Related papers: Triplet excitations in graphene-based systems
We show that the emergent relativistic symmetry of electrons in graphene near its quantum critical point (QCP) implies a crucial importance of the Coulomb interaction. We derive scaling laws, valid near the QCP, that dictate the nontrivial…
Collective excitations of coupled electron-phonon systems are calculated for both monolayer and bilayer graphene, taking into account the non-perturbative Coulomb coupling between electronic excitations in graphene and the substrate…
We investigate the addition spectrum of a graphene quantum dot in the vicinity of the electron-hole crossover as a function of perpendicular magnetic field. Coulomb blockade resonances of the 50 nm wide dot are visible at all gate voltages…
We analyze charging effects in graphene quantum dots. Using a simple model, we show that, when the Fermi level is far from the neutrality point, charging effects lead to a shift in the electrostatic potential and the dot shows standard…
Recent fluorescence spectroscopy experiments on single wall carbon nanotubes reveal substantial deviations of observed absorption and emission energies from predictions of noninteracting models of the electronic structure. Nonetheless, the…
We present transport measurements on a tunable three-layer graphene single electron transistor (SET). The device consists of an etched three-layer graphene flake with two narrow constrictions separating the island from source and drain…
We present electron transport measurements on lithographically defined and etched graphene nanoconstrictions with different aspect ratios including different lengths (L) and widths (W). A roughly length-independent disorder induced…
Coulomb interaction is of central importance in localized energy levels (bound states) or electronic flat bands and could result in many exotic quantum phases, such as magnetic, superconducting, and topological phases in graphene…
We investigate the problem of dynamical gap generation in suspended graphene by long-range Coulomb interactions at strong coupling with Dyson-Schwinger equations. Including renormalization effects on the Fermi velocity we obtain a critical…
We analyze the phase diagram of twisted graphene bilayers near a magic angle. We consider the effect of the long range Coulomb interaction, treated within the self consistent Hartree-Fock approximation, and we study arbitrary band fillings.…
We report the observation of Coulomb drag between a two-dimensional (2D) electron gas in graphene and a one-dimensional (1D) wire composed of a carbon nanotube. We find that drag occurs when the bulk of graphene is conducting, but is…
We show that the energy differences between the lowest optical singlet exciton and the lowest triplet exciton in semiconducting single-walled carbon nanotubes with diameter $\sim 1$ nm and graphene nanoribbons with widths $\sim 2$ nm are an…
We show that in a two-dimensional electron gas with an annular Fermi surface, long-range Coulomb interactions can lead to unconventional superconductivity by the Kohn-Luttinger mechanism. Superconductivity is strongly enhanced when the…
Coupled electron-hole states are realized in a system consisting of a combination of an electrostatic potential barrier and ring-shaped potential well, which resembles a circular dipole. A perpendicular magnetic field induces confined…
A doped graphene layer in the integer quantum Hall regime reveals a highly unusual particle-hole excitation spectrum, which is calculated from the dynamical polarizability in the random phase approximation. We find that the elementary…
The intrinsic Zeeman energy is precisely one half of the cyclotron energy for electrons in graphene. As a result a Landau-level mixing occurs to create the energy spectrum comprised of the $4j$-fold degenerated zero-energy level and 4-fold…
We consider a waveguide formed in a clean graphene monolayer by a spatially inhomogeneous magnetic field. The single-particle dispersion relation for this waveguide exhibits a zero-energy Landau-like flat band, while finite-energy bands…
The physics of non-local exchange interactions in graphene sheets is studied within a $\pi$-orbital tight-binding model using a Hartree-Fock approximation and Coulomb interactions modified at short distances by lattice effects and at large…
In this paper we study the excitation spectrum of single- and multi-layer graphene beyond the Dirac cone approximation. The dynamical polarizability of graphene is computed using a full $\pi$-band tight-binding model, considering the…
Graphene is a two-dimensional carbon material with a honeycomb lattice and Dirac-type low-energy spectrum. In a strong magnetic field, where Coulomb interactions dominate against disorder broadening, quantum Hall ferromagnetic states…