Jean-Noël Fuchs

Merging of Dirac points in a two-dimensional crystal

We study under which general conditions a pair of Dirac points in the electronic spectrum of a twodimensional crystal may merge into a single one. The merging signals a topological transition between a semimetallic phase and a band insulator. We derive a universal Hamiltonian that describes the physical properties of the transition, which is controlled by a single parameter, and analyze the Landau-level spectrum in its

Tilted anisotropic Dirac cones in quinoid-type graphene and α − ( BEDT-TTF ) 2 I 3

We investigate a generalized two-dimensional Weyl Hamiltonian, which may describe the low-energy properties of mechanically deformed graphene and of the organic compound

A universal Hamiltonian for motion and merging of Dirac points in a two-dimensional crystal

\ensuremath{\alpha}\text{\ensuremath{-}}{(\text{BEDT-TTF})}_{2}{\text{I}}_{3}

Filling-factor-dependent magnetophonon resonance in graphene

[\text{BEDT-TTF}=\text{bis}(\text{ethylene}\text{dithio)tetrathiafulvalene}]

Comparative spectra and efficiencies of ions laser-accelerated forward from the front and rear surfaces of thin solid foils

under pressure. The associated dispersion has generically the form of tilted anisotropic Dirac cones. The tilt arises due to next-nearest-neighbor hopping when the Dirac points, where the valence band touches the conduction band, do not coincide with crystallographic high-symmetry points within the first Brillouin zone. Within a semiclassical treatment, we describe the formation of Landau levels in a strong magnetic field, the relativistic form of which is reminiscent of that of graphene, with a renormalized Fermi velocity due to the tilt of the Dirac cones. These relativistic Landau levels, experimentally accessible via spectroscopy or even a quantum-Hall-effect measurement, may be used as a direct experimental verification of Dirac cones in

Exactly Solvable Model of the BCS-BEC Crossover

\ensuremath{\alpha}\text{\ensuremath{-}}{(\text{BEDT-TTF})}_{2}{\text{I}}_{3}

Bloch-Zener oscillations across a merging transition of Dirac points.

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The magnetic field particle–hole excitation spectrum in doped graphene and in a standard two-dimensional electron gas

AbstractWe propose a simple Hamiltonian to describe the motion and the merging of Dirac points in the electronic spectrum of two-dimensional electrons. This merging is a topological transition which separates a semi-metallic phase with two Dirac cones from an insulating phase with a gap. We calculate the density of states and the specific heat. The spectrum in a magnetic field B is related to the resolution of a Schrödinger equation in a double well potential. The Landau levels obey the general scaling law epsilonn ∝B2/3 fn(Δ/B2/3), and they evolve continuously from a

Internal state conversion in ultracold gases.

\sqrt{n B}