144 research outputs found
Chiral sound waves in strained Weyl semimetals
We show that a strained wire of a Weyl semimetal supports a new type of
gapless excitation, the chiral sound wave (CSW). It is a longitudinal charge
density wave analog to the chiral magnetic wave predicted in the quark-gluon
plasma but driven by an elastic axial pseudo-magnetic field. It involves the
axial-axial-axial contribution to the chiral anomaly which couples the chiral
charge density to the elastic axial gauge field. The chiral sound is
unidirectional: it propagates along the elastic magnetic field and not in the
opposite direction. The CSW may propagate for long distances as it does not
couple directly to quickly dissipating electromagnetic plasmons, while its
damping is controlled by the slow chirality flip rate. We propose an
experimental setup to directly detect the chiral sound, which is excited by
mechanical vibrations of the crystal lattice in the GHz frequency range. Our
findings contribute to a new trend, the chiral acoustics, in strained Weyl
semimetals.Comment: 5 pages, 3 figures; v2: minor changes, published versio
Gauge fields in graphene
The physics of graphene is acting as a bridge between quantum field theory
and condensed matter physics due to the special quality of the graphene
quasiparticles behaving as massless two dimensional Dirac fermions. Moreover,
the particular structure of the 2D crystal lattice sets the arena to study and
unify concepts from elasticity, topology and cosmology. In this paper we
analyze these connections combining a pedagogical, intuitive approach with a
more rigorous formalism when required.Comment: Update of the manuscript published on-line in Physics Reports. 43
pages, 18 figure
Renormalization group analysis of electrons near a Van Hove singularity.
A model of interacting two dimensional electrons near a Van Hove singularity
is studied, using renormalization group techniques. In hole doped systems, the
chemical potential is found to be pinned near the singularity, when the
electron-electron interactions are repulsive. The RG treatment of the leading
divergences appearing in perturbation theory give rise to marginal behavior and
anisotropic superconductivity.Comment: 4 Latex pages + 5 postcript figure
Electrostatic screening in fullerene molecules
The screening properties of fullerene molecules are described by means of a
continuum model which uses the electronic wavefunctions of planar graphite as a
starting point. The long distance behavior of the system gives rise to a
renormalizable theory, which flows towards a non trivial fixed point. Its
existence implies an anomalous dielectric constant. The screening properties
are neither metallic nor insulating. Alternatively, the intramolecular
screening is obtained from a simple approximation to the electronic
wavefunctions. Intermolecular effects are also calculated. As a consistency
check, it is shown that the observed polarizability of C is well
eproduced.Comment: 7 pages. Revte
Long-range-correlated disorder in graphene
We study transport of two-dimensional quasi-relativistic electronic
excitations in graphene in the presence of static long-range-correlated random
scalar and vector potentials. Using a combination of perturbation theory and
path-integral techniques, we estimate scattering rates which control Drude
conductivity, magneto-transport, and Friedel oscillations in the ballistic
regime of large quasiparticle energies. We also discuss properties of
zero-energy states and pertinent localization scenarios.Comment: 4 pages, Latex, no figure
Transverse transport in graphite
Graphite is a layered material showing a strong anisotropy. Among the
unconventional properties reported by experiments, the electronic transport
along the c-axis, which has direct implications in order to build graphitic
devices, remains a controversial topic. We study the influence of inelastic
scattering on the electron tunnelling between layers. In the presence of
electron electron interactions, tunnelling processes are modified by inelastic
scattering events.Comment: 9 pages, no figures Proceedings of the Graphene Conference, MPI PKS
Dresden, September 200
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