65 research outputs found
Charge and current oscillations in Fractional quantum Hall systems with edges
Stationary solutions of the Chern-Simons effective field theory for the
fractional quantum Hall systems with edges are presented for Hall bar, disk and
annulus. In the infinitely long Hall bar geometry (non compact case), the
charge density is shown to be monotonic inside the sample. In sharp contrast,
spatial oscillatory modes of charge density are found for the two circular
geometries, which indicate that in systems with compact geometry, charge and
current exist also far from the edges.Comment: 16 pages, 6 figures Revte
Distribution of spectral weight in a system with disordered stripes
The ``band-structure'' of a disordered stripe array is computed and compared,
at a qualitative level, to angle resolved photoemission experiments on the
cuprate high temperature superconductors. The low-energy states are found to be
strongly localized transverse to the stripe direction, so the electron dynamics
is strictly one-dimensional (along the stripe). Despite this, aspects of the
two dimensional band-structure Fermi surface are still vividly apparent.Comment: 10 pages, 11 figure
From the Chern-Simons theory for the fractional quantum Hall effect to the Luttinger model of its edges
The chiral Luttinger model for the edges of the fractional quantum Hall
effect is obtained as the low energy limit of the Chern-Simons theory for the
two dimensional system. In particular we recover the Kac-Moody algebra for the
creation and annihilation operators of the edge density waves and the
bosonization formula for the electronic operator at the edge.Comment: 4 pages, LaTeX, 1 Postscript figure include
Interacting Electrons on a Fluctuating String
We consider the problem of interacting electrons constrained to move on a
fluctuating one-dimensional string. An effective low-energy theory for the
electrons is derived by integrating out the string degrees of freedom to lowest
order in the inverse of the string tension and mass density, which are assumed
to be large. We obtain expressions for the tunneling density of states, the
spectral function and the optical conductivity of the system. Possible
connections with the phenomenology of the cuprate high temperature
superconductors are discussed.Comment: 14 pages, 1 figur
Photoemission Spectroscopy and the Unusually Robust One Dimensional Physics of Lithium Purple Bronze
Temperature dependent photoemission spectroscopy in Li0.9Mo6O17 contributes
to evidence for one dimensional physics that is unusually robust. Three generic
characteristics of the Luttinger liquid are observed, power law behavior of the
k-integrated spectral function down to temperatures just above the
superconducting transition, k-resolved lineshapes that show holon and spinon
features, and quantum critical (QC) scaling in the lineshapes. Departures of
the lineshapes and the scaling from expectations in the Tomonaga Luttinger
model can be partially described by a phenomenological momentum broadening that
is presented and discussed. The possibility that some form of 1d physics
obtains even down to the superconducting transition temperature is assessed.Comment: submitted to JPCM, Special issue article "Physics in one dimension
Probing Spin-Charge Separation in Tunnel-Coupled Parallel Quantum Wires
Interactions in one-dimensional (1D) electron systems are expected to cause a
dynamical separation of electronic spin and charge degrees of freedom. A
promising system for experimental observation of this non-Fermi-liquid effect
consists of two quantum wires coupled via tunneling through an extended uniform
barrier. Here we consider the minimal model of an interacting 1D electron
system exhibiting spin-charge separation and calculate the differential
tunneling conductance as well as the density-density response function. Both
quantities exhibit distinct strong features arising from spin-charge
separation. Our analysis of these features within the minimal model neglects
interactions between electrons of opposite chirality and applies therefore
directly to chiral 1D electron systems realized, e.g., at the edge of integer
quantum-Hall systems. Physical insight gained from our results is useful for
interpreting current experiment in quantum wires as our main conclusions still
apply with nonchiral interactions present. In particular, we discuss the effect
of charging due to applied voltages, and the possibility to observe spin-charge
separation in a time-resolved experiment.Comment: 9 pages, 3 figures, expanded version with many detail
Using strain to uncover the interplay between two- and three-dimensional charge density waves in high-temperature superconducting YBa<sub>2</sub>Cu<sub>3</sub>O<sub>y</sub>
Uniaxial pressure provides an efficient approach to control charge density waves in YBa2Cu3Oy. It can enhance the correlation volume of ubiquitous short-range two-dimensional charge-density-wave correlations, and induces a long-range three-dimensional charge density wave, otherwise only accessible at large magnetic fields. Here, we use x-ray diffraction to study the strain dependence of these charge density waves and uncover direct evidence for a form of competition between them. We show that this interplay is qualitatively described by including strain effects in a nonlinear sigma model of competing superconducting and charge-density-wave orders. Our analysis suggests that strain stabilizes the 3D charge density wave in the regions between disorder-pinned domains of 2D charge density waves, and that the two orders compete at the boundaries of these domains. No signatures of discommensurations nor of pair density waves are observed. From a broader perspective, our results underscore the potential of strain tuning as a powerful tool for probing competing orders in quantum materials
On the Relationship Between the Critical Temperature and the London Penetration Depth in Layered Organic Superconductors
We present an analysis of previously published measurements of the London
penetration depth of layered organic superconductors. The predictions of the
BCS theory of superconductivity are shown to disagree with the measured zero
temperature, in plane, London penetration depth by up to two orders of
magnitude. We find that fluctuations in the phase of the superconducting order
parameter do not determine the superconducting critical temperature as the
critical temperature predicted for a Kosterlitz--Thouless transition is more
than an order of magnitude greater than is found experimentally for some
materials. This places constraints on theories of superconductivity in these
materials.Comment: 5 pages, 1 figur
Theory of the Quantum Hall Smectic Phase II: Microscopic Theory
We present a microscopic derivation of the hydrodynamic theory of the Quantum
Hall smectic or stripe phase of a two-dimensional electron gas in a large
magnetic field. The effective action of the low energy is derived here from a
microscopic picture by integrating out high energy excitations with a scale of
the order the cyclotron energy.The remaining low-energy theory can be expressed
in terms of two canonically conjugate sets of degrees of freedom: the
displacement field, that describes the fluctuations of the shapes of the
stripes, and the local charge fluctuations on each stripe.Comment: 20 pages, RevTex, 3 figures, second part of cond-mat/0105448 New and
improved Introduction. Final version as it will appear in Physical Review
Phase Separation Models for Cuprate Stripe Arrays
An electronic phase separation model provides a natural explanation for a
large variety of experimental results in the cuprates, including evidence for
both stripes and larger domains, and a termination of the phase separation in
the slightly overdoped regime, when the average hole density equals that on the
charged stripes. Several models are presented for charged stripes, showing how
density waves, superconductivity, and strong correlations compete with quantum
size effects (QSEs) in narrow stripes. The energy bands associated with the
charged stripes develop in the middle of the Mott gap, and the splitting of
these bands can be understood by considering the QSE on a single ladder.Comment: significant revisions: includes island phase, 16 eps figures, revte
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