Instruct: Identify the main and secondary category of Arxiv papers based on the titles and abstracts
Query: Dynamical magnetic susceptibility in the lamellar cobaltate
  superconductor Na_xCoO_2$\cdot y$H_2O   We systematically analyze the influence of the superconducting gap symmetry
and the electronic structure on the dynamical spin susceptibility in
superconducting Na_xCoO_2$\cdot y$H_2O within a three different models: the
single a_{1g}-band model with nearest-neighbor hoppings, the realistic
three-band t_{2g}-model with, and without e'_g pockets present at the Fermi
surface. We show that the magnetic response in the normal state is dominated by
the incommensurate antiferromagnetic spin density wave fluctuations at large
momenta in agreement with experimental temperature dependence of the
spin-lattice relaxation rate. Also, we demonstrate that the presence or the
absence of the e'_g-pockets at the Fermi surface does not affect significantly
this conclusion. In the superconducting state our results for d_{x^2-y^2}- or
d_{xy}-wave symmetries of the superconducting order parameter are consistent
with experimental data and exclude nodeless $d_{x^2-y^2} + id_{xy}$-wave
symmetry. We further point out that the spin-resonance peak proposed earlier is
improbable for the realistic band structure of Na_xCoO_2$\cdot y$H_2O.
Moreover, even if present the resonance peak is confined to the
antiferromagnetic wave vector and disappears away from it.

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The categories of this paper are: stat
37
The categories of this paper are: supr-con
0
The categories of this paper are: hep-ph
18
The categories of this paper are: econ
24
The categories of this paper are: dg-ga
12
The categories of this paper are: nucl-th
25
The categories of this paper are: patt-sol
28
The categories of this paper are: alg-geom
19
The categories of this paper are: eess
2
The categories of this paper are: math
31
The categories of this paper are: ao-sci
30
The categories of this paper are: q-alg
35
The categories of this paper are: mtrl-th
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The categories of this paper are: nucl-ex
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The categories of this paper are: math-ph
8
The categories of this paper are: hep-ex