Ahmed Boufelfel

University of Guelma · Physics

The structural, magnetic, and magneto-optical properties of the PdM (M=Fe, Co, Ni) alloy are investigated using first-principles calculations with the exciting code. The study employs the full potential linearized augmented plane wave method (FP-LAPW) based on density functional theory (DFT). The exchange-correlation energy is described in the gene...

I provide a new helpful bottom up approach for guidance in the search for adequate cathode material in general and specifically lithium ion batteries (LIB) in this paper. Namely, ab initio calculations of second order elastic constants and phonons dispersion spectra were used. I calculated the elastic properties, phonons dispersion and heat capacit...

A new helpful bottom up approach for guidance in the search for adequate cathode material in general and specifically lithium ion batteries (LIB). The method is based on ab initio calculations of second order elastic constants and phonons dispersion spectra.

The effect of H position in L10FePd magnetic equiatomic layered structure on electron-phonon interactions is studied via ab initio pseudopotentials density functional approach in the general gradient approximation. The structures investigated are L10FePd (parent structure), and the specific hydrides 2(FePd)1H (H@Fe layer) and 2(FePd)2H (H@Pd layer)...

Using quantum chemistry, we modeled the docking process of flavanone Naringenin guest molecule (Narg) in the host β-Cyclodextrin (β-CD) and also in modified heptakis(2,6-di-O-methyl)-β-CD (DIMEB). The effect of host methylation on the complexation behavior was highlighted through structural, electronic and nuclear studies. All ONIOM2 combinations o...

Dynamics and thermodynamics properties of mono equi-atomic multilayer of Fe/Pd L10 tetragonal structure where H is placed in Fe or Pd or both layers with formula 2(FePd)nH (n=0,1,2,3) are reported. These findings are computed using a combination of density-functional theory total-energy calculations and density-functional perturbation theory lattic...

Iron-Palladium (FePd) alloys and multilayers have been subjected to an extensive amount of research on their magnetic properties, in the hope of use in high density magnetic recording media and spintronics applications [1]. Besides, FePd appears to be one of the most promising ferromagnetic shape memory alloys attractive for such practical multifun...

We investigated, using first principle calculations, the inclusion process of anticoagulant Warfarin (Warf) in two cavitand supramolecules: β-cyclodextrin (β-CD) and p-tert-butylcalix[4]arene (Calix). We considered all plausible cases of inclusion which differ by the moiety of Warf pointing to Head (H) or Tail (T) part of β-CD or to upper rim of Ca...

We have studied the magnetism in the hexagonal polymorph of BaTiO3 doped with one of the transition metals (TM = Co, Fe, Cr) and in the presence of oxygen vacancies. The formation energies for BaTi0.95TM0.05O3−δ ; (TM = Co, Fe, Cr) are 8.10, 8.80, and 12.36 eV, respectively. The antiferromagnetic (AFM) phase of BaTiO3 has changed to a ferromagnetic...

Using ab initio calculations, I fully describe the electronic, magnetic and elastic properties of mono equi-atomic multilayer of L10 FePd and FePdH where H belongs to one of the two layers or to both. I found that the magnetic polarization of palladium in FePd is almost annihilated when hydrogen is present in both atomic layers. On the other hand t...

Abstract: In this talk I will revisit the Schrodinger equation and cite the impact on twenty first century physical sciences. This differential equation paved the way to nano science and nano technology which are flourishing nowadays. This success is the result from a huge boost from the recent advances in computation hardware technology and softwa...

We investigated the inclusion ofWogonin in β-cyclodextrin using several quantum mechanical models. Among the two considered modes of complexation, both PM3 and ONIOM2 results proved that the lowest energy structure is obtained from ‘A’ orientation. The most stable geometry presents a partial inclusion of Wogonin with the aromatic ring totally embed...

We have prepared solid thin film samples of SnO2:Sb in different ratios using atmospheric pressure chemical vapour deposition technique APCVD. The chemical composition was determined with Rutherford Backscattering Spectroscopy (RBS) within an error of 1%. X-ray diffraction was used to study the influence of Sb concentration on the lattice parameter...

We calculated, using spin polarized density functional theory, the electronic properties of zigzag (10,0) and armchair (6,6) semiconductor silicon carbide nanotubes (SiCNTs) doped once at the time with boron, nitrogen, and oxygen. We have looked at the two possible scenarios where the guest atom X (B, N, O), replaces the silicon XSi, or the carbon...

Inclusion complex MM+, Amber 99 Monte Carlo simulation We simulated the docking of the fullerene C 60 in β-Cyclodextrin using two models. We considered in this study complexes formed by 1:1 and 1:2 guest–host stoichiometries in vacuum and aqueous phase. We investigated three orientations for β-CDs in 1:2 complexes, Head to Head (HH), Head to Tail (...

We investigated the inclusion process of Lamotrigine (LMN) in beta cyclodextrin (β-CD) with 1:1 stoichiometry using empirical, semi-empirical and quantum mechanical calculations models. We have found that the quantum and hybrid ONIOM2 methods gave the most favorable orientation in which the guest molecule is totally sequestered in the hydrophobic c...

