2,568 research outputs found
Disorder Screening in Strongly Correlated Systems
Electron-electron interactions generally reduce the low temperature
resistivity due to the screening of the impurity potential by the electron gas.
In the weak-coupling limit, the magnitude of this screening effect is
determined by the thermodynamic compressibility which is proportional to the
inverse screening length. We show that when strong correlations are present,
although the compressibility is reduced, the screening effect is nevertheless
strongly enhanced. This phenomenon is traced to the same non-perturbative
Kondo-like processes that lead to strong mass enhancements, but which are
absent in weak coupling approaches. We predict metallicity to be strongly
stabilized in an intermediate regime where the interactions and the disorder
are of comparable magnitude.Comment: 4+epsilon pages, 3 figure
Mathematical wind profiles
Augmented Fourier polynomials for mathematical representation of vertical profiles for horizontal wind velocitie
Critical behavior at Mott-Anderson transition: a TMT-DMFT perspective
We present a detailed analysis of the critical behavior close to the
Mott-Anderson transition. Our findings are based on a combination of numerical
and analytical results obtained within the framework of Typical-Medium Theory
(TMT-DMFT) - the simplest extension of dynamical mean field theory (DMFT)
capable of incorporating Anderson localization effects. By making use of
previous scaling studies of Anderson impurity models close to the
metal-insulator transition, we solve this problem analytically and reveal the
dependence of the critical behavior on the particle-hole symmetry. Our main
result is that, for sufficiently strong disorder, the Mott-Anderson transition
is characterized by a precisely defined two-fluid behavior, in which only a
fraction of the electrons undergo a "site selective" Mott localization; the
rest become Anderson-localized quasiparticles.Comment: 4+ pages, 4 figures, v2: minor changes, accepted for publication in
Phys. Rev. Let
Cauchy-perturbative matching and outer boundary conditions: computational studies
We present results from a new technique which allows extraction of
gravitational radiation information from a generic three-dimensional numerical
relativity code and provides stable outer boundary conditions. In our approach
we match the solution of a Cauchy evolution of the nonlinear Einstein field
equations to a set of one-dimensional linear equations obtained through
perturbation techniques over a curved background. We discuss the validity of
this approach in the case of linear and mildly nonlinear gravitational waves
and show how a numerical module developed for this purpose is able to provide
an accurate and numerically convergent description of the gravitational wave
propagation and a stable numerical evolution.Comment: 20 pages, RevTe
Weak-localization and rectification current in non-diffusive quantum wires
We show that electron transport in disordered quantum wires can be described
by a modified Cooperon equation, which coincides in form with the Dirac
equation for the massive fermions in a 1+1 dimensional system. In this new
formalism, we calculate the DC electric current induced by electromagnetic
fields in quasi-one-dimensional rings. This current changes sign, from
diamagnetic to paramagnetic, depending on the amplitude and frequency of the
time-dependent external electromagnetic field.Comment: changed title, added more detail, to appear in J. Phys.: Condens.
Matte
Cauchy-perturbative matching and outer boundary conditions I: Methods and tests
We present a new method of extracting gravitational radiation from
three-dimensional numerical relativity codes and providing outer boundary
conditions. Our approach matches the solution of a Cauchy evolution of
Einstein's equations to a set of one-dimensional linear wave equations on a
curved background. We illustrate the mathematical properties of our approach
and discuss a numerical module we have constructed for this purpose. This
module implements the perturbative matching approach in connection with a
generic three-dimensional numerical relativity simulation. Tests of its
accuracy and second-order convergence are presented with analytic linear wave
data.Comment: 13 pages, 6 figures, RevTe
31P nuclear magnetic resonance and X-ray diffraction study of Na-Sr-phosphate glass-ceramics
A set of Na-Sr-phosphate glass and glass-ceramic samples, with general formula
xSrO:(0.55-x)Na2O:0.45P2O5, were prepared and analysed by solid state 31P nuclear magnetic
resonance spectroscopy and X-ray powder diffraction. The results show the presence of Q1 and Q2
phosphate species in all samples. At low concentrations of Sr2+ (x £ 0.20) the strontium is
preferentially incorporated in Sr2+-Q1 crystalline phases, and only at higher Sr2+ concentrations are
crystalline phases present which Sr2+ is associated with Q2 phosphate units
The Evolution of Distorted Rotating Black Holes II: Dynamics and Analysis
We have developed a numerical code to study the evolution of distorted,
rotating black holes. This code is used to evolve a new family of black hole
initial data sets corresponding to distorted ``Kerr'' holes with a wide range
of rotation parameters, and distorted Schwarzschild black holes with odd-parity
radiation. Rotating black holes with rotation parameters as high as
are evolved and analyzed in this paper. The evolutions are generally carried
out to about , where is the ADM mass. We have extracted both the
even- and odd-parity gravitational waveforms, and find the quasinormal modes of
the holes to be excited in all cases. We also track the apparent horizons of
the black holes, and find them to be a useful tool for interpreting the
numerical results. We are able to compute the masses of the black holes from
the measurements of their apparent horizons, as well as the total energy
radiated and find their sum to be in excellent agreement with the ADM mass.Comment: 26 pages, LaTeX with RevTeX 3.0 macros. 27 uuencoded gz-compressed
postscript figures. Also available at http://jean-luc.ncsa.uiuc.edu/Papers/
Submitted to Physical Review
Gapless superconductivity and the Fermi arc in the cuprates
We argue that the Fermi arc observed in angle resolved photoemission
measurements in underdoped cuprates can be understood as a consequence of
inelastic scattering in a d-wave superconductor. We analyze this phenomenon in
the context of strong coupling Eliashberg theory, deriving a `single lifetime'
model for describing the temperature evolution of the spectral gap as measured
by single particle probes such as photoemission and tunneling.Comment: 4 pages, 2 figures. Submitted to PR
Ground state of a partially melted Wigner molecule
We consider three spinless fermions free to move on 2d square lattice with
periodic boundary conditions and interacting via a U/r Coulomb repulsion. When
the Coulomb energy to kinetic energy ratio r_s is large, a rigid Wigner
molecule is formed. As r_s decreases, we show that melting proceeds via an
intermediate regime where a floppy two particle molecule coexists with a
partially delocalized particle. A simple ansatz is given to describe the ground
state of this mesoscopic solid-liquid regime.Comment: to appear in Europhysics Letter
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