarized splitting energies, Δp_{x}(d) and Δp_{x}(pd) produced by the 3d Mn, 3d Fe and 3d Cr doped states as well as the s(p)-d exchange constants, N₀α (conduction band) and N₀β (valence band). It is observed that the p-d hybridization reduces the magnetic moment of the Mn and Fe atoms from their atomic charge values and create small local magnetic moments on the nonmagnetic Ge and Te sites. Furthermore, the calculations of the charge density indicate that both compounds have ionic bonding character. Through the quasi-harmonic Debye model, the effects of pressure P and temperature T on the bulk modulus B, the primitive cell volume V/V₀, the Debye temperature θ_{D}, the Grüneisen parameter γ, the heat capacity C_{V}, the entropy S, as well as the thermal expansion coefficient, α of the Ge₆Mn₂Te₈, Ge₅Mn₂CrTe₈, Ge₆Fe₂Te₈ and Ge₅Fe₂CrTe₈ alloys are predicted.

Ab Initio Study of the Mechanical, Thermal and Optoelectronic Properties of the Cubic CsBaF₃

100%

Harmel M., Khachai H., Haddou A., Khenata R., Murtaza G., Abbar B., Bin Omran S., Khalfa M.

Acta Physica Polonica A

2015

vol. 128

issue 1

34-42

We have investigated the structural, elastic, electronic, optical and thermal properties of CsBaF₃ perovskite using the full-potential linearized augmented plane wave method within the generalized gradient approximation and the local density approximation. Moreover, the modified Becke-Johnson potential (TB-mBJ) was also applied to improve the electronic band structure calculations. The ground state properties such as lattice parameter, bulk modulus and its pressure derivative were calculated and the results are compared with the available theoretical data. The elastic properties such as elastic constants, anisotropy factor, shear modulus, Young's modulus and Poisson's ratio are obtained for the first time. Electronic and bonding properties are discussed from the calculations of band structure, density of states and electron charge density. The contribution of the different bands was analyzed from the total and partial density of states curves. The different interband transitions have been determined from the imaginary part of the dielectric function. The thermal effect on the volume, bulk modulus, heat capacities C_V and the Debye temperature was predicted using the quasi-harmonic Debye model, in which the lattice vibrations are taken into account.

Structural, Chemical Bonding, Electronic and Magnetic Properties of XY_{3} (X = Al, Ga and Y = V, Nb, Cr, Mo) Compounds

100%

Hafeez R., Murtaza G., Khenata R., Wong K., Naeem S., Khalid M., Alahmed Z., Bin Omran S.

Acta Physica Polonica A

2015

vol. 127

issue 3

770-779

The metallic behavior of the band gap of intermetallic compounds has large applications in superconductivity, nickel-metal hydrides batteries, semiconductors, and heating materials. The presence of transition elements makes them more attractive for magnetic applications. In this work we studied the structural, electronic, chemical bonding, and magnetic properties of binary intermetallic compounds XY_3 (X = Al, Ga and Y = V, Nb, Cr, Mo). These compounds were investigated by using full potential linearized augmented plane wave plus local orbitals method. The exchange correlation potential of generalized gradient is used. Our calculated lattice constants are in good agreement with experimental values. The band structures of these compounds are purely overlapping across the Fermi level. The bonding is mainly covalent in these compounds. The density of states of the compounds shows that the major contribution arises from d-states of anions. The investigation carried out shows that the most of these compounds have ferromagnetic nature, while few are diamagnetic. On the basis of this study it is expected that these compounds can be used as a best moulds for future study on similar compounds.

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3 Acta Physica Polonica A

1 2017

2 2015

3 Khenata R.

2 Bin Omran S.

2 Khachai H.

2 Murtaza G.

1 Abbar B.

1 Alahmed Z.

1 Baki N.

1 Bouhemadou A.

1 Haddou A.

1 Hafeez R.

1 Harmel M.

1 Khalfa M.

1 Khalid M.

1 Méçabih S.

1 Naeem S.

1 Rai D.

1 Semari F.

1 Shankar A.

1 Wong K.

1 Yakoubi A.

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First-Principles Study of the Structural, Electronic, Magnetic and Thermal Properties of the Cr Doped Ge₆Mn₂Te₈ and Ge₆Fe₂Te₈ Systems

Ab Initio Study of the Mechanical, Thermal and Optoelectronic Properties of the Cubic CsBaF₃

Structural, Chemical Bonding, Electronic and Magnetic Properties of XY_{3} (X = Al, Ga and Y = V, Nb, Cr, Mo) Compounds