Ultrathin epitaxial graphite was grown on single-crystal silicon carbide by vacuum graphitization. The material can be patterned using standard nanolithography methods. transport properties, which are closely related to those of carbon nanotubes, dominated the single graphene layer at interface and reveal Dirac nature charge carriers. Patterned structures show quantum confinement electrons phase coherence lengths beyond 1 micrometer 4 kelvin, with mobilities exceeding 2.5 square meters per...

We study the electronic structure of two Dirac electron gazes coupled by a periodic Hamiltonian such as it appears in rotated graphene bilayers. Ab initio and tight-binding approaches are combined show that spatially coupling between can renormalize strongly their velocity. investigate particular small angles rotation velocity tends to zero this limit. The localization is confirmed an analysis eigenstates which localized essentially AA zones Moire patterns.

Rotated graphene multilayers form a new class of graphene-related systems with electronic properties that drastically depend on the rotation angles. It has been shown bilayers behave like two isolated planes for large For smaller angles, states in Dirac cones belonging to layers interact resulting appearance Van Hove singularities. States become localized as angle decreases and singularities merge into one peak at energy. Here we go further consider very small In this case, well-defined...

Charge transport in crystalline organic semiconductors is intrinsically limited by the presence of large thermal molecular motions, which are a direct consequence weak van der Waals inter-molecular interactions. These lead to an original regime called \textit{transient localization}, sharing features both localized and itinerant electron systems. After brief review experimental observations that pose challenge theory, we concentrate on commonly studied model describes interaction charge...

High resistivities associated with a reduced density of states and very low effective number carriers are measured in high-structural-quality AlCuFe icosahedral phases. These properties vary strongly composition close to ${\mathrm{Al}}_{63}$${\mathrm{Cu}}_{25}$${\mathrm{Fe}}_{12}$ suggest that insulating quasicrystals could exist. We also show evidence for quantum interference effects the transport diamagnetic susceptibility.

Electronic quantum transport is investigated in boron- and nitrogen-doped carbon nanotubes using tight-binding methods correlated to ab initio calculations. The present technique accurately accounts for both effects of dopants, namely, charge transfer elastic scattering. Generic properties such as conduction mechanisms, mean-free paths, conductance scalings are derived various concentration randomly distributed boron nitrogen dopants. Our calculations allow direct comparison with experiments...

We develop a new real-space method which allows one to evaluate the Kubo-Greenwood formula for dc conductivity of independent electrons in static potential. apply it numerical study propagation modes three dimensional quasiperiodic systems. These are strikingly different from those periodic ones with regard effect disorder. In particular, Fermi energies pseudogaps can be stable or even increase when disorder increases.

The conductivity \ensuremath{\sigma} of a series AlCuFe and AlPdMn quasicrystals approximant phases can be written \ensuremath{\sigma}(T)=${\mathrm{\ensuremath{\sigma}}}_{4}$ K+\ensuremath{\delta}\ensuremath{\sigma}(T). ${\mathrm{\ensuremath{\sigma}}}_{4\mathrm{}\mathrm{K}}$ term is very low, decreases with improvement structural quality, varies strongly composition. \ensuremath{\delta}\ensuremath{\sigma}(T) independent the sample increases anomalously temperature up to 1000 K,...

We present a systematic study of the electronic structure Al-based Hume-Rothery alloys containing transition elements performed with use linear muffin-tin orbital in atomic-sphere approximation method. Our analysis focuses on formation pseudogap at Fermi level leading to stability materials transition-metal small concentration. From self-consistent calculated density states, we observe strong deviation from two classical limits: (a) Friedel-Anderson virtual bond state's model and (b)...

An elastic analog of graphene is introduced and analyzed. The system consists a honeycomb arrangement spring-mass resonators attached to thin layer, the propagation properties flexural waves along it studied. band-structure calculation shows presence Dirac points near $K$ point Brillouin zone. Analytical expressions are found for both frequency velocity as function resonator's parameters. Finally, bounded modes infinitely long ribbons this edge states, which studied using multiple scattering...

A relation derived from the Kubo formula shows that optical conductivity measurements below gap frequency in doped semiconductors can be used to probe directly time-dependent quantum dynamics of charge carriers. This allows extract fundamental quantities such as elastic and inelastic scattering rates, well localization length disordered systems. When applied crystalline organic semiconductors, an incipient electron caused by large dynamical lattice disorder is unveiled, implying a breakdown...