We have used a fully controlled APCVD experimental set up to prepare solid thin film samples of SnO2:Sb in different ratios. We used non destructive techniques to characterize our samples. X-ray diffraction was used to study the influence of Sb concentration on the lattice parameters and phase orientations. We have found that sample of concentratio...

We have performed self-consistent calculations to study the interlayer exchange coupling and transport properties of FM/Os/FM trilayers (FM = Co, Fe, FeCo and FePt) as a function of the osmium spacer thickness. Our results are in a good agreement with the published experimental results. The antiferromagnetic (AF) coupling observed experimentally in...

A cosine-squared flux distribution from a disk-shaped source was used to calculate the spatial deposition profiles for films sputtered onto rotating substrates. Depositions were made by a stable and reproducible d.c. sputtering machine and thicknesses measured by Rutherford backscattering spectroscopy to compare with this calculation. The measured...

A series of Fe/Pd superlattices of varying numbers of atoms per layer were fabricated. Structural properties were characterized by x-ray diffraction. Magnetic properties were studied by Moessbauer spectroscopy and transport properties by electrical-conductivity measurements. All properties studied could be explained by structural characteristics, s...

A series of Fe/Pd superlattices of varying numbers of atoms per layer were fabricated. Structural properties were characterized by x-ray diffraction. Magnetic properties were studied by Mossbauer spectroscopy and transport properties by electrical-conductivity measurements. All properties studied could be explained by structural characteristics, su...

We report the structural and magnetic properties of a new class of Fe/Pd second-order superlattices, formed by alternating two bilayers with different repeat periods. Chemical and structural characterization were obtained using Rutherford backscattering spectroscopy (RBS) and several x-ray diffraction techniques, respectively. The properties of the...

We have made Fe/Pd superlattices with periodic modulation wavelength Λ ranging from 33.2 to 188.4 Å. Long‐range structural coherency is inferred from several x‐ray diffraction techniques. Fe and Pd were found to grow (110) and (111) parallel to the substrate, respectively. The in‐plane electrical resistivity was measured in the range 7.5–300 K by t...

We report on the observation and the analysis of collective magnetostatic spin‐wave excitations in magnetic superlattices. The influence of interface anisotropies, which can become dominant for small modulation wavelengths, is discussed. For the system Fe/Pd we show that Brillouin spectroscopy experiments in combination with the measurement of the...

We have sputter deposited Fe/W superlattices on several types of substrates using magnetically enhanced dc sputtering guns. The deposition rates were controlled to better than 0.3%. We used a 6‐MV Rutherford backscattering facility to determine the chemical composition with 0.5% relative uncertainty. We varied the modulation wavelength from Λ=4.4 t...

For the first time we prepared and investigated the structural, magnetic, and electrical transport properties of Fe/W, Fe/Mo, and Fe/Pd metallic superlattices. We made a theoretical attempt to explain the induced increase or decrease of the magnetization at the magnetic superlattice interfaces. We used several x-ray diffraction techniques to determ...

In Fe/Pd and Fe/W multilayers the complete, theoretically predicted band of collective magnetostatic spin‐wave excitations has been observed. Despite the large number of bilayers (49–90) discrete spin‐wave modes have been found in the upper half of the band. For Fe/Pd multilayers the saturation magnetization shows a monotonic reduction of up to 30%...

The complete, theoretically predicted band of collective magneto- static spin-wave excitations has been observed for the first time in Fe-Pd and Fe-W multilayer structures by Brillouin scattering. Despite the large number of bilayers (49-90) discrete spin-wave modes due to a quantization of the momentum perpendicular to the stack have been observed...

The Rayleigh mode and up to six higher-order localized acoustic (Sezawa) surface modes have been observed in Fe-Pd multilayer structures using Brillouin scattering. The effective elastic constants of the multilayer structures have been determined from a fit of the measured mode dispersions. With decreasing multilayer modulation wavelength from 87 t...

A method is presented which uses a cosine-squared flux distribution from a disk-shaped source to calculate the spatial deposition profiles for films sputtered onto rotating substrates. To compare to this calculation depositions were made by dc sputtering and thicknesses measured by three independent techniques. The measured and calculated profiles...

An introduction to metal-metal superlattices is presented, along with a brief review of some of the materials which have been made, and phenomena which have been observed, so far. We describe in detail the results of a number of structural characterization techniques applied to these materials, including Bragg theta-2theta x-ray diffraction, transm...

The Rayleigh mode and up to six higher order localized acoustic (Sezawa) surface modes have been observed in Fe/Pd multilayers by Brillouin scattering. The effective elastic constants of the multilayers have been determined from a fit of the measured mode dispersions. With decreasing modulation wavelength of the multilayers from 87 A to 33 A the el...

Thesis (M.S. - Physics)--University of Arizona, 1987. Includes bibliographical references (leaves 67-71). Microfiche. s