1,332 research outputs found
Inelastic neutron scattering peak in Zn substituted YBa2Cu3O7
The effects of nonmagnetic impurities on the neutron scattering intensity are
studied for a model of the copper oxide layers in the normal state. The
contribution to the Q=(pi,pi) neutron scattering intensity from processes
involving the scattering of the spin fluctuations from an impurity with large
momentum transfers are calculated within the random phase approximation. It is
shown that this type of scatterings could lead to a peak in the neutron
scattering intensity in the normal state.Comment: 4 pages, 4 figure
Strength of the d_{x^2-y^2} pairing in the two-leg Hubbard ladder
In the ground state of the doped two-leg Hubbard ladder there are power-law
decaying d_{x^2-y^2}-type pairing correlations. It is important to know the
strength and the temperature scale of these correlations. For this purpose, we
have performed determinantal Quantum Monte Carlo (QMC) calculations of the
reducible particle-particle interaction in the Hubbard ladder. In this paper,
we report on these calculations and show that, at sufficiently low
temperatures, resonant particle-particle scattering takes place in the
d_{x^2-y^2} pairing channel for certain values of the model parameters. The QMC
data presented here indicate that the d_{x^2-y^2} pairing correlations are
strong in the Hubbard ladder.Comment: 5 pages, 5 figure
Determining the structure of the superconducting gap in Cu_{2}O_{3} 2-leg ladder materials
Superconductivity has been recently observed in
Sr_{0.4}Ca_{13.6}Cu_{24}O_{41.84} which contains quasi-one-dimensional
Cu_{2}O_{3} 2-leg ladders. If, as suggested by some theories, the
superconductivity arises from these 2-leg ladders, it will be important to
determine the structure of the superconducting gap. In particular, does the gap
in a 2-leg ladder change sign when one goes from the bonding to antibonding
fermi surface points? Here we carry out phenomenological calculations of
nuclear relaxation rates and inelastic neutron scattering intensity in order to
provide estimates of the experimental resolution that will be required to
determine the structure of the superconducting gap associated with an array of
weakly coupled 2-leg ladders.Comment: 12 pages including 7 eps figures, uses revtex with eps
Wavelets in Field Theory
We advocate the use of Daubechies wavelets as a basis for treating a variety
of problems in quantum field theory. This basis has both natural large volume
and short distance cutoffs, has natural partitions of unity, and the basis
functions are all related to the fixed point of a linear renormalization group
equation.Comment: 42 pages, 2 figures, corrected typo
d_{x^2-y^2} Symmetry and the Pairing Mechanism
An important question is if the gap in the high temperature cuprates has
d_{x^2-y^2} symmetry, what does that tell us about the underlying interaction
responsible for pairing. Here we explore this by determining how three
different types of electron-phonon interactions affect the d_{x^2-y^2} pairing
found within an RPA treatment of the 2D Hubbard model. These results imply that
interactions which become more positive as the momentum transfer increases
favor d_{x^2-y^2} pairing in a nearly half-filled band.Comment: 9 pages and 2 eps figs, uses revtex with epsf, in press, PR
Quantum Monte Carlo study of a nonmagnetic impurity in the two-dimensional Hubbard model
In order to investigate the effects of nonmagnetic impurities in strongly
correlated systems, Quantum Monte Carlo (QMC) simulations have been carried out
for the doped two-dimensional Hubbard model with one nonmagnetic impurity.
Using a bare impurity potential which is onsite and attractive, magnetic and
single-particle properties have been calculated. The QMC results show that
giant oscillations develop in the Knight shift response around the impurity
site due to the short-range antiferromagnetic correlations. These results are
useful for interpreting the NMR data on Li and Zn substituted layered cuprates.Comment: 10 pages, 7 figure
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