4,166 research outputs found
Checkerboard patterns in the t-J model
Using the density matrix renormalization group, we study the possibility of
real space checkerboard patterns arising as the ground states of the t-J model.
We find that checkerboards with a commensurate (pi,pi) background are not low
energy states and can only be stabilized with large external potentials.
However, we find that striped states with charge density waves along the
stripes can form approximate checkerboard patterns. These states can be
stabilized with a very weak external field aligning and pinning the CDWs on
different stripes.Comment: 4 pages, 5 figure
Ground State Phases of the Doped 4-Leg t-J Ladder
Using density matrix renormalization group techniques, we have studied the
ground state of the 4-leg t-J ladder doped near half-filling. Depending upon
J/t and the hole doping x, three types of ground state phases are found: (1) a
phase containing d_{x^2-y^2} pairs; (2) a striped CDW domain-wall phase, and
(3) a phase separated regime. A CDW domain-wall consists of fluctuating hole
pairs and this phase has significant d_{x^2-y^2} pair field correlations.Comment: 10 pages, with 6 Postscript figure
d_{x^2-y^2} Pair Domain Walls
Using the density matrix renormalization group, we study domain wall
structures in the t-J model at a hole doping of x=1/8. We find that the domain
walls are composed of d_{x^2-y^2} pairs and that the regions between the domain
walls have antiferromagnetic correlations that are pi phase shifted across a
domain wall. At x=1/8, the hole filling corresponds to one hole per two domain
wall unit cells. When the pairs in a domain wall are pinned by an external
field, the d_{x^2-y^2} pairing response is suppressed, but when the pinning is
weakened, d_{x^2-y^2} pair-field correlations can develop.Comment: 11 pages, with 3 Postscript figure
Stripes on a 6-Leg Hubbard Ladder
While DMRG calculations find stripes on doped n-leg t-J ladders, little is
known about the possible formation of stripes on n-leg Hubbard ladders. Here we
report results for a 7x6 Hubbard model with 4 holes. We find that a stripe
forms for values of U/t ranging from 6 to 20. For U/t ~ 3-4, the system
exhibits the domain wall feature of a stripe, but the hole density is very
broadened.Comment: 4 pages, 5 figure
Real time evolution using the density matrix renormalization group
We describe an extension to the density matrix renormalization group method
incorporating real time evolution into the algorithm. Its application to
transport problems in systems out of equilibrium and frequency dependent
correlation functions is discussed and illustrated in several examples. We
simulate a scattering process in a spin chain which generates a spatially
non-local entangled wavefunction.Comment: 4 pages, 4 eps figures, some minor corrections in text and Eq.(3
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