arXiv subjects

M. Abou Ghantous

Publications and source records attributed to M. Abou Ghantous.

2 recordsLinked to original sources

arXiv2023

Sublattice magnetizations of ultrathin ferrimagnetic lamellar nanostructures between cobalt leads

In this work we model the salient magnetic properties of the alloy lamellar ferrimagnetic nanostructures $[Co_{1-c}Gd_c]_{\ell^{\prime}}[Co]_\ell[Co_{1-c}Gd_c]_{\ell^{\prime}}$ between $Co$ semi-infinite leads. We have employed the Ising spin effective field theory (EFT) to compute the reliable magnetic exchange constants for the pure cobalt $J_{Co-Co}$ and gadolinium $J_{Gd-Gd}$ materials, in complete agreement with their experimental data. The sublattice magnetizations of the $Co$ and $Gd$ sites on the individual hcp atomic (0001) planes of the $Co-Gd$ layered nanostructures are computed for each plane and corresponding sites, by using the combined EFT and mean field theory (MFT) spin methods. The sublattice magnetizations, effective site magnetic moments, and ferrimagnetic compensation characteristics for the individual hcp atomic planes of the embedded nanostructures, are computed as a function of temperature, and for various stable eutectic concentrations in the range $c\leq$ 0.5. The theoretical results for the sublattice magnetizations and the local magnetic variables of these ultrathin ferrimagnetic lamellar nanostructured systems, between cobalt leads, are necessary for the study of their magnonic transport properties, and eventually their spintronic dynamic computations. The method developed in this work is general and can be applied to comparable magnetic systems nanostructured with other materials.

cond-mat.mes-hall↗

arXiv2015

Quantum conductance of silicon-doped carbon wire nanojunctions

The unknown quantum electronic conductance across nanojunctions made of silicon-doped carbon wires between carbon leads is investigated. This is done by an appropriate generalization of the phase field matching theory for the multi-scattering processes of the electronic excitations at the nanojunction, and the use of the tight-binding method. Our calculations of the electronic band structures for carbon, silicon and diatomic silicon carbide, are matched with the available corresponding density functional theory results to optimize the required tight-binding parameters. The silicon and carbon atoms are treated on the same footing by characterizing each with their corresponding orbitals. Several types of nanojunctions are analyzed to sample their behavior under different atomic configurations. We calculate for each nanojunction the individual contributions to the quantum conductance for the propagating $σ$, $π$, and $σ^{*}$ electrons incident from the carbon leads. The calculated results show a number of remarkable features, which include the influence of the ordered periodic configurations of silicon-carbon pairs, and the suppression of the quantum conductance due to minimum substitutional disorder and to artificially organized symmetry on these nanojunctions. Our results also demonstrate that the phase field matching theory is an efficient tool to treat the quantum conductance of complex molecular nanojunctions.

cond-mat.mes-hall↗