arXiv subjects

Taoufik Sakhraoui

Publications and source records attributed to Taoufik Sakhraoui.

3 recordsLinked to original sources

arXiv2026

DFTB coupled with NEGF study of the structural, electronic and transport properties of goldene 2D material

We report the structural, electronic, and transport properties of the goldene 2D material using the density functional tight-binding (DFTB) method. Electronic transport calculations were conducted in conjunction with the non-equilibrium Green's functions (NEGF) technique. Our study reveals that the Au 2D material is dynamically and thermally stable, and it possesses good elastic properties. On the other hand, goldene has a linear relationship between current and voltage at low potentials, indicating its metallic character. The calculated current-potential curve correlates well with transmission functions and the electronic density of states around the Fermi level. We also investigated the electronic structure and magnetic properties of silicon (Si)-doped Au 2D material. Our results show that the Si atom can induce a local magnetic state in the goldene monolayer. The resulting magnetic moment is 0.63 $μ_B$.

cond-mat.mtrl-sci↗

arXiv2025

Unveiling the magnetic behavior of C$_{\rm3}$N$_{\rm4}$ 2D material by defect creation, defect passivation, and transition metal adsorption

Using the density functional tight binding method (DFTB) and the GFN1-xTB (Geometries, Frequencies, and Noncovalent interactions Tight Binding) Hamiltonian, we have investigated the structural, electronic and magnetic properties of vacancy defects, hydrogen and oxygen passivated defects, and Fe adsorption in two-dimensional (2D) graphitic carbon nitride (gt-C$_3$N$_4$) 2D material. The ring shape is the most preferred vacancy evolution path, with significant stability of the semicircle fourfold C-N-C-N vacancy. We found that bare gt-C$_3$N$_4$ which is non-magnetic becomes magnetic by 2-, and 5-defects creation, hydrogen/oxygen passivation of the defects, and upon Fe adsorption. Interestingly, Fe atoms interact with the gt-C$_3$N$_4$ sheet and result in a ground ferromagnetic (FM) state. In addition, we investigate the effects of passivating the vacancies by hydrogen in gt-C$_3$N$_4$ on its structural, electrical, and magnetic properties. We found that substituting the 1, 2, and 3 vacancies with hydrogen and passivating the 6-defect with oxygen turns on magnetism in the system. Due to structural distortion, the passivated defects do not have a well-ordered magnetic orientation. However, passivating the remaining defected structures maintains the nonmagnetic state. It is also shown that passivation leads to a semiconductor with a band gap value higher than that of the bare material. We also calculate the electronic and magnetic properties of transition metal (TM) atoms, including V, Cr, Mn, Fe, Co, Ni-adsorbed gt-C$_3$N$_4$ monolayer. All TM atoms show slight lattice distortion, and the adsorbed system almost maintains the original structure type. Moreover, a FM alignment was observed with a total magnetic moments of 2.89 $μ_B$, 2 $μ_B$, and 1 $μ_B$ for V, Fe, and Co atoms, respectively. The Cr, Mn, and Ni atoms induce no magnetism to the non magnetic gt-C$_3$N$_4$ system.

cond-mat.mtrl-sci↗

arXiv2024

Prediction of induced magnetism in 2D Ti$_2$C based MXene by manipulating the mixed surface functionalization and metal substitution computed by xTB model Hamiltonian of the DFTB method

We employed the recently developed density functional tight binding (DFTB) method's Hamiltonian, GFN1-xTB, for modeling the mixed termination in Ti$_{\rm2}$C MXene, namely three types of termination by combining -O and -OH, -O and -F, as well as -F and -OH. We demonstrated that the approach yields reliable predictions for electronic and magnetic properties of such MXenes. The first highlighted result is that the mixed surface functionalization in Ti$_{\rm2}$CA$_{\rm x}$B$_{\rm y}$ MXene induces spin polarization with diverse magnetic alignments, including ferromagnetism and two types of antiferromagnetism. We further identified the magnetic alignment for the investigated MXene in terms of the compositions of the terminal groups. Moreover, the effect of the transition metal (Ti) substituted by the Sc atom on the electronic and magnetic properties were also investigated. We found that the studied systems maintain the magnetism and the metallic characteristics. A magnetic transition from antiferromagnetic (AFM) to ferrimagnetic (FiM) ordering was found for ScTi$_{\rm15}$C$_{\rm8}$F$_{\rm8}$(OH)$_{\rm8}$ and ScTi$_{\rm15}$C$_{\rm8}$F$_{\rm12}$(OH)$_{\rm4}$ compounds. Finally, we proved that incorporating the Sc atom into the lattice of Ti$_{\rm2}$CO$_{\rm2}$ and mixed surface termination Ti$_{\rm2}$CA$_{\rm x}$B$_{\rm y}$ is an effective strategy to induce magnetism. Our study may provide a new potential application for designing MXene-based spintronics.

cond-mat.mtrl-sci↗