For carbon nanotubes, we determine the role of disorder and helicity in transport length scales intrinsic conductance. Our results highlight different physical phenomena originating from defect scattering multishell conduction. Those effects are sensitive to position Fermi level, allow for a consistent interpretation recent experiments doped nanotubes.

We present an ab initio approach to electronic transport in nanoscale systems which includes correlations through the GW approximation. With respect Landauer approaches based on density-functional theory (DFT), we introduce a physical quasiparticle electronic-structure into non-equilibrium Green's function framework. use equilibrium non-selfconsistent $G^0W^0$ self-energy considering both full non-hermiticity and dynamical effects. The method is applied real system, gold mono-atomic chain....

We report on a numerical study of quantum diffusion over $\ensuremath{\mu}\mathrm{m}$ lengths in defect-free multiwalled nanotubes. The intershell coupling allows the wave packet spreading several shells, and when their periodicities along nanotube axis are incommensurate, electronic propagation is shown to follow nonballistic law if sufficient number shells involved conduction. This results magnetotransport properties which exceptional for disorder free system.

Nanoelectronic devices smaller than the electron wavelength can be achieved in graphene with current lithography techniques. Here we show that electronic quantum transport of subwavelength nanodevices presents deep analogies optics. We introduce concept diffraction barrier to represent effect constrictions and rich phenomena a variety nanodevices. Results are presented for Bethe Kirchhoff slits Fabry-Perot interference oscillations nanoribbons. The same applies dots gives new insight into...

We propose a unified description of transport in graphene with adsorbates that fully takes into account localization effects and loss electronic coherence due to inelastic processes. focus particular on the role scattering properties analyze detail cases resonant or nonresonant scattering. For both models, we identify several regimes conduction, depending value Fermi energy. Sufficiently far from Dirac energy at sufficiently small concentrations, semiclassical theory can be good...

We analyze the quantum transport properties of MAPbI3 within a tight-binding model. Charge carriers are strongly scattered by Fr\"ohlich interaction with longitudinal optical phonon modes. This limits their mobilities at room temperature to order 200 cm$^2$/Vs. In presence additional extrinsic disorder mobility decreases and large fraction electronic states band edges can be localized. These would insulating if lattice were static, but localization is broken dynamic induced vibrations...

Tunneling spectroscopy studies on oxidized and bare surfaces of icosahedral i-AlPdRe, i-AlCuFe, approximant $\ensuremath{\alpha}$-AlMnSi phases reveal specific features the density states (DOS) close to Fermi level as compared crystalline nonapproximant $\ensuremath{\omega}$-AlCuFe phase. The energy lies in middle a narrow pseudogap about 50 meV width. For higher energies, DOS exhibits square root dependence attributed electron-electron interaction effects. differs from linear muffin tin...

We analyze the relationship between tendency to electron localization, which is observed in many quasicrystals and approximants, local atomic order. Starting from structural models, we consider clusters that are embedded a metallic medium, study their scattering properties within multiple-scattering formalism. show these environments can lead virtual bound states for electrons, i.e., resonances of wave function different length scale. That consistent with localization shown by transport...

A model describing the electronic structure of transition metal atoms in Hume-Rothery alloys and quasi-crystals is constructed by adding to classical Anderson Hamiltonian a potential VB(K) that describes diffraction conduction electrons Bragg planes near Fermi surface. Strong deviation from virtual bound state observed for realistic parameters. Furthermore, scattering states d-orbitals changes partial density states. This results contribution apparent negative valency elements alloys. The...

We investigate the properties of electronic states in two- and three-dimensional quasiperiodic structures: generalized Rauzy tilings. Exact diagonalizations, limited to clusters with a few thousands sites, suggest that eigenstates are critical more extended at band edges than center. These trends clearly confirmed when we compute spreading energy-filtered wave packets, using an algorithm allows us treat systems about ${10}^{6}$ sites. The present approach quantum dynamics, which gives also...

Organic solar cells are a promising avenue for renewable energy, and our study introduces comprehensive model to investigate exciton dissociation processes at the donor-acceptor interface. Examining quantum efficiency emitted phonons in charge transfer state (CTS), we explore scenarios like variations of environment beyond CTS repulsive/attractive potentials. The interface significantly influences injection process, with minimal impact from CTS. Attractive potentials can create localized...