Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Anisotropy of incommensurate spin and charge fluctuations in detwinned
  YBa$_2$Cu$_3$O$_{6+\delta}$   Motivated by a recent neutron scattering experiment on detwinned
YBa$_2$Cu$_3$O$_{6+\delta}$ superconductor, we examine the frequency and doping
dependence of the anisotropy in the spin and charge fluctuation arising from
the coupling between the plane and the chain. Starting from the two-dimensional
$t$-$t^{'}$-$J$ model and using the random-phase approximation (RPA), we find a
pronounced anisotropy of the incommensurate (IC) peaks in the spin channel,
namely the peak intensity at the $(\pi\pm\delta,\pi)$ direction is stronger
than that at the $(\pi,\pi\pm\delta)$ direction in a wide frequency range from
$\omega=0.2J$ to the resonance frequency $\omega_r=0.35J$. Above the resonance
frequency, the IC peaks reemerge. Their intensities shift to the diagonal
direction and no anisotropy exists along the two diagonal directions. We find
that this anisotropy is robust with respect to the possible variation of the
RPA correction factor and to the dopings. The charge fluctuation is also found
to be incommensurate for all energies considered and peak at $(0,\delta)$ and
$(\delta,0)$. An anisotropy in its IC peak intensity along the $k_x$ and the
$k_y$ direction exists, but in sharp contrast to the spin channel, the maximum
intensity of the IC peak is along the $k_y$ direction. Moreover, the IC peak in
the charge channel exhibits an upward dispersion, in contrast to the downward
dispersion below the spin resonance frequency for the spin IC peak. We explain
these features based on the effect of the plane-chain coupling on the topology
of the Fermi surface.

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The categories of this paper are: acc-phys
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The categories of this paper are: mtrl-th
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The categories of this paper are: q-alg
6
The categories of this paper are: astro-ph
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The categories of this paper are: econ
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The categories of this paper are: math-ph
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The categories of this paper are: cmp-lg
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The categories of this paper are: nlin
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The categories of this paper are: nucl-th
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The categories of this paper are: hep-ph
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The categories of this paper are: bayes-an
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The categories of this paper are: physics
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The categories of this paper are: comp-gas
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The categories of this paper are: plasm-ph
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The categories of this paper are: hep-th
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The categories of this paper are: atom-ph