218 research outputs found
Integral charge quasiparticles in a fractional quantum Hall liquid
Starting from a collective description of the incompressible fractional
quantum Hall liquid as an elastic medium that supports gapped neutral
excitations I show that the one-electron spectral function of this system
exhibits a sharp peak at the lowest available excitation energy, well separated
from the continuum spectrum at higher energy. I interpret this peak as the
signature of the integral charge quasiparticle recently predicted by Peterson
and Jain\cite{Jain05}, and calculate its spectral weight for different filling
factors.Comment: 4 pages, 2 figure
Spin dynamics from time-dependent spin density-functional theory
We derive the spin-wave dynamics of a magnetic material from the
time-dependent spin density functional theory in the linear response regime.
The equation of motion for the magnetization includes, besides the static spin
stiffness, a "Berry curvature" correction and a damping term. A gradient
expansion scheme based on the homogeneous spin-polarized electron gas is
proposed for the latter two quantities, and the first few coefficients of the
expansion are calculated to second order in the Coulomb interaction.Comment: 8 pages, no figure
Spin Drag and Spin-Charge Separation in Cold Fermi Gases
Low-energy spin and charge excitations of one-dimensional interacting
fermions are completely decoupled and propagate with different velocities.
These modes however can decay due to several possible mechanisms. In this paper
we expose a new facet of spin-charge separation: not only the speeds but also
the damping rates of spin and charge excitations are different. While the
propagation of long-wavelength charge excitations is essentially ballistic,
spin propagation is intrinsically damped and diffusive. We suggest that cold
Fermi gases trapped inside a tight atomic waveguide offer the opportunity to
measure the spin-drag relaxation rate that controls the broadening of a spin
packet.Comment: 4 pages, 4 figures, submitte
The intrinsic charge and spin conductivities of doped graphene in the Fermi-Liquid regime
The experimental availability of ultra-high-mobility samples of graphene
opens the possibility to realize and study experimentally the "hydrodynamic"
regime of the electron liquid. In this regime the rate of electron-electron
collisions is extremely high and dominates over the electron-impurity and
electron-phonon scattering rates, which are therefore neglected. The system is
brought to a local quasi-equilibrium described by a set of smoothly varying (in
space and time) functions, {\it i.e.} the density, the velocity field and the
local temperature. In this paper we calculate the charge and spin
conductivities of doped graphene due solely to electron-electron interactions.
We show that, in spite of the linear low-energy band dispersion, graphene
behaves in a wide range of temperatures as an effectively Galilean invariant
system: the charge conductivity diverges in the limit , while the spin
conductivity remains finite. These results pave the way to the description of
charge transport in graphene in terms of Navier-Stokes equations.Comment: 19 pages, 7 figures. arXiv admin note: text overlap with
arXiv:1406.294
Quantum Breathing Mode for Electrons with 1/r^2 Interaction
We discuss a collective "breathing" mode of electrons with inverse-square-law
interactions in a two-dimensional quantum dot and a perpendicular magnetic
field.Comment: 1 page, Revtex, submitted to "Comment" Section of Phys. Rev. Let
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