2,404 research outputs found
DC--Transport in Quantum Wires
The influence of electron--electron interaction on two terminal DC
conductance of one--dimensional quantum wires is studied. A cancelation between
the effect of the electron--electron interaction on the current and on the
external electric field is the reason for the universal value,
per mode, of the DC conductance of a clean wire. The effect of the
renormalization of the electric field on the DC conductance in the presence of
an interplay between the electron--electron interaction and backward scattering
due to an impurity is considered.Comment: 11 Pages, Revte
Spin and interaction effects on charge distribution and currents in one-dimensional conductors and rings within the Hartree-Fock approximation
Using the self--consistent Hartree-Fock approximation for electrons with spin
at zero temperature, we study the effect of the electronic interactions on the
charge distribution in a one-dimensional continuous ring containing a single
scatterer. We reestablish that the interaction suppresses the decay
of the Friedel oscillations. Based on this result, we show that in an infinite
one dimensional conductor containing a weak scatterer, the current is totally
suppressed because of a gap opened at the Fermi energy. In a canonical ensemble
of continuous rings containing many scatterers, the interactions enhance the
average and the typical persistent current.Comment: 5 pages, 4 figure
Bag Formation in Quantum Hall Ferromagnets
Charged skyrmions or spin-textures in the quantum Hall ferromagnet at filling
factor nu=1 are reinvestigated using the Hartree-Fock method in the lowest
Landau level approximation. It is shown that the single Slater determinant with
the minimum energy in the unit charge sector is always of the hedgehog form. It
is observed that the magnetization vector's length deviates locally from unity,
i.e. a bag is formed which accommodates the excess charge. In terms of a
gradient expansion for extended spin-textures a novel O(3) type of effective
action is presented, which takes bag formation into account.Comment: 13 pages, 3 figure
Conductance Increase by Electron-Phonon Interaction in Quantum Wires
We investigate the influence of electron-phonon interactions on the
DC-conductance of a quantum wire in the limit of one occupied
subband. At zero temperature, a Tomonaga-Luttinger-like renormalization of
to a value slightly larger than is calculated for a
realistic quantum wire model.Comment: 12 pages RevTeX, no figure. Appears in Phys. Rev.
From Tomonaga-Luttinger to Fermi liquid in transport through a tunneling barrier
Finite length of a one channel wire results in crossover from a
Tomonaga-Luttinger to Fermi liquid behavior with lowering energy scale. In
condition that voltage drop mostly occurs across a tunnel barrier inside
the wire we found coefficients of temperature/voltage expansion of low energy
conductance as a function of constant of interaction, right and left traversal
times. At higher voltage the finite length contribution exhibits oscillations
related to both traversal times and becomes a slowly decaying correction to the
scale-invariant dependence of the conductance.Comment: 12 pages of RevTex file and 1 PS file figur
Transport properties of a quantum wire in the presence of impurities and long-range Coulomb forces
One-dimensional electron systems interacting with long-range Coulomb forces
(quantum wires) show a Wigner crystal structure. We investigate in this paper
the transport properties of such a Wigner crystal in the presence of
impurities. Contrary to what happens when only short-range interactions are
included, the system is dominated by scattering on the impurities.
There are two important length scales in such a problem: one is the pinning
length above which the (quasi-)long-range order of the Wigner crystal is
destroyed by disorder. The other length is the length below which
Coulomb interactions are not important and the system is behaving as a standard
Luttinger liquid with short-range interactions. We obtain the frequency and
temperature dependence of the conductivity. We show that such a system is very
similar to a classical charge density wave pinned by impurities, but with
important differences due to quantum fluctuations and long-range Coulomb
interactions. Finally we discuss our results in comparison with experimental
systems.Comment: 25 pages, RevTex3.
The TIANSHAN Radio Experiment for Neutrino Detection
An antenna array devoted to the autonomous radio-detection of high energy
cosmic rays is being deployed on the site of the 21 cm array radio telescope in
XinJiang, China. Thanks in particular to the very good electromagnetic
environment of this remote experimental site, self-triggering on extensive air
showers induced by cosmic rays has been achieved with a small scale prototype
of the foreseen antenna array. We give here a detailed description of the
detector and present the first detection of extensive air showers with this
prototype.Comment: 37 pages, 15 figures. Astroparticle Physics (in press
Spin polarons in triangular antiferromagnets
The motion of a single hole in a 2D triangular antiferromagnet is
investigated using the t-J model. The one-hole states are described by strings
of spin deviations around the hole. Using projection technique the one-hole
spectral function is calculated. For large J/t we find low-lying
quasiparticle-like bands which are well separated from an incoherent background
by a gap of order J. However, for small J/t this gap vanishes and the spectrum
becomes broad over an energy range of several t. The results are compared with
SCBA calculations and numerical data.Comment: 4 pages, 6 figs, to be publish in PR
Experimental Evidence for Resonant-Tunneling in a Luttinger-Liquid
We have measured the low temperature conductance of a one-dimensional island
embedded in a single mode quantum wire. The quantum wire is fabricated using
the cleaved edge overgrowth technique and the tunneling is through a single
state of the island. Our results show that while the resonance line shape fits
the derivative of the Fermi function the intrinsic line width decreases in a
power law fashion as the temperature is reduced. This behavior agrees
quantitatively with Furusaki's model for resonant tunneling in a
Luttinger-liquid.Comment: 3 pages, 5 figures, corrected typo
Quasi-Andreev reflection in inhomogeneous Luttinger liquids
Reflection of charge excitations at the step in the interaction strength in a
Luttinger liquid can be of the Andreev type, even if the interactions are
purely repulsive. The region with stronger repulsion plays the role of a normal
metal in a normal-metal /superconductor junction, whereas the region with
weaker repulsion plays the role of a superconductor. It is shown that this
quasi-Andreev reflection leads to a number of proximity-like effects, including
the local enhancement (suppression) of superconducting fluctuations on the
quasi-normal (quasi-superconducting) side of the step, significant modification
of the local density of states, as well as others. The observable consequences
of these proximity effects are analyzed for the case of single- and
two-particle tunneling from a normal-metal or superconducting tip into an
inhomogeneous Luttinger-liquid wire.Comment: 5 pages, 2 figures (eps
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