553 research outputs found
Luttinger liquids with curvature: Density correlations and Coulomb drag effect
We consider the effect of the curvature in fermionic dispersion on the
observable properties of Luttinger liquid (LL). We use the bosonization
technique where the curvature is irrelevant perturbation, describing the decay
of LL bosons (plasmon modes). When possible, we establish the correspondence
between the bosonization and the fermionic approach. We analyze modifications
in density correlation functions due to curvature at finite temperatures, T.
The most important application of our approach is the analysis of the Coulomb
drag by small momentum transfer between two LL, which is only possible due to
curvature. Analyzing the a.c. transconductivity in the one-dimensional drag
setup, we confirm the results by Pustilnik et al. for T-dependence of drag
resistivity, R_{12} ~ T^2 at high and R_{12} ~ T^5 at low temperatures. The
bosonization allows for treating both intra- and inter-wire electron-electron
interactions in all orders, and we calculate exact prefactors in low-T drag
regime. The crossover temperature between the two regimes is T_1 ~ E_F \Delta,
with \Delta relative difference in plasmon velocities. We show that \Delta \neq
0 even for identical wires, due to lifting of degeneracy by interwire
interaction, U_{12}, leading to crossover from R_{12} ~ U_{12}^2 T^2 to R_{12}
\~ T^5/U_{12} at T ~ U_{12}.Comment: 16 pages, 10 figures, REVTE
The fate of 1D spin-charge separation away from Fermi points
We consider the dynamic response functions of interacting one dimensional
spin-1/2 fermions at arbitrary momenta. We build a non-perturbative
zero-temperature theory of the threshold singularities using mobile impurity
Hamiltonians. The interaction induced low-energy spin-charge separation and
power-law threshold singularities survive away from Fermi points. We express
the threshold exponents in terms of the spinon spectrum.Comment: 5 pages, 1 figur
Influences of an impurity on the transport properties of one-dimensional antisymmetric spin filter
The influences of an impurity on the spin and the charge transport of
one-dimensional antisymmetric spin filter are investigated using bosonization
and Keldysh formulation and the results are highlighted against those of
spinful Luttinger liquids. Due to the dependence of the electron spin
orientation on wave number the spin transport is not affected by the impurity,
while the charge transport is essentially identical with that of spinless
one-dimensional Luttinger liquid.Comment: 7 pages, 2 figures. To appear in Physical Review
The Fermi edge singularity in the SU(N) Wolff model
The low temperature properties of the SU(N) Wolff impurity model are studied
via Abelian bosonization. The path integral treatment of the problem allows for
an exact evaluation of low temperature properties of the model. The single
particle Green's function enhances due to the presence of local correlation.
The basic correlation function such as the charge or spin correlator are also
influenced by the presence of impurity, and show local Fermi liquid behaviour.
The X-ray absorption is affected by the presence of local Hubbard interaction.
The exponent is decreased (increased) for repulsive (attractive) interactions.Comment: 7 pages, 4 figure
Spin-filtering by field dependent resonant tunneling
We consider theoretically transport in a spinfull one-channel interacting
quantum wire placed in an external magnetic field. For the case of two
point-like impurities embedded in the wire, under a small voltage bias the
spin-polarized current occurs at special points in the parameter space, tunable
by a single parameter. At sufficiently low temperatures complete
spin-polarization may be achieved, provided repulsive interaction between
electrons is not too strong.Comment: 4 pages, 2 figure
Interactions suppress Quasiparticle Tunneling at Hall Bar Constrictions
Tunneling of fractionally charged quasiparticles across a two-dimensional
electron system on a fractional quantum Hall plateau is expected to be strongly
enhanced at low temperatures. This theoretical prediction is at odds with
recent experimental studies of samples with weakly-pinched
quantum-point-contact constrictions, in which the opposite behavior is
observed. We argue here that this unexpected finding is a consequence of
electron-electron interactions near the point contact.Comment: 4 page
Transverse spectral functions and Dzyaloshinskii-Moriya interactions in XXZ spin chains
Recently much progress has been made in applying field theory methods, first
developed to study X-ray edge singularities, to interacting one dimensional
systems in order to include band curvature effects and study edge singularities
at arbitrary momentum. Finding experimental confirmations of this theory
remains an open challenge. Here we point out that spin chains with uniform
Dzyaloshinskii-Moriya (DM) interactions provide an opportunity to test these
theories since these interactions may be exactly eliminated by a gauge
transformation which shifts the momentum. However, this requires an extension
of these X-ray edge methods to the transverse spectral function of the xxz spin
chain in a magnetic field, which we provide
Susceptibility at the edge points of magnetization plateau of 1D electron/spin systems
We study the behavior of magnetization curve as a function of magnetic field
in the immediate vicinity of the magnetization plateaus of 1D electron systems
within the bosonization formalism. First we discuss the plateau that is formed
at the saturation magnetization of 1D electron system. Interactions between
electrons we treat in the lowest order of perturbation. We show that for
isolated systems, where total number of electrons is not allowed to vary,
magnetic susceptibility stays always finite away of half filling. Similar
statement holds for many other magnetization plateaus supporting nonmagnetic
gapless excitations encountered in 1D electron/spin systems in the absence of
special symmetries or features responsible for the mode decoupling. We
demonstrate it on example of the plateaus at irrational values of magnetization
in doped modulated Hubbard chains. Finally we discuss the connection between
the weak coupling description of saturation magnetization plateau and strong
coupling description of zero magnetization plateau of attractively interacting
electrons/ antiferromagnetically interacting spin 1 Bosons.Comment: 10 pages, 3 figures. To appear in Phys. Rev.
Collective excitation of quantum wires and effect of spin-orbit coupling in the presence of a magnetic field along the wire
The band structure of a quantum wire with the Rashba spin-orbit coupling
develops a pseudogap in the presence of a magnetic field along the wire. In
such a system spin mixing at the Fermi wavevectors and can be
different. We have investigated theoretically the collective mode of this
system, and found that the velocity of this collective excitation depends
sensitively on the strength of the Rashba spin-orbit interaction and magnetic
field. Our result suggests that the strength of the spin-orbit interaction can
be determined from the measurement of the velocity.Comment: RevTeX 4 file, 4pages, 6 eps figures. To appear in Physical Review
Localization of a matter wave packet in a disordered potential
We theoretically study the Anderson localization of a matter wave packet in a
one-dimensional disordered potential. We develop an analytical model which
includes the initial phase-space density of the matter wave and the spectral
broadening induced by the disorder. Our approach predicts a behavior of the
localized density profile significantly more complex than a simple exponential
decay. These results are confirmed by large-scale and long-time numerical
calculations. They shed new light on recent experiments with ultracold atoms
and may impact their analysis
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