arXiv subjects

Jaouad El-hassouny

Publications and source records attributed to Jaouad El-hassouny.

4 recordsLinked to original sources

arXiv2024

Tunneling in ABC trilayer graphene superlattice

We study the transport properties of Dirac fermions in ABC trilayer graphene (ABC-TLG) superlattices. More specifically, we analyze the impact of varying the physical parameters -- the number of cells, barrier/well width, and barrier heights -- on electron tunneling in the ABC-TLG. In the initial stage, we solved the eigenvalue equation to determine the energy spectrum solutions for the ABC-TLG superlattices. Subsequently, we applied boundary conditions to the eigenspinors and employed the transfer matrix method to calculate transmission probabilities and conductance. For the two-band model, we identified the presence of Klein tunneling, with a notable decrease as the number of cells increased. The introduction of interlayer bias opened a gap as the number of cells increased, accompanied by an asymmetry in scattered transmission. Increasing the barrier/well width and the number of cells resulted in an amplified number of gaps and oscillations in both two-band and six-band cases. We observed a corresponding decrease in conductance as the number of cells increased, coinciding with the occurrence of a gap region. Our study demonstrates that manipulating parameters such as the number of cells, the width of the barrier/well, and the barrier heights provides a means of controlling electron tunneling and the occurrence of gaps in ABC-TLG. Specifically, the interplay between interlayer bias and the number of cells is identified as a crucial factor influencing gap formation and transmission asymmetry.

cond-mat.mes-hall↗

arXiv2023

Spin-dependent transmission in curved graphene superlattice

We investigate spin-dependent transmission in a curved graphene superlattice of $N$ cells where each one is made up of four regions. The first is concave, and the third is convex, two arcs of circles separated by a distance $d$ from flat graphene sheets. The tunneling analysis allows us to determine all transmission and reflection channels associated with our system. As a result, we show that the number of cells acts by decreasing the transmissions with the same spin. We predict a solid spin-filtering effect when $d$ and $N$ are sufficiently large. Finally, it is determined that the degree and duration of suppression of the transmissions with the same spin over a range of energy are controllable using $d$.

cond-mat.mes-hall↗

arXiv2022

Tuning Gap in Corrugated Graphene with Spin Dependence

We study transmission in a system consisting of a curved graphene surface as an arc (ripple) of circle connected to two flat graphene sheets on the left and right sides. We introduce a mass term in the curved part and study the effect of a generated band gap in spectrum on transport properties for spin-up/-down. The tunneling analysis allows us to find all transmission and reflections channels modeled by the band gap. This later acts by decreasing the transmissions with spin-up/-down but increasing with spin opposite, which exhibit some behaviors look like bell-shaped curve. We find resonances appearing in reflection with the same spin, thus backscattering with a spin-up/-down is not null in ripple. We observe huge spatial shifts for the total conduction in our model and the magnitudes of these shifts can be efficiently controlled by adjusting the band gap. This high order tunability of the tunneling effect can be used to design highly accurate devises based on graphene.

cond-mat.mes-hall↗

arXiv2022

Tunneling in rippled graphene superlattice with spin dependence and a mass term

The insertion of the band gap $Δ$ in the rippled graphene superlattice leads to new outcomes, as demonstrated. The essential thing is the appearance of opposite-spin transmissions, which increase with $Δ$ and vanish without it. Furthermore, compared to the $Δ=0$ scenario, the duration of the suppression of the transmission with the same spin is longer, with many peaks. The maximum value of transmissions with the same spin declines and remains around unity. Furthermore, for particular energy values, a shift in the behavior of the transmission channels is found. As a result, we demonstrate that with $Δ$, transmission filtering becomes crucial. Finally, as a result of the band gap, distinct variations in total conductance are discovered.

cond-mat.mes-hall↗