arXiv subjects

Zahra Noorinejad

Publications and source records attributed to Zahra Noorinejad.

2 recordsLinked to original sources

arXiv2024

Tilted Dirac Cones in Two-Dimensional Materials: Impact on Electron Transmission and Pseudospin Dynamics

This study is devoted to the profound implications of tilted Dirac cones on the quantum transport properties of two-dimensional (2D) Dirac materials. These materials, characterized by their linear conic energy dispersions in the vicinity of Dirac points, exhibit unique electronic behaviors, including the emulation of massless Dirac fermions and the manifestation of relativistic phenomena such as Klein tunneling. Expanding beyond the well-studied case of graphene, the manuscript focuses on materials with tilted Dirac cones, where the anisotropic and tilted nature of the cones introduces additional complexity and richness to their electronic properties. The investigation begins by considering a heterojunction of 2D Dirac materials, where electrons undergo quantum tunneling between regions with upright and tilted Dirac cones. The role of tilt in characterizing the transmission of electrons across these interfaces is thoroughly examined, shedding light on the influence of the tilt parameter on the transmission probability and the fate of the pseudospin of the Dirac electrons, particularly upon a sudden change in the tilting. We also investigate the probability of reflection and transmission from an intermediate slab with arbitrary subcritical tilt, focusing on the behavior of electron transmission across regions with varying Dirac cone tilts. The study demonstrates that for certain thicknesses of the middle slab, the transmission probability is equal to unity, and both reflection and transmission exhibit periodic behavior with respect to the slab thickness.

cond-mat.mes-hall↗

arXiv2024

Vacancy-induced localized modes and impurity band formation in the Haldane model: a quantum dot analogy

In this study, the Haldane model's edge states are utilized to illustrate that a zero-energy localized state forms around a single vacancy in the model. In order to complete this task, the conventional unit cell associated to the Haldane hexagonal structure is transferred onto a two-leg ladder in momentum space, effectively forming an extended Su-Schrieffer-Heeger~(SSH) lattice through a one-dimensional Fourier transform. Through the application of a suitable unitary transformation, the two-leg SSH ladder in momentum space is converted into an equivalent lattice with two distinct on-site states with different momentum that are suitable for the calculations. Ultimately, the desired zero-energy localized mode formed around the vacant-site is represented by a combination of the armchair edge states. Furthermore, the scenario involving two vacant sites is investigated and it is revealed that an effective hopping interaction exists between the localized states formed around the on-site vacancies created along a zigzag chain in the lattice. This structure can be likened to the structure of a quantum dot with two none-degenerate energy levels. Such a hopping interaction is absent for the same vacancies created on the armchair chains. Finally, it is shown that introducing vacancies periodically on the sites of a zigzag row along a finite-width ribbon with the Haldane structure leads to the emergence of an impurity band within the energy gap.

cond-mat.mes-hall↗