Scattering of charge carriers by point defects in bilayer graphene (original) (raw)

Electrons scattering and conductivity in monolayer graphene

Applied Surface Science, 2013

Resonance electronic states and scattering by point defects are studied for the monolayer graphene solving the 2+1-dimensional Dirac equation. Exact S-and T-matrices are calculated for the model potential. This effective potential takes into account possible band asymmetry of the point defect potential matrix elements. Regularization of the scattering problem for a singular potential has been carried out. Asymptotic analysis allowed us to obtain the conductivity dependence on the Fermi level position in the low-energy limit. Numerical calculations were carried out in the wide range of electronic energies. The transport relaxation time behaves as 1/E in the limit of E tending to zero and oscillates around a constant value due to the resonance scattering at higher energy magnitudes.

Effects of lattice defects in graphene on the scattering of Charge Carriers

We study the scattering of graphene quasiparticles by topological defects, represented by holes, pentagons and heptagons. For the case of holes, we obtain the phase shift and found that at low concentration they appear to be irrelevant for the electron transport, giving a negligible contribution to the resistivity. Whenever pentagons are introduced into the lattice and the fermionic current is constrained to move near one of them we realize that such a current is scattered with an angle that depends only on the number of pentagons and on the side the current taken. Such a deviation may be determined by means of a Young-type experiment, through the interference pattern between the two current branches scattered by a pentagon. In the case of a heptagon such a current is also scattered but it diverges from the defect, preventing a interference between two beams of current for the same heptagon. Comment: 7 pages, contribution to 4th International Conference on Fundamental Interactions A...

Electrons scattering in the monolayer graphene with the short-range impurities

Physics Letters A, 2010

Electron scattering in the monolayer graphene with short-range impurities modelled by the annular well with a band-asymmetric potential has been considered. Band-asymmetry of the potential resulted in the mass (gap) perturbation in the Dirac equation. Exact explicit formulae for the scattering matrix have been derived. The results are presented in terms of the scattering phases and in the geometrical form of a relation between some 2-vectors. The characteristic equation is obtained. It has a form of the orthogonality condition. An approximate calculation of observables in terms the scattering theory results is outlined.

Electron scattering on microscopic corrugations in graphene

2008

We discuss various scattering mechanisms for Dirac fermions in single-layer graphene. It is shown that scattering on a short-range potential (due to, for example, neutral impurities) is mostly irrelevant for electronic quality of graphene, which is likely to be controlled by charged impurities and ripples (microscopic corrugations of a graphene sheet). The latter are an inherent feature of graphene due to its two-dimensional nature and can also be an important factor in defining the electron mean free path. We show that certain types of ripples create a long-range scattering potential, similar to Coulomb scatterers, and result in charge-carrier mobility practically independent on carrier concentration, in agreement with experimental observations.

Electron scattering in the monolayer graphene with a band-asymmetric annular potential well

Physics of the Solid State, 2011

Scattering of charge carriers in graphene induced by topological defects

2010

We study a kind of gravitational Aharonov-Bohm effect in a graphene sheet with a wedge removed and edges identified, i.e., a graphitic cone. The angular defect gives rise to a mismatch of the components of the graphene's relativistic charged quasiparticle wavefunctions (spinors) upon closed parallel transport around the (singular) cone tip. Such an effect should affect the basic electronic properties in "conical graphenes" as compared with their planar counterpart and it could be, in principle, detected experimentally. Measurements of the electronic transport in these graphitic materials and their relationships with the changes calculated in the quasiparticle wavefunctions could make available interesting probes to the Einstein theory of general relativity in two spatial dimensions. Therefore, we propose a way of verifying, in a microscopic scale, some predictions of a theory that is usually associated with incredible large objects such as planets, stars, black holes, galaxies and so on.

Electron scattering in graphene by impurities with electric and magnetic dipole moments

Physica E: Low-dimensional Systems and Nanostructures, 2014

The scattering of electrons by deferent scatterers in graphene has been intensively studied since its experimental discovery [1]. The main characteristic of graphene is that its electrons are described by the Dirac's like equation for massless particles [2]. This results in the linear dispersion of the electron energy on the wave vector and in very high electron mobility [3]. The main result of these studies of electron scattering in graphene through different mechanisms with radially symmetric potentials is the absence of the back scattering [4-7].

Effect of the Coulomb scattering on graphene conductivity

JETP Letters, 2008

The effect of Coulomb scattering on graphene conductivity in field effect transistor structures is discussed. Inter-particle scattering (electron-electron, hole-hole, and electron-hole) and scattering on charged defects are taken into account in a wide range of gate voltages. It is shown that an intrinsic conductivity of graphene (purely ambipolar system where both electron and hole densities exactly coincide) is defined by strong electron-hole scattering. It has a universal value independent of temperature. We give an explicit derivation based on scaling theory. When there is even a small discrepancy in electron and hole densities caused by applied gate voltage the conductivity is determined by both strong electron-hole scattering and weak external scattering: on defects or phonons. We suggest that a density of charged defects (occupancy of defects) depends on Fermi energy to explain a sub-linear dependence of conductivity on a fairly high gate voltage observed in experiments. We also eliminate contradictions between experimental data obtained in deposited and suspended graphene structures regarding graphene conductivity.

Theory of charged impurity scattering in two-dimensional graphene

Solid State Communications, 2009

We review the physics of charged impurities in the vicinity of graphene. The long-range nature of Coulomb impurities affects both the nature of the ground state density profile as well as graphene's transport properties. We discuss the screening of a single Coulomb impurity and the ensemble averaged density profile of graphene in the presence of many randomly distributed impurities. Finally, we discuss graphene's transport properties due to scattering off charged impurities both at low and high carrier density.

Scattering theory and ground-state energy of Dirac fermions in graphene with two Coulomb impurities

The European Physical Journal B, 2014

We study the physics of Dirac fermions in a gapped graphene monolayer containing two Coulomb impurities. For the case of equal impurity charges, we discuss the ground-state energy using the linear combination of atomic orbitals (LCAO) approach. For opposite charges of the Coulomb centers, an electric dipole potential results at large distances. We provide a nonperturbative analysis of the corresponding low-energy scattering problem.

Scattering of charge carriers by point defects in bilayer graphene (original) (raw)

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