8,046 research outputs found
Ballistic charge transport in chiral-symmetric few-layer graphene
A transfer matrix approach to study ballistic charge transport in few-layer
graphene with chiral-symmetric stacking configurations is developed. We
demonstrate that the chiral symmetry justifies a non-Abelian gauge
transformation at the spectral degeneracy point (zero energy). This
transformation proves the equivalence of zero-energy transport properties of
the multilayer to those of the system of uncoupled monolayers. Similar
transformation can be applied in order to gauge away an arbitrary magnetic
field, weak strain, and hopping disorder in the bulk of the sample. Finally, we
calculate the full-counting statistics at arbitrary energy for different
stacking configurations. The predicted gate-voltage dependence of conductance
and noise can be measured in clean multilayer samples with generic metallic
leads.Comment: 6 pages, 5 figures; EPL published versio
Plasmonic shock waves and solitons in a nanoring
We apply the hydrodynamic theory of electron liquid to demonstrate that a
circularly polarized radiation induces the diamagnetic, helicity-sensitive dc
current in a ballistic nanoring. This current is dramatically enhanced in the
vicinity of plasmonic resonances. The resulting magnetic moment of the nanoring
represents a giant increase of the inverse Faraday effect. With increasing
radiation intensity, linear plasmonic excitations evolve into the strongly
non-linear plasma shock waves. These excitations produce a series of the well
resolved peaks at the THz frequencies. We demonstrate that the plasmonic wave
dispersion transforms the shock waves into solitons. The predicted effects
should enable multiple applications in a wide frequency range (from the
microwave to terahertz band) using optically controlled ultra low loss
electric, photonic and magnetic devices.Comment: 13 pages, 12 figure
Elastic forward scattering in the cuprate superconducting state
We investigate the effect of elastic forward scattering on the ARPES spectrum
of the cuprate superconductors. In the normal state, small angle scattering
from out-of-plane impurities is thought to broaden the ARPES spectral response
with minimal effect on the resistivity or the superconducting transition
temperature . Here we explore how such forward scattering affects the
ARPES spectrum in the d-wave superconducting state. Away from the nodal
direction, the one-electron impurity scattering rate is found to be suppressed
as approaches the gap edge by a cancellation between normal and
anomalous scattering processes, leading to a square-root-like feature in the
spectral weight as approaches -\Delta_\k from below. For momenta
away from the Fermi surface, our analysis suggests that a dirty optimally or
overdoped system will still display a sharp but nondispersive peak which could
be confused with a quasiparticle spectral feature. Only in cleaner samples
should the true dispersing quasiparticle peak become visible. At the nodal
point on the Fermi surface, the contribution of the anomalous scattering
vanishes and the spectral weight exhibits a Lorentzian quasiparticle peak in
both energy and momentum.
Our analysis, including a treatment of unitary scatterers and inelastic spin
fluctuation scattering, suggests explanations for the sometimes mysterious
lineshapes and temperature dependences of the peak structures observed in the
\BSCCO system.Comment: 12 pages, 14 figure
The influence of Galactic aberration on precession parameters determined from VLBI observations
The influence of proper motions of sources due to Galactic aberration on
precession models based on VLBI data is determined. Comparisons of the linear
trends in the coordinates of the celestial pole obtained with and without
taking into account Galactic aberration indicate that this effect can reach 20
as per century, which is important for modern precession models. It is
also shown that correcting for Galactic aberration influences the derived
parameters of low-frequency nutation terms. It is therefore necessary to
correct for Galactic aberration in the reduction of modern astrometric
observations
Andreev levels in a single-channel conductor
We calculate the subgap density of states of a disordered single-channel
normal metal connected to a superconductor at one end (NS junction) or at both
ends (SNS junction). The probability distribution of the energy of a bound
state (Andreev level) is broadened by disorder. In the SNS case the two-fold
degeneracy of the Andreev levels is removed by disorder leading to a splitting
in addition to the broadening. The distribution of the splitting is given
precisely by Wigner's surmise from random-matrix theory. For strong disorder
the mean density of states is largely unaffected by the proximity to the
superconductor, because of localization, except in a narrow energy region near
the Fermi level, where the density of states is suppressed with a log-normal
tail.Comment: 12 pages, 5 figure
Hyperon production in near threshold nucleon-nucleon collisions
We study the mechanism of the associated Lambda-kaon and Sigma-kaon
production in nucleon-nucleon collisions over an extended range of near
threshold beam energies within an effective Lagrangian model, to understand of
the new data on pp --> p Lambda K+ and pp --> p Sigma0 K+ reactions published
recently by the COSY-11 collaboration. In this theory, the hyperon production
proceeds via the excitation of N*(1650), N*(1710), and N*(1720) baryonic
resonances. Interplay of the relative contributions of various resonances to
the cross sections, is discussed as a function of the beam energy over a larger
near threshold energy domain. Predictions of our model are given for the total
cross sections of pp --> p Sigma+K0, pp --> n Sigma+K+, and pn --> n Lambda K+
reactions.Comment: 16 pages, 4 figures, one new table added and dicussions are updated,
version accepted for publication by Physical Review
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