Related papers: Existence and merging of Dirac points in $\alpha$-…
The Dirac electron in the organic conductor $\alpha$-(BEDT-TTF)$_2$I$_3$ under pressure is analyzed using a tight-binding model with nearest-neighbor transfer energies and four molecules per unit cell. By noting that the Dirac point between…
By examining organic conductor alpha-(BEDT-TTF)_2I_3 which is described by a nearest neighbors tight-binding model it is shown that because of inversion symmetry, each component of a wave function (WF) exhibits nodal lines (NLs) in the…
We re-examine the band structure of the stripe charge ordered state of $\alpha$-(BEDT-TTF)$_2$I$_3$ under pressure by using an extended Hubbard model within the Hartree mean-field theory. By increasing pressure, we find a topological…
The energies as a function of the magnetic field ($H$) and the pressure are studied theoretically in the tight-binding model for the two-dimensional organic conductor, $\alpha$-(BEDT-TTF)$_2$I$_3$, in which massless Dirac fermions are…
Dirac electrons in a single-component molecular conductor [Pd(dddt)$_2$] under pressure have been examined using a tight-binding model which consists of HOMO (Highest Occupied Molecular Orbital) and LUMO (Lowest Unoccupied Molecular…
We study the algebraic structure of the Dirac fermion state in the organic conductor, \alpha-(BDET-TTF)_2I_3. We find a pair of generators for the Hamiltonian of \alpha-(BDET-TTF)_2I_3 that describes the chirality of Dirac fermions. The…
We examine several properties of the Berry curvature for the organic conductor $\alpha$-(BEDT-TTF)$_2$I$_3$ consisting of four bands, which exhibits a zero-gap state with Dirac cones. By adding a small potential acting on two molecular…
We study under which general conditions a pair of Dirac points in the electronic spectrum of a two-dimensional crystal may merge into a single one. The merging signals a topological transition between a semi-metallic phase and a band…
We consider the optical and transport properties in a model two-dimensional Hamiltonian which describes the merging of two Dirac points. At low energy, in the presence of an energy gap parameter $\Delta$, there are two distinct Dirac points…
We investigate the pressure effect on the layered Dirac fermion system, which is realized in quasi-two-dimensional organic compound {\alpha}-(BEDT-TTF)2I3. The trajectory of the contact points is investigated using the tight-binding model…
In a Dirac semimetal, the conduction and valence bands contact only at discrete (Dirac) points in the Brillouin zone (BZ) and disperse linearly in all directions around these critical points. Including spin, the low energy effective theory…
The spectrum of tight binding electrons on a square lattice with half a magnetic flux quantum per unit cell exhibits two Dirac points at the band center. We show that, in the presence of an additional uniaxial staggered potential, this pair…
The manipulation and movement of Dirac points in the Brillouin zone by the electron-electron interaction is considered within leading order perturbation theory. At the merging point, an infinitesimal interaction is shown to cause opening of…
In most Dirac semimetals, time-reversal and inversion symmetries are believed to play a crucial role in their stability. We demonstrate that these symmetries are broken in Dirac fermions in the organic conductor $\alpha$-(BEDT-TTF)$_2$I$_3$…
Dirac points lie at the heart of many fascinating phenomena in condensed matter physics, from massless electrons in graphene to the emergence of conducting edge states in topological insulators [1, 2]. At a Dirac point, two energy bands…
Dirac electrons with a zero-gap state (ZGS) in organic conductor $\alpha$-(BEDT-TTF)$_2$I$_3$ result from a fine tuning of the seven nearest neighbors transfer integrals ($a_1, a_2, a_3, b_1, b_2, b_3, b_4$) between the four molecules of…
We employed first-principles density-functional theory (DFT) calculations to characterize Dirac electrons in quasi-two-dimensional molecular conductor $\alpha$-(BETS)$_2$I$_3$ [= $\alpha$-(BEDT-TSeF)$_2$I$_3$] at a low temperature of 30K.…
We study the massless Dirac field on the line in the presence of a point-like defect characterised by a unitary scattering matrix, that allows both reflection and transmission. Considering this system in its ground state, we derive the…
The identification of novel multifunctional Dirac materials has been an ongoing effort. In this connection quasi 2-dimensional (BEDT-TTF)-based charge transfer salts are widely discussed. Here, we report about the electronic structure of…
A continuous deformation of a Hamiltonian possessing at low energy two Dirac points of opposite chiralities can lead to a gap opening by merging of the two Dirac points. In two dimensions, the critical Hamiltonian possesses a semi-Dirac